Fix interpolate warning in console

raise if strokes selected on more than 1 accessible layers
exit code refacto

LICENSE

@@ -0,0 +1,674 @@
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+                       Version 3, 29 June 2007
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+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.

__init__.py

@@ -1,8 +1,8 @@
 bl_info = {
-    "name": "gp interpolate",
+    "name": "GP Interpolate",
     "author": "Christophe Seux, Samuel Bernou",
-    "version": (0, 7, 4),
+    "version": (0, 9, 1),
-    "blender": (3, 6, 0),
+    "blender": (4, 0, 2),
     "location": "Sidebar > Gpencil Tab > Interpolate",
     "description": "Interpolate Grease pencil strokes over 3D",
     "warning": "",

constants.py

@@ -0,0 +1,4 @@
+
+from pathlib import Path
+
+RESOURCES_DIR = Path(__file__).parent /'resources'

interpolate_strokes/__init__.py

@@ -1,14 +1,18 @@
-from gp_interpolate.interpolate_strokes import (operators,
+from gp_interpolate.interpolate_strokes import (properties,
-                                                properties,
+                                                operators,
+                                                operators_triangle,
+                                                operators_velocity,
                                                 debug,
-                                                #interpolate_simple
+                                                bind_points,
                                                 )
 
 modules = (
     properties,
     operators,
-    debug
+    operators_triangle,
-    #interpolate_simple,
+    operators_velocity,
+    debug,
+    bind_points,
 )
 
 if "bpy" in locals():

interpolate_strokes/bind_points.py

@@ -0,0 +1,384 @@
+import bpy
+import numpy as np
+from time import perf_counter, time, sleep
+from mathutils import Vector, Matrix
+
+from .. import utils
+
+from mathutils.geometry import (barycentric_transform,
+                                intersect_point_tri,
+                                intersect_point_line,
+                                intersect_line_plane,
+                                tessellate_polygon)
+
+import math
+import gpu
+from bpy_extras import view3d_utils
+from gpu_extras.batch import batch_for_shader
+
+
+def raycast_objects(context, event, dg):
+    """
+    Execute ray cast
+    return object hit, hit world location, normal of hitted face and face index
+    """
+
+    region = context.region
+    rv3d = context.region_data
+    coord = event.mouse_region_x, event.mouse_region_y
+
+    view_vector = view3d_utils.region_2d_to_vector_3d(region, rv3d, coord)
+    ray_origin = view3d_utils.region_2d_to_origin_3d(region, rv3d, coord)
+    ray_target = ray_origin + view_vector
+
+    def visible_objects_and_duplis():# -> Generator[tuple, Any, None]:
+        """Loop over (object, matrix) pairs (mesh only)"""
+
+        # depsgraph = dg  ## TRY to used passed depsgraph
+        depsgraph = context.evaluated_depsgraph_get()
+        for dup in depsgraph.object_instances:
+            if dup.is_instance:  # Real dupli instance
+                obj = dup.instance_object
+                yield (obj, dup.matrix_world.copy())
+            else:  # Usual object
+                obj = dup.object
+                yield (obj, obj.matrix_world.copy())
+
+    def obj_ray_cast(obj, matrix):
+        """Wrapper for ray casting that moves the ray into object space"""
+
+        # get the ray relative to the object
+        matrix_inv = matrix.inverted()
+        ray_origin_obj = matrix_inv @ ray_origin
+        ray_target_obj = matrix_inv @ ray_target
+        ray_direction_obj = ray_target_obj - ray_origin_obj
+
+        # cast the ray
+        success, location, normal, face_index = obj.ray_cast(ray_origin_obj, ray_direction_obj)
+
+        if success:
+            return location, normal, face_index
+        else:
+            return None, None, None
+
+    # cast rays and find the closest object
+    best_length_squared = -1.0
+    best_obj = None
+    face_normal = None
+    hit_loc = None
+    obj_face_index = None
+    for obj, matrix in visible_objects_and_duplis():
+        if obj.type == 'MESH':
+            hit, normal, face_index = obj_ray_cast(obj, matrix)
+            if hit is not None:
+                hit_world = matrix @ hit
+                # scene.cursor.location = hit_world
+                length_squared = (hit_world - ray_origin).length_squared
+                if best_obj is None or length_squared < best_length_squared:
+                    # print('length_squared',length_squared)
+                    best_length_squared = length_squared
+                    best_obj = obj
+                    face_normal = normal
+                    hit_loc = hit_world
+                    obj_face_index = face_index
+
+    if best_obj is not None:
+        best_original = best_obj.original
+        return best_original, hit_loc, face_normal, obj_face_index
+    
+    return None, None, None, None
+
+
+# -----------------
+### Drawing
+# -----------------
+
+def circle_2d(coord, r, num_segments):
+    '''create circle, ref: http://slabode.exofire.net/circle_draw.shtml'''
+    cx, cy = coord
+    points = []
+    theta = 2 * 3.1415926 / num_segments
+    c = math.cos(theta) #precalculate the sine and cosine
+    s = math.sin(theta)
+    x = r # we start at angle = 0
+    y = 0
+    for i in range(num_segments):
+        #bgl.glVertex2f(x + cx, y + cy) # output vertex
+        points.append((x + cx, y + cy))
+        # apply the rotation matrix
+        t = x
+        x = c * x - s * y
+        y = s * t + c * y
+
+    return points
+
+def draw_callback_px(self, context):
+    if context.area != self.current_area:
+        return
+
+    # 50% alpha, 2 pixel width line
+    shader = gpu.shader.from_builtin('UNIFORM_COLOR')
+    gpu.state.blend_set('ALPHA')
+    gpu.state.line_width_set(2.0)
+
+    view_rot = context.region_data.view_rotation
+
+    if self.current_points:
+        for coord in self.current_points:
+            # circle3d = [(view_normal.to_track_quat('-Z', 'Z') @ cp) + coord for cp in self.circle_pts]
+            circle3d = [(view_rot @ cp) + coord for cp in self.mini_circle_pts]
+            circle3d.append(circle3d[0]) # Loop with last point
+            batch = batch_for_shader(shader, 'LINE_STRIP', {"pos": circle3d})
+            shader.bind()
+            shader.uniform_float("color", (0.8, 0.8, 0.0, 0.9))
+            batch.draw(shader)
+
+    # Draw clicked path
+    if not self.point_list:
+        return
+
+    positions = [pt['co'] for pt in self.point_list]
+
+    line_color = color = (0.9, 0.1, 0.2, 0.8)
+
+    ## Draw lines
+
+    if len(self.point_list) >= 3:
+        ## Duplicate first position at last to loop triangle
+        positions += [self.point_list[0]['co']]
+        line_color = (0.9, 0.1, 0.3, 1.0)
+
+    batch = batch_for_shader(shader, 'LINE_STRIP', {"pos": positions})
+    shader.bind()
+    shader.uniform_float("color", line_color)
+    batch.draw(shader)
+
+    # Draw circle on point aligned with view
+
+    # view_normal = context.region_data.view_matrix.inverted() @ Vector((0,0,1))
+    
+    for pt in self.point_list:
+        coord = pt['co']
+
+        # circle3d = [(view_normal.to_track_quat('-Z', 'Z') @ cp) + coord for cp in self.circle_pts]
+        circle3d = [(view_rot @ cp) + coord for cp in self.circle_pts]
+        circle3d.append(circle3d[0]) # Loop with last point
+        batch = batch_for_shader(shader, 'LINE_STRIP', {"pos": circle3d})
+        shader.bind()
+        shader.uniform_float("color", color)
+        batch.draw(shader)
+
+    # restore opengl defaults
+    gpu.state.line_width_set(1.0)
+    gpu.state.blend_set('NONE')
+
+    ## POST_PIXEL for text
+
+
+# -----------------
+### Operator
+# -----------------
+
+class GP_OT_bind_points(bpy.types.Operator):
+    bl_idname = "gp.bind_points"
+    bl_label = "Bind Points"
+    bl_description = 'Bind points to use as reference for interpolation'
+    bl_options = {'REGISTER', 'UNDO'}
+
+    @classmethod
+    def poll(cls, context):
+        return context.object and context.object.type == 'GPENCIL'
+
+    clear : bpy.props.BoolProperty(name='Clear', default=False, options={'SKIP_SAVE'})
+
+    def invoke(self, context, event):
+        # print('INVOKE')
+        self.debug = False
+        self.gp = context.object
+        self.settings = context.scene.gp_interpo_settings
+        self.point_list = []
+        self.current_points = []
+        wm = context.window_manager
+        if tri_dump := wm.get(f'tri_{self.gp.name}'):
+            if self.clear:
+                del wm[f'tri_{self.gp.name}']
+                return {'FINISHED'}
+
+            ## load from current frame
+            ## Dict to list -> cast to dict (get ID prop array)
+            self.point_list = [dict(tri_dump[str(i)]) for i in range(3)]
+            
+            ## Update world coordinate position at current frame
+            dg = bpy.context.evaluated_depsgraph_get()
+            for point in self.point_list:
+                ob = bpy.context.scene.objects.get(point['object'])
+                ob_eval = ob.evaluated_get(dg)
+                point['co'] = ob_eval.matrix_world @ ob_eval.data.vertices[point['index']].co
+        
+        if self.clear:
+            return {'FINISHED'}
+        
+        ## Prepare circle 3D coordinate (create in invoke)
+        self.circle_pts = [Vector((p[0], p[1], 0)) for p in circle_2d((0,0), 0.01, 12)]
+        self.mini_circle_pts = [Vector((p[0], p[1], 0)) for p in circle_2d((0,0), 0.005, 12)]
+
+        # self._timer = wm.event_timer_add(0.01, window=context.window)
+
+        # draw in view space with 'POST_VIEW' and 'PRE_VIEW'
+        self.current_area = context.area
+        args = (self, context)
+        self._handle = bpy.types.SpaceView3D.draw_handler_add(draw_callback_px, args, 'WINDOW', 'POST_VIEW')
+        context.area.header_text_set('Bind points | Enter: Valid | Backspace: remove last point | Esc / Right-Click: Cancel')
+        wm.modal_handler_add(self)
+        return {'RUNNING_MODAL'}
+
+    def exit_modal(self, context, status='INFO', text=None):
+        # print('Exit modal') # Dbg
+        ## Reset all drawing and report
+        bpy.types.SpaceView3D.draw_handler_remove(self._handle, 'WINDOW')
+        context.area.header_text_set(None)
+        context.area.tag_redraw()
+        if text:
+            self.report({status}, text)
+        else:
+            ## report standard info
+            self.report({'INFO'}, 'Done')
+
+    def get_closest_vert(self, object_hit, hit_location, _normal, face_index, dg):
+        
+        ob_eval = object_hit.evaluated_get(dg)
+        ## Get closest index on face and store
+        face = ob_eval.data.polygons[face_index]
+        
+        ## list(dict)
+        vertices_infos = [{
+                            'object': object_hit.name, # store object 'name'
+                            'index': vert_idx, # store vertex index
+                            'co': ob_eval.matrix_world @ ob_eval.data.vertices[vert_idx].co # store initial absolute coordinate
+                        }
+                            # vertex: ob_eval.data.vertices[vert_idx],
+                            for vert_idx in face.vertices]
+
+        ## Filter vertices by closest to hit_location
+        vertices_infos.sort(key=lambda x: (x['co'] - hit_location).length)
+        return vertices_infos[0]
+
+    def bind(self, context):
+        ## store points on scene/wm properties associated with GP object
+        context.window_manager[f'tri_{context.object.name}'] = {str(i) : d for i, d in enumerate(self.point_list)}
+        self.exit_modal(context, text='Bound!')
+
+    def modal(self, context, event):
+        context.area.tag_redraw()
+        if event.type in ('RIGHTMOUSE', 'ESC'):
+            context.area.header_text_set(f'Cancelling')
+            self.exit_modal(context, text='Cancelled')
+            return {'CANCELLED'}
+
+        if event.type in ('WHEELUPMOUSE', 'WHEELDOWNMOUSE', 'MIDDLEMOUSE'):
+            return {'PASS_THROUGH'}
+
+        ## disable hint if too intensive
+        if event.type in {'MOUSEMOVE'}:
+            ## permanent update on closest point position (too heavy to always compute ?)
+            dg = bpy.context.evaluated_depsgraph_get()
+            object_hit, hit_location, _normal, face_index = raycast_objects(context, event, bpy.context.evaluated_depsgraph_get())
+            if object_hit is None:
+                self.current_points = []
+            else:
+                pt = self.get_closest_vert(object_hit, hit_location, _normal, face_index, dg)
+                self.current_points = [pt['co']]
+            return {'PASS_THROUGH'}
+        
+        elif event.type in ('BACK_SPACE', 'DEL') and event.value == 'PRESS':
+            if self.point_list:
+                self.report({'INFO'}, 'Removed last point')
+                self.point_list.pop()
+
+
+        elif event.type in ('RET', 'SPACE') and event.value == 'PRESS':
+            ## Valid
+            if len(self.point_list) < 3:
+                self.exit_modal(context, status='ERROR', text='Not enough point selected, Cancelling')
+                return {'CANCELLED'}
+            else:
+                self.bind(context)
+                return {'FINISHED'}
+
+        elif event.type == 'LEFTMOUSE' and event.value == 'PRESS':
+            if len(self.point_list) >= 3:
+                # self.report({'WARNING'}, 'Already got 3 point')
+                self.bind(context)
+                return {'FINISHED'}
+            else:
+                ## Raycast surface and store point
+                dg = bpy.context.evaluated_depsgraph_get()
+
+                ## Basic rayvast (Do not consider object modifier or instance !) 
+                # mouse = event.mouse_region_x, event.mouse_region_y                
+                # view_mat = context.region_data.view_matrix.inverted()
+                # origin = view_mat.to_translation()
+                # depth3d = view_mat @ Vector((0, 0, -1))
+                # point = utils.region_to_location(mouse, depth3d)
+                # ray = (point - origin)
+                # hit, hit_location, normal, face_index, object_hit, matrix = bpy.context.scene.ray_cast(dg, origin, ray)
+
+                object_hit, hit_location, _normal, face_index = raycast_objects(context, event, dg)
+
+                ## Also use triangle coordinate in triangle ?! using raycast with tesselated triangle infos
+                # object_hit, hit_location, tri, tri_indices = ray_cast_point(point, origin, dg)                
+
+                if object_hit is None:
+                    self.report({'WARNING'}, 'Nothing hit, Retry on a surface')
+                else:
+                    # print('object_hit: ', object_hit, object_hit.is_evaluated)
+                    # print('hit_location: ', hit_location)
+                    # print('face_index: ', face_index)
+
+                    # context.scene.cursor.location = hit_location # Dbg
+
+                    ### // get vert on-place
+                    # ob_eval = object_hit.evaluated_get(dg)
+                    # print('ob_eval: ', ob_eval)
+                    # ## Get closest index on face and store
+                    # face = ob_eval.data.polygons[face_index]
+                    # ## Store list of tuples [(index, world_co, object_hit), ...]
+                    # vertices_infos = [(vert_idx,
+                    #                     ob_eval.matrix_world @ ob_eval.data.vertices[vert_idx].co,
+                    #                     object_hit) # Store original object.
+                    #                 for vert_idx in face.vertices]
+
+                    # ## Filter vedrtices by closest to hit_location
+                    # vertices_infos.sort(key=lambda x: (x['co'] - hit_location).length)
+                    
+                    # vert = vertices_infos[0]
+                    ### get vert on-place //
+
+                    vert = self.get_closest_vert(object_hit, hit_location, _normal, face_index, dg)
+
+                    # print('vert: ', vert)
+    
+                    # if self.point_list and [x for x in self.point_list if vert[0] == x[0] and vert[3] == x[3]]:
+                    if any(vert['index'] == x['index'] and vert['object'] == x['object'] for x in self.point_list):
+                        self.report({'WARNING'}, "Cannot use same point twice !")
+                    else:
+                        self.point_list += [vert]
+                        self.report({'INFO'}, f"Set point {len(self.point_list)}")
+
+        return {'RUNNING_MODAL'}
+
+    def execute(self, context):
+        return {"FINISHED"}
+
+classes = (
+    GP_OT_bind_points,
+)
+
+def register():
+    for c in classes:
+        bpy.utils.register_class(c)
+    
+        
+def unregister():
+    for c in reversed(classes):
+        bpy.utils.unregister_class(c)

interpolate_strokes/debug.py

@@ -174,13 +174,28 @@ class GP_OT_debug_geometry_interpolation_targets(bpy.types.Operator):
                             object_hit, hit_location, tri, tri_indices = ray_cast_point(square_co, origin, dg)
                         
                         is_hit = 'HIT' if object_hit else ''
-                        empty_at(name=f'{is_hit}search_{iteration}({ct})', pos=square_co, collection=debug_col, size=0.001, show_name=True) # type='SPHERE'
+                        ## Show all search square elements
+                        # empty_at(name=f'{is_hit}{i}search_{iteration}({ct})', pos=square_co, collection=debug_col, size=0.001, show_name=False) # type='SPHERE'
+                        
+                        ## Show only hit location (at hit location) 
+                        if is_hit:
+                            empty_at(name=f'{is_hit}{i}search_{iteration}({ct})', pos=hit_location, collection=debug_col, size=0.001, show_name=False) # type='SPHERE'
                         
                         if object_hit: # and object_hit in col.all_objects[:]:
                             context.scene.cursor.location = hit_location
-                            ## Get location coplanar with triangle
+                            ## On location coplanar with face triangle
-                            hit_location = intersect_line_plane(origin, point_co_world, tri[0], triangle_normal(*tri))
+                            # hit_location = intersect_line_plane(origin, point_co_world, hit_location, triangle_normal(*tri))
-                            empty_at(name=f'{object_hit.name}_{i}-{iteration}', pos=hit_location, collection=debug_col, type='SPHERE', size=0.001, show_name=True)
+
+                            ## On view plane 
+                            view_vec = context.scene.camera.matrix_world.to_quaternion() @ Vector((0,0,1))
+                            hit_location = intersect_line_plane(origin, point_co_world, hit_location, view_vec)
+
+                            ## An average of the two ?
+                            # hit_location_1 = intersect_line_plane(origin, point_co_world, hit_location, triangle_normal(*tri))
+                            # hit_location_2 = intersect_line_plane(origin, point_co_world, hit_location, view_vec)
+                            # hit_location = (hit_location_1 + hit_location_2) / 2
+
+                            empty_at(name=f'{object_hit.name}_{i}-{iteration}', pos=hit_location, collection=debug_col, type='SPHERE', size=0.001, show_name=False)
                             found = True
                             # print(f'{si}:{i} iteration {iteration}') # Dbg
                             break
@@ -196,7 +211,7 @@ class GP_OT_debug_geometry_interpolation_targets(bpy.types.Operator):
             else:
                 ## Hit at original position
                 print(object_hit.name)
-                empty_at(name=f'{object_hit.name}_{i}', pos=hit_location, collection=debug_col, type='SPHERE', size=0.001, show_name=True)
+                empty_at(name=f'{object_hit.name}_{i}', pos=hit_location, collection=debug_col, type='SPHERE', size=0.001, show_name=False)
 
         print('Done')
         return {'FINISHED'}

interpolate_strokes/operators.py

@@ -1,35 +1,58 @@
-import bpy
+from time import time
-import numpy as np
+import re
-from time import perf_counter, time, sleep
-from mathutils import Vector, Matrix
 
-from ..utils import (matrix_transform,
+import bpy
-                                  plane_on_bone,
+from mathutils import Vector
-                                  ray_cast_point,
-                                  obj_ray_cast,
-                                  intersect_with_tesselated_plane,
-                                  triangle_normal,
-                                  search_square,
-                                  get_gp_draw_plane,
-                                  create_plane,
-                                  following_keys,
-                                  index_list_from_bools,
-                                  attr_set)
 
 from mathutils.geometry import (barycentric_transform,
-                                intersect_point_tri,
+                                intersect_line_plane)
-                                intersect_point_line,
-                                intersect_line_plane,
-                                tessellate_polygon)
 
-## Converted to modal from "operator_single"
+from ..utils import (plane_on_bone,
+                    ray_cast_point,
+                    obj_ray_cast,
+                    triangle_normal,
+                    search_square,
+                    get_gp_draw_plane,
+                    create_plane,
+                    following_keys)
 
-class GP_OT_interpolate_stroke(bpy.types.Operator):
+
-    bl_idname = "gp.interpolate_stroke"
+class GP_OT_pick_collection(bpy.types.Operator):
-    bl_label = "Interpolate Stroke"
+    bl_idname = "gp.pick_collection"
-    bl_description = 'Interpolate Stroke'
+    bl_label = "Auto Pick Mesh Collection"
+    #bl_description = 'Pick Mesh Collection'
     bl_options = {'REGISTER', 'UNDO'}
 
+    @classmethod
+    def poll(cls, context):
+        return context.active_object and context.object.type == 'GPENCIL'
+
+    def execute(self, context):
+        parts = re.split(r'(-|_)', context.object.name)
+
+        for col in context.scene.collection.children_recursive:                    
+            for i in range(len(parts), -1, -1):
+                base = ''.join(parts[:i])
+                tgt_name = f'{base}_mesh'
+                if tgt_name == col.name:
+                    print(f'Automatic set "{tgt_name}"')
+                    context.scene.gp_interpo_settings.target_collection = col
+                    return {"FINISHED"}
+        
+        self.report({"WARNING"}, 'No Collection found')
+        return {"CANCELLED"}
+
+
+class GP_OT_interpolate_stroke_base(bpy.types.Operator):
+    bl_idname = "gp.interpolate_stroke_base"
+    bl_label = "Interpolate Stroke"
+    bl_description = 'Interpolate Stroke based on user bound triangle'
+    bl_options = {'REGISTER', 'UNDO'} 
+
+    interactive : bpy.props.BoolProperty(name='Interactive', default=False, options={'SKIP_SAVE'})
+    
+    next : bpy.props.BoolProperty(name='Next', default=True, options={'SKIP_SAVE'})
+
     @classmethod
     def poll(cls, context):
         if context.active_object and context.object.type == 'GPENCIL'\
@@ -40,56 +63,36 @@ class GP_OT_interpolate_stroke(bpy.types.Operator):
 
     @classmethod
     def description(cls, context, properties):
+        if properties.interactive:
+            return "Interactive interpolate mode\
+                    \nUse Left <- -> Right keys\
+                    \n+Ctrl to jump over key interpolated during modal"
         if properties.next:
-            return f"Interpolate Stroke Forward"
+            return "Interpolate Stroke Forward"
         else:
-            return f"Interpolate Stroke Backward"
+            return "Interpolate Stroke Backward"
 
-    next : bpy.props.BoolProperty(name='Next', default=True, options={'SKIP_SAVE'})
+    def apply_and_store(self, attrs):
-
+        '''individual item in attrs: (prop, attr, [new_val])'''
-    def apply_and_store(self):
+        for item in attrs:
-        # self.store = []
-        # item = (prop, attr, [new_val])
-        for item in self.store_list:
             prop, attr = item[:2]
-            self.store.append( (prop, attr, getattr(prop, attr)) )
+            self.stored_attrs.append( (prop, attr, getattr(prop, attr)) )
             if len(item) >= 3:
                 setattr(prop, attr, item[2])
     
     def restore(self):
-        for prop, attr, old_val in self.store:
+        for prop, attr, old_val in self.stored_attrs:
             setattr(prop, attr, old_val)
 
-    def invoke(self, context, event):
+    def exit(self, context, status='INFO', text=None, cancelled=False):
-        self.debug = False
-        self.status = 'START'
-        self.store_list = []
-        self.store = []
-        self.loop_count = 0
-        self.start = time()
-        self.scan_time = None
-        self.plane = None
-        self.toolcol = None
-        self.gp = context.object
-        self.settings = context.scene.gp_interpo_settings
-        self.frames_to_jump = None
-        self.cancelled = False
-
-        context.window_manager.modal_handler_add(self)
-        self._timer = context.window_manager.event_timer_add(0.01, window=context.window)
-        context.area.header_text_set('Starting interpolation | Esc: Cancel')
-        return {'RUNNING_MODAL'}
-
-    def exit_modal(self, context, status='INFO', text=None):
         context.area.header_text_set(None)
         wm = context.window_manager
-        wm.progress_end() # Pgs
+        if self.report_progress:
-        wm.event_timer_remove(self._timer)
+            wm.progress_end() # Pgs
+        if self.timer:
+            wm.event_timer_remove(self.timer)
         self.restore()
         if self.debug:
-            ## show as solid ?
-            # if self.plane is not None:
-            #     self.plane.display_type = 'SOLID'
             if self.scan_time is not None:
                 print(f"Paste'n'place time {time()-self.start - self.scan_time}s")
         else:
@@ -97,339 +100,416 @@ class GP_OT_interpolate_stroke(bpy.types.Operator):
                 ## Remove Plane and it's collection after use
                 if self.plane is not None:
                     bpy.data.objects.remove(self.plane)
-                if self.toolcol is not None:
+                if self.tool_col is not None:
-                    bpy.data.collections.remove(self.toolcol)
+                    bpy.data.collections.remove(self.tool_col)
 
-        cancel_state = '(Stopped!) ' if self.cancelled else ''
+        cancel_state = '(Stopped!) ' if cancelled else ''
         mess = f'{cancel_state}{self.loop_count} interpolated frame(s) ({time()-self.start:.3f}s)'
+        
         if text:
             print(mess)
             self.report({status}, text)
         else:
-            ## report standard info
+            self.report({'INFO'}, mess)
-            if self.loop_count > 1:
+        
-                self.report({'INFO'}, mess)
+        if status == 'INFO':
+            return {'FINISHED'}
+        return {'CANCELLED'}
+
+    # def get_stroke_to_interpolate(self, context):
+    #     ## Get strokes to interpolate
+    #     #tgt_strokes = [s for s in self.gp.data.layers.active.active_frame.strokes if s.select]
+    #     tgt_strokes = [s for l in self.layers for s in l.active_frame.strokes if s.select]
+
+    #     ## If nothing selected in sculpt/paint, Select all before triggering
+    #     if not tgt_strokes and context.mode in ('SCULPT_GPENCIL', 'PAINT_GPENCIL'):
+    #         for s in self.gp.data.layers.active.active_frame.strokes:
+    #             s.select = True
+    #         tgt_strokes = self.gp.data.layers.active.active_frame.strokes
+
+    #     if tgt_strokes:            
+    #         return tgt_strokes
+        
+    #     return self.exit(context, status='ERROR', text='No stroke selected!')
+            
+
+    ## Added to operators owns invoke with uper().invoke(context, event)
+    def invoke(self, context, event):
+        self.debug = False
+        self.stored_attrs = [] # context manager store/restore
+        self.loop_count = 0 # frames list iterator
+        self.start = time()
+        self.scan_time = None # to print time at exit in debug mode
+        self.plane = None # 3D Plane for bone interpolation
+        self.tool_col = None # collection containing 3D plane
+        self.gp = context.object
+        self.settings = context.scene.gp_interpo_settings
+        self.frames_to_jump = []
+        self.cancelled = False
+        self.timer = None
+        self.timer_event = 'TIMER'
+        self.report_progress = (self.settings.use_animation and not self.interactive)
+        self.interpolated_keys = {context.scene.frame_current}
+
+        ## Remove interpolation_plane collection ! (unseen, but can be hit)
+        if interp_plane := bpy.data.objects.get('interpolation_plane'):
+            bpy.data.objects.remove(interp_plane)
+        if interp_col := bpy.data.collections.get('interpolation_tool'):
+            bpy.data.collections.remove(interp_col)
+
+        if context.mode != 'EDIT_GPENCIL':
+            self.report({"ERROR"}, "Mode need to be Edit Grease Pencil")
+            return {"CANCELLED"}
+
+        ## Change active layer if strokes are selected only on this layer
+        self.layers = [l for l in self.gp.data.layers 
+                  if (not l.lock and l.active_frame and not l.hide)
+                  and next((s for s in l.active_frame.strokes if s.select), None)]
+        
+        self.strokes = [s for l in self.layers for s in l.active_frame.strokes if s.select]
+        if not self.strokes:
+            self.report({"ERROR"}, "No strokes selected")
+            return {"CANCELLED"}
+        
+        #if not self.layers:
+        #    return self.exit(context, status='ERROR', text='No stroke selected!')
+            
+        #elif len(layers) > 1:
+        #    return self.exit(context, status='ERROR', text='Strokes selected accross multiple layers!')
+        
+        ## Set active layer
+        #self.gp.data.layers.active = layers[0]
+        
+        if self.interactive:
+            self.frames_to_jump = following_keys(forward=True, animation=True)
+            self.frames_to_jump += following_keys(forward=False, animation=True)
+            self.frames_to_jump.append(context.scene.frame_current)
+            self.frames_to_jump.sort()
+            context.area.header_text_set('Frame interpolation < jump with left-right arrow keys > | Esc/Enter: Stop') # (+Ctrl to skip all already interpolated)
+        else:
+            ## Determine on what key/keys to jump
+            self.frames_to_jump = following_keys(forward=self.next, animation=self.settings.use_animation or self.interactive)
+            if not len(self.frames_to_jump):
+                return self.exit(context, status='WARNING', text='No keyframe available in this direction')
+            
+            # TODO: Expose timer (in preferences ?) to let user more time to see result between frames
+            self.timer = context.window_manager.event_timer_add(0.04, window=context.window)
+
+        if self.report_progress:
+            context.window_manager.progress_begin(self.frames_to_jump[0], self.frames_to_jump[-1]) # Pgs
+
 
     def modal(self, context, event):
+        scn = context.scene
 
-        if event.type in {'RIGHTMOUSE', 'ESC'}:
+        if event.type in {'RIGHTMOUSE', 'ESC', 'RET'}:
-            print('Cancelling')
+            return self.exit(context, status='WARNING', text='Cancelling', cancelled=True)
-            self.status = 'CANCELLED'
-            self.cancelled = True
-            context.area.header_text_set(f'Cancelling')
-            self.exit_modal(context)
-            return {'CANCELLED'}
 
-        if self.frames_to_jump:
+        if self.interactive:
+            frame = None
+            current_frame = context.scene.frame_current
+            self.loop_count = 0 # Reset to keep inifinite loop
+            if event.type == 'LEFT_ARROW' and event.value == 'PRESS':
+                if event.ctrl:
+                    frame = next((f for f in self.frames_to_jump[::-1] if f < current_frame and f not in self.interpolated_keys), None)
+                else:
+                    frame = next((f for f in self.frames_to_jump[::-1] if f < current_frame), None)
+            if event.type == 'RIGHT_ARROW' and event.value == 'PRESS':
+                if event.ctrl:
+                    frame = next((f for f in self.frames_to_jump if f > current_frame and f not in self.interpolated_keys), None)
+                else:
+                    frame = next((f for f in self.frames_to_jump if f > current_frame), None)
+
+            if (event.type in ('LEFT_ARROW', 'RIGHT_ARROW') and event.value == 'PRESS') and frame is None:
+                self.report({'WARNING'}, 'No frame to jump to in this direction!')
+
+        else:
             frame_num = len(self.frames_to_jump)
             percentage = (self.loop_count) / (frame_num) * 100
             context.area.header_text_set(f'Interpolation {percentage:.0f}% {self.loop_count + 1}/{frame_num} | Esc: Cancel')
-            # (frame: {self.frames_to_jump[self.loop_count]})
 
-        if self.status == 'START':
+        ## -- Enter if LOOPTIMER or INTERACTIVE left-right shortcut
-            scn = bpy.context.scene
+        if event.type == self.timer_event or (self.interactive and frame is not None):
-            ## Determine on what key/keys to jump
+            if not self.interactive:
-            self.frames_to_jump = following_keys(forward=self.next, all_keys=self.settings.use_animation)
+                frame = self.frames_to_jump[self.loop_count]
-            if not len(self.frames_to_jump):
+            scn.frame_set(frame)
-                self.exit_modal(context, status='WARNING', text='No keyframe available in this direction')
+            if frame in self.interpolated_keys:
-                return {'CANCELLED'}
+                 self.report({'INFO'}, f'SKIP {frame} (already interpolated)')
-            # print('self.frames_to_jump: ', self.frames_to_jump)
+                 return {'RUNNING_MODAL'}
+            print(f'-> {frame}')
+            if self.report_progress:
+                context.window_manager.progress_update(frame) # Pgs
 
-            self.gp = context.object
+            ## Interpolate function
-
+            self.interpolate_frame(context)
-            # matrix = np.array(self.gp.matrix_world, dtype='float64')
-            # origin = np.array(scn.camera.matrix_world.to_translation(), 'float64')
-            matrix = self.gp.matrix_world
-            origin = scn.camera.matrix_world.to_translation()
-            
-            col = self.settings.target_collection
-            if not col:
-                col = scn.collection
-
-            # print('----')
-            if not self.gp.data.layers.active:
-                self.exit_modal(context, status='ERROR', text='No active layer')
-                return {'CANCELLED'}
-            if not self.gp.data.layers.active.active_frame:
-                self.exit_modal(context, status='ERROR', text='No active frame')
-                return {'CANCELLED'}
-
-            tgt_strokes = [s for s in self.gp.data.layers.active.active_frame.strokes if s.select]
-            
-            ## If nothing selected in sculpt/paint, Select all before triggering
-            if not tgt_strokes and context.mode in ('SCULPT_GPENCIL', 'PAINT_GPENCIL'):
-                for s in self.gp.data.layers.active.active_frame.strokes:
-                    s.select = True
-                tgt_strokes = self.gp.data.layers.active.active_frame.strokes
-
-            if not tgt_strokes:            
-                self.exit_modal(context, status='ERROR', text='No stroke selected !')
-                return {'CANCELLED'}
-
-            included_cols = [c.name for c in self.gp.users_collection]
-            target_obj = None
-            
-            if self.settings.method == 'BONE':
-                if not self.settings.target_rig or not self.settings.target_bone:
-                    self.exit_modal(context, status='ERROR', text='No Bone selected')
-                    return {'CANCELLED'}
-
-                included_cols.append('interpolation_tool')
-
-                ## ensure collection and plane exists
-                # get/create collection
-                self.toolcol = bpy.data.collections.get('interpolation_tool')
-                if not self.toolcol:
-                    self.toolcol = bpy.data.collections.new('interpolation_tool')
-
-                if self.toolcol.name not in bpy.context.scene.collection.children:
-                    bpy.context.scene.collection.children.link(self.toolcol)
-                    self.toolcol.hide_viewport = True # needed ?
-                
-                # get/create meshplane
-                self.plane = bpy.data.objects.get('interpolation_plane')
-                if not self.plane:
-                    self.plane = create_plane(name='interpolation_plane')
-                    self.plane.select_set(False)
-
-                if self.plane.name not in self.toolcol.objects:
-                    self.toolcol.objects.link(self.plane)
-                target_obj = self.plane
-
-            elif self.settings.method == 'GEOMETRY':
-                ## Remove interpolation_plane collection ! (unseen, but can be hit)
-                if interp_plane := bpy.data.objects.get('interpolation_plane'):
-                    bpy.data.objects.remove(interp_plane)
-                if interp_col := bpy.data.collections.get('interpolation_tool'):
-                    bpy.data.collections.remove(interp_col)
-
-                if col != context.scene.collection:
-                    included_cols.append(col.name)
-                ## Maybe include a plane just behind geo ? probably bad idea
-            
-            elif self.settings.method == 'OBJECT':
-                if not self.settings.target_object:
-                    self.exit_modal(context, status='ERROR', text='No Object selected')
-                    return {'CANCELLED'}
-                col = scn.collection # Reset collection filter
-                target_obj = self.settings.target_object
-                if target_obj.library:
-                    ## Look if an override exists in scene to use instead of default object
-                    if (override := next((o for o in scn.objects if o.name == target_obj.name and o.override_library), None)):
-                        target_obj = override
-
-            ## Prepare context manager
-            self.store_list = [
-                # (context.view_layer.objects, 'active', self.gp),
-                (context.tool_settings, 'use_keyframe_insert_auto', True),
-                # (bpy.context.scene.render, 'simplify_subdivision', 0),
-                ]
-            
-            # TODO: collection filter for GEOMETRY mode optimization
-
-            ## Hide optimizations (safe for Bone Mode only, if no error)
-            # if self.settings.method == 'BONE':
-            #     ## TEST: Add collections containing rig (cannot be excluded)
-            #     # rig_parent_cols = [c.name for c in scn.collection.children_recursive if self.settings.target_rig.name in c.all_objects]
-            #     # included_cols += rig_parent_cols
-            #     for vlc in context.view_layer.layer_collection.children:
-            #         self.store_list.append(
-            #             # (vlc, 'exclude', vlc.name not in included_cols), # If excluded rig does not update !
-            #             (vlc, 'hide_viewport', vlc.name not in included_cols), # viewport viz
-            #         )
-            
-            # print(f'Preparation {time()-start:.4f}s')
-            ## Set everything in SETUP list
-            self.apply_and_store()
-
-            if self.settings.method == 'BONE':
-                ## replace plane
-                _bone_plane = plane_on_bone(self.settings.target_rig.pose.bones.get(self.settings.target_bone),
-                                            arm=self.settings.target_rig,
-                                            set_rotation=self.settings.use_bone_rotation,
-                                            mesh=True)
-
-                ## Set collection visibility
-                intercol = bpy.data.collections.get('interpolation_tool')
-                vl_col = bpy.context.view_layer.layer_collection.children.get(intercol.name)
-                intercol.hide_viewport = vl_col.exclude = vl_col.hide_viewport = False
-
-                # Override collection
-                col = intercol
-            
-            dg = bpy.context.evaluated_depsgraph_get()
-            self.strokes_data = []
-
-            for si, stroke in enumerate(tgt_strokes):
-                nb_points = len(stroke.points)
-
-                local_co = np.empty(nb_points * 3, dtype='float64')
-                stroke.points.foreach_get('co', local_co)
-                # local_co_3d = local_co.reshape((nb_points, 3))
-                world_co_3d = matrix_transform(local_co.reshape((nb_points, 3)), matrix)
-
-                stroke_data = []
-                for i, point in enumerate(stroke.points):
-                    point_co_world = world_co_3d[i]
-                    if target_obj:
-                        object_hit, hit_location, tri, tri_indices = obj_ray_cast(target_obj, Vector(point_co_world), origin, dg)
-                    else:
-                        # scene raycast
-                        object_hit, hit_location, tri, tri_indices = ray_cast_point(point_co_world, origin, dg)
-
-                    ## Increasing search range
-                    if not object_hit: # or object_hit not in col.all_objects[:]:
-                        found = False
-                        for iteration in range(1, 6):
-                            for square_co in search_square(point_co_world, factor=self.settings.search_range * iteration):
-
-                                if target_obj:
-                                    object_hit, hit_location, tri, tri_indices = obj_ray_cast(target_obj, Vector(square_co), origin, dg)
-                                else:
-                                    # scene raycast
-                                    object_hit, hit_location, tri, tri_indices = ray_cast_point(square_co, origin, dg)
-
-                                if object_hit:
-                                    ## Get location coplanar with triangle
-                                    hit_location = intersect_line_plane(origin, point_co_world, tri[0], triangle_normal(*tri))
-                                    found = True
-                                    # print(f'{si}:{i} iteration {iteration}') # Dbg
-                                    break
-
-                            if found:
-                                break
-
-                        if not found:
-                            ## /!\ ERROR ! No surface found!
-                            # For debugging, select only problematic stroke (and point)
-                            for sid, s in enumerate(tgt_strokes):
-                                s.select = sid == si
-                                for ip, p in enumerate(stroke.points):
-                                    p.select = ip == i
-                            self.exit_modal(context, status='ERROR', text=f'Stroke {si} point {i} could not find underlying geometry')
-                            return {'CANCELLED'}
-                    
-                    stroke_data.append((stroke, point_co_world, object_hit, hit_location, tri, tri_indices))
-
-                self.strokes_data.append(stroke_data)
-
-            if self.debug:
-                self.scan_time = time()-self.start
-                print(f'Scan time {self.scan_time:.4f}s')
-            
-            # Copy stroke selection
-            bpy.ops.gpencil.copy()
-
-            # Jump frame and paste
-            bpy.context.window_manager.progress_begin(self.frames_to_jump[0], self.frames_to_jump[-1]) # Pgs
-            self.status = 'LOOP'
-
-
-        ## -- LOOPTIMER 
-        if event.type == 'TIMER':
-            
-            if self.status == 'LOOP':
-                f = self.frames_to_jump[self.loop_count]
-                bpy.context.window_manager.progress_update(f) # Pgs
-                scn = bpy.context.scene
-                scn.frame_set(f)
-                origin = scn.camera.matrix_world.to_translation()
-                # origin = np.array(scn.camera.matrix_world.to_translation(), 'float64')
-                plan_co, plane_no = get_gp_draw_plane(self.gp)
-                bpy.ops.gpencil.paste()
-
-                if self.settings.method == 'BONE':
-                    bone_plane = plane_on_bone(self.settings.target_rig.pose.bones.get(self.settings.target_bone),
-                                                arm=self.settings.target_rig,
-                                                set_rotation=self.settings.use_bone_rotation,
-                                                mesh=True)
-                    
-                dg = bpy.context.evaluated_depsgraph_get()
-                matrix_inv = np.array(self.gp.matrix_world.inverted(), dtype='float64')#.inverted()
-                new_strokes = self.gp.data.layers.active.active_frame.strokes[-len(self.strokes_data):]
-
-                # for new_stroke, stroke_data in zip(new_strokes, self.strokes_data):
-                for new_stroke, stroke_data in zip(reversed(new_strokes), reversed(self.strokes_data)):
-                    world_co_3d = []
-                    for stroke, point_co, object_hit, hit_location, tri_a, tri_indices in stroke_data:
-                        eval_ob = object_hit.evaluated_get(dg)
-                        tri_b = [eval_ob.data.vertices[i].co for i in tri_indices]
-                        tri_b = matrix_transform(tri_b, eval_ob.matrix_world)
-
-                        new_loc = barycentric_transform(hit_location, *tri_a, *tri_b)
-                        # try:
-                        #     new_loc = barycentric_transform(hit_location, *tri_a, *tri_b)
-                        # except Exception as e:
-                        #     print(f'\nCould not apply barycentric tranform {eval_ob.name}')
-                        #     print(e)
-                        #     # bpy.context.scene.cursor.location = hit_location
-                        #     self.report({'ERROR'}, f'Stroke {si} point {i} could not find underlying geometry')
-                        #     return {'CANCELLED'}
-                            
-                        world_co_3d.append(new_loc)
-
-                    ## Test with point in 3D space (Debug)
-                    # nb_points = len(new_stroke.points)
-                    # new_stroke.points.foreach_set('co', np.array(world_co_3d).reshape(nb_points*3))
-                    # new_stroke.points.update()
-
-                    ## Reproject on plane
-                    new_world_co_3d = [intersect_line_plane(origin, p, plan_co, plane_no) for p in world_co_3d]        
-                    new_local_co_3d = matrix_transform(new_world_co_3d, matrix_inv)
-
-                    nb_points = len(new_stroke.points)
-                    new_stroke.points.foreach_set('co', new_local_co_3d.reshape(nb_points*3))
-                    new_stroke.points.update()
-
-                    
-                    ## Occlusion management
-                    if self.settings.method == 'GEOMETRY' and self.settings.remove_occluded:
-                        viz_list = [True]*len(world_co_3d)
-                        for i, nco in enumerate(world_co_3d):
-                            vec_direction = nco - origin
-                            ## Reduced distance slightly to avoid occlusion on same source...
-                            dist = vec_direction.length - 0.001
-                            n_hit, _hit_location, _normal, _n_face_index, n_object_hit, _matrix = scn.ray_cast(dg, origin, vec_direction, distance=dist)
-                            # if there is a hit, it's occluded
-                            if n_hit:
-                                viz_list[i] = False
-
-                        if all(viz_list):
-                            # All visible, do nothing (just keep previous stroke)
-                            continue
-
-                        if any(viz_list):
-                            # Create sub-strokes according to indices in original stroke
-                            for sublist in index_list_from_bools(viz_list):
-                                ## Clear if only one isolated point ?
-                                if len(sublist) == 1:
-                                    continue
-
-                                ns = self.gp.data.layers.active.active_frame.strokes.new()
-                                for elem in ('hardness', 'material_index', 'line_width'):
-                                    setattr(ns, elem, getattr(new_stroke, elem))
-
-                                ns.points.add(len(sublist))
-                                for i, point_index in enumerate(sublist):
-                                    for elem in ('uv_factor', 'uv_fill', 'uv_rotation', 'pressure', 'co', 'strength', 'vertex_color'):
-                                        setattr(ns.points[i], elem, getattr(new_stroke.points[point_index], elem))
-
-                        ## Delete original stroke
-                        self.gp.data.layers.active.active_frame.strokes.remove(new_stroke)
             
+            if self.interactive:
+                self.interpolated_keys.add(frame)
+            else:
                 self.loop_count += 1
                 if self.loop_count >= len(self.frames_to_jump):
-                    self.exit_modal(context)
+                    return self.exit(context)
-                    return {'FINISHED'}
 
-                bpy.ops.wm.redraw_timer(type='DRAW_WIN_SWAP', iterations=1)
+                # bpy.ops.wm.redraw_timer(type='DRAW_WIN_SWAP', iterations=1)
-                # context.area.tag_redraw()
 
         return {'RUNNING_MODAL'}
 
+    def interpolate_frame(self, context):
+        raise Exception('Not Implemented')
+
+
+## Converted to modal from "operator_single"
+
+class GP_OT_interpolate_stroke(GP_OT_interpolate_stroke_base):
+    bl_idname = "gp.interpolate_stroke"
+    bl_label = "Interpolate Stroke"
+    bl_description = 'Interpolate Stroke'
+    bl_options = {'REGISTER', 'UNDO'} 
+
+    def iterative_search(self, context, obj, coord, origin, dg):
+        '''Search geometry for outside point (where raycast did not hit any geometry)
+        
+        return :
+            object_hit, hit_location, tri, tri_indices.
+            None if nothing found
+        '''
+
+        for iteration in range(1, 10):
+            for square_co in search_square(coord, factor=self.settings.search_range * iteration):
+
+                if obj:
+                    object_hit, hit_location, tri, tri_indices = obj_ray_cast(obj, square_co, origin, dg)
+                else:
+                    object_hit, hit_location, tri, tri_indices = ray_cast_point(square_co, origin, dg)
+
+                if object_hit:
+                    ## On location coplanar with face triangle
+                    # hit_location = intersect_line_plane(origin, coord, hit_location, triangle_normal(*tri))
+
+                    ## On view plane 
+                    view_vec = context.scene.camera.matrix_world.to_quaternion() @ Vector((0,0,1))
+                    hit_location = intersect_line_plane(origin, coord, hit_location, view_vec)
+
+                    ## An average of the two ?
+                    # hit_location_1 = intersect_line_plane(origin, coord, hit_location, triangle_normal(*tri))
+                    # hit_location_2 = intersect_line_plane(origin, coord, hit_location, view_vec)
+                    # hit_location = (hit_location_1 + hit_location_2) / 2
+
+                    return object_hit, hit_location, tri, tri_indices 
+
+        return None, None, None, None
+
+    def invoke(self, context, event):
+        if state := super().invoke(context, event):
+            return state
+
+        scn = context.scene
+
+        origin = scn.camera.matrix_world.to_translation()
+        
+        strokes = [s for l in self.layers for s in l.active_frame.strokes if s.select]
+        if not strokes:
+            self.report({"ERROR"}, "No strokes selected")
+            return {"CANCELLED"}
+
+        col = self.settings.target_collection
+        if not col:
+            col = scn.collection
+
+        included_cols = [c.name for c in self.gp.users_collection]
+        target_obj = None
+        
+        ## Setup depending on method
+        if self.settings.method == 'BONE':
+            if not self.settings.target_rig or not self.settings.target_bone:
+                return self.exit(context, status='ERROR', text='No Bone selected')
+
+            included_cols.append('interpolation_tool')
+
+            ## Ensure collection and plane exists
+            # get/create collection
+            self.tool_col = bpy.data.collections.get('interpolation_tool')
+            if not self.tool_col:
+                self.tool_col = bpy.data.collections.new('interpolation_tool')
+
+            if self.tool_col.name not in bpy.context.scene.collection.children:
+                bpy.context.scene.collection.children.link(self.tool_col)
+                self.tool_col.hide_viewport = True # needed ?
+            
+            # get/create meshplane
+            self.plane = bpy.data.objects.get('interpolation_plane')
+            if not self.plane:
+                self.plane = create_plane(name='interpolation_plane')
+                self.plane.select_set(False)
+
+            if self.plane.name not in self.tool_col.objects:
+                self.tool_col.objects.link(self.plane)
+            target_obj = self.plane
+
+        elif self.settings.method == 'GEOMETRY':
+            if col != context.scene.collection:
+                included_cols.append(col.name)
+        
+        elif self.settings.method == 'OBJECT':
+            if not self.settings.target_object:
+                return self.exit(context, status='ERROR', text='No Object selected')
+                
+            col = scn.collection # Reset collection filter
+            target_obj = self.settings.target_object
+            if target_obj.library:
+                ## Look if an override exists in scene to use instead of default object
+                if (override := next((o for o in scn.objects if o.name == target_obj.name and o.override_library), None)):
+                    target_obj = override
+
+        ## Prepare context manager
+        attrs = [
+            # (context.view_layer.objects, 'active', self.gp),
+            (context.tool_settings, 'use_keyframe_insert_auto', True),
+            # (bpy.context.scene.render, 'simplify_subdivision', 0),
+            ]
+
+        ## Set everything in SETUP list
+        self.apply_and_store(attrs)
+
+        if self.settings.method == 'BONE':
+            ## replace plane
+            _bone_plane = plane_on_bone(self.settings.target_rig.pose.bones.get(self.settings.target_bone),
+                                        arm=self.settings.target_rig,
+                                        set_rotation=self.settings.use_bone_rotation,
+                                        mesh=True)
+
+            ## Set collection visibility
+            intercol = bpy.data.collections.get('interpolation_tool')
+            vl_col = bpy.context.view_layer.layer_collection.children.get(intercol.name)
+            intercol.hide_viewport = vl_col.exclude = vl_col.hide_viewport = False
+
+            ## Override collection
+            col = intercol
+        
+        dg = bpy.context.evaluated_depsgraph_get()
+        self.strokes_data = []
+
+        for stroke_index, stroke in enumerate(strokes):
+            stroke_data = []
+            for point_index, point in enumerate(stroke.points):
+                point_co_world = self.gp.matrix_world @ point.co
+
+                if target_obj:
+                    ## Object raycast
+                    object_hit, hit_location, tri, tri_indices = obj_ray_cast(target_obj, point_co_world, origin, dg)
+                else:
+                    ## Scene raycast
+                    object_hit, hit_location, tri, tri_indices = ray_cast_point(point_co_world, origin, dg)
+
+                ## Iterative increasing search range when no surface hit
+                if not object_hit:
+                    object_hit, hit_location, tri, tri_indices = self.iterative_search(context, target_obj, point_co_world, origin, dg)
+
+                    if not object_hit:
+                        ## /!\ ERROR ! No surface found!
+                        # For debugging, select only point.
+                        bpy.ops.gpencil.select_all(action='DESELECT')
+                        point.select = True
+                        return self.exit(context, status='ERROR', text=f'Stroke {stroke_index} point {point_index} could not find underlying geometry')
+                
+                stroke_data.append((stroke, point_co_world, object_hit, hit_location, tri, tri_indices))
+
+            self.strokes_data.append(stroke_data)
+
+        if self.debug:
+            self.scan_time = time()-self.start
+            print(f'Scan time {self.scan_time:.4f}s')
+        
+        # Copy stroke selection
+        bpy.ops.gpencil.select_linked() # Ensure whole stroke are selected before copy
+        bpy.ops.gpencil.copy()
+
+        context.window_manager.modal_handler_add(self)
+        return {'RUNNING_MODAL'}
+
+    def interpolate_frame(self, context):
+        scn = context.scene
+        origin = scn.camera.matrix_world.to_translation()
+        plane_co, plane_no = get_gp_draw_plane(self.gp)
+        bpy.ops.gpencil.select_all(action='DESELECT')
+        bpy.ops.gpencil.paste(type='LAYER')
+
+        if self.settings.method == 'BONE':
+            ## Set plane on the bone
+            plane_on_bone(self.settings.target_rig.pose.bones.get(self.settings.target_bone),
+                                        arm=self.settings.target_rig,
+                                        set_rotation=self.settings.use_bone_rotation,
+                                        mesh=True)
+
+        dg = bpy.context.evaluated_depsgraph_get()
+        
+        ## Get pasted stroke
+        #new_strokes = [s for s in self.gp.data.layers.active.active_frame.strokes if s.select]
+        new_strokes = [s for l in self.layers for s in l.active_frame.strokes if s.select]
+        ## Keep reference to all accessible other strokes (in all accessible layer)
+        other_strokes = [s for l in self.gp.data.layers if l.active_frame and not l.lock for s in l.active_frame.strokes if not s.select]
+        
+        smooth_level = self.settings.smooth_level
+
+        occluded_points = []
+        for new_stroke, stroke_data in zip(list(new_strokes), list(self.strokes_data)):
+            world_co_3d = []
+            for stroke, point_co, object_hit, hit_location, tri_a, tri_indices in stroke_data:
+                eval_ob = object_hit.evaluated_get(dg)
+                tri_b = [eval_ob.matrix_world @ eval_ob.data.vertices[i].co for i in tri_indices]
+
+                new_loc = barycentric_transform(hit_location, *tri_a, *tri_b) 
+                world_co_3d.append(new_loc)
+
+            # Smooth points
+            if smooth_level:
+                old_co_3d = [s[1] for s in stroke_data]
+                points_velocity = [b-a for a, b in zip(old_co_3d, world_co_3d)]
+
+                # Average of points
+                for i in range(smooth_level + 1):
+                    points_velocity = [
+                        (points_velocity[i] + points_velocity[i + 1]) / 2 if i == 0 else
+                        (points_velocity[i] + points_velocity[i - 1]) / 2 if i == len(points_velocity) - 1 else
+                        (points_velocity[i - 1] + points_velocity[i] + points_velocity[i + 1]) / 3
+                        for i in range(len(points_velocity))
+                    ]
+                
+                world_co_3d = [a+b for a, b in zip(old_co_3d, points_velocity)]
+
+            ## Reproject on plane
+            new_world_co_3d = [intersect_line_plane(origin, p, plane_co, plane_no) for p in world_co_3d]        
+            new_local_co_3d = [co for coord in new_world_co_3d for co in self.gp.matrix_world.inverted() @ coord]
+            new_stroke.points.foreach_set('co', new_local_co_3d)
+            new_stroke.points.update()
+
+            ## Occlusion management
+            if self.settings.method == 'GEOMETRY' and self.settings.remove_occluded:
+                for i, point in enumerate(new_stroke.points):
+                    point_co = world_co_3d[i]
+                    vec_direction = point_co - origin
+                    ## Raycast with slightly reduced distance (avoid occlusion on initial surface)
+                    n_hit, _, _, _, _, _ = scn.ray_cast(dg, origin, vec_direction, distance=vec_direction.length - 0.001)
+                    if n_hit:
+                        occluded_points.append(point)
+
+        if occluded_points:
+            ## Select only occluded point
+            bpy.ops.gpencil.select_all(action='DESELECT')
+            for point in occluded_points:
+                point.select = True
+            ## remove points
+            bpy.ops.gpencil.delete(type='POINTS')
+
+            ## restore selection (keep new strokes selected)
+            bpy.ops.gpencil.select_all(action='SELECT')
+            for stroke in other_strokes:
+                stroke.select = False
+
 
 classes = (
     GP_OT_interpolate_stroke,
+    GP_OT_pick_collection
 )
 
 def register():

interpolate_strokes/operators_single.py

@@ -59,7 +59,7 @@ class GP_OT_interpolate_stroke(bpy.types.Operator):
         # context.tool_settings.use_keyframe_insert_auto = True
 
         ## Determine on what key/keys to jump
-        frames_to_jump = following_keys(forward=self.next, all_keys=settings.use_animation)
+        frames_to_jump = following_keys(forward=self.next, animation=settings.use_animation)
         if not len(frames_to_jump):
             self.report({'WARNING'}, 'No keyframe available in this direction')
             return {'CANCELLED'}
@@ -78,7 +78,7 @@ class GP_OT_interpolate_stroke(bpy.types.Operator):
 
         # print('----')
 
-        tgt_strokes = [s for s in gp.data.layers.active.active_frame.strokes if s.select]
+        tgt_strokes = [s for l in self.layers for s in l.active_frame.strokes if s.select]
         
         ## If nothing selected in sculpt/paint, Select all before triggering
         if not tgt_strokes and context.mode in ('SCULPT_GPENCIL', 'PAINT_GPENCIL'):
@@ -247,7 +247,7 @@ class GP_OT_interpolate_stroke(bpy.types.Operator):
                 origin = scn.camera.matrix_world.to_translation()
                 # origin = np.array(scn.camera.matrix_world.to_translation(), 'float64')
                 plan_co, plane_no = get_gp_draw_plane(gp)
-                bpy.ops.gpencil.paste()
+                bpy.ops.gpencil.paste(type="LAYER")
 
                 if settings.method == 'BONE':
                     bone_plane = plane_on_bone(settings.target_rig.pose.bones.get(settings.target_bone),
@@ -257,10 +257,10 @@ class GP_OT_interpolate_stroke(bpy.types.Operator):
                     
                 dg = bpy.context.evaluated_depsgraph_get()
                 matrix_inv = np.array(gp.matrix_world.inverted(), dtype='float64')#.inverted()
-                new_strokes = gp.data.layers.active.active_frame.strokes[-len(strokes_data):]
+                new_strokes = [(l, s) for l in self.layers for s in l.active_frame.strokes if s.select]
 
                 # for new_stroke, stroke_data in zip(new_strokes, strokes_data):
-                for new_stroke, stroke_data in zip(reversed(new_strokes), reversed(strokes_data)):
+                for (layer, new_stroke), stroke_data in zip(reversed(new_strokes), reversed(strokes_data)):
                     world_co_3d = []
                     for stroke, point_co, object_hit, hit_location, tri_a, tri_indices in stroke_data:
                         eval_ob = object_hit.evaluated_get(dg)
@@ -316,7 +316,7 @@ class GP_OT_interpolate_stroke(bpy.types.Operator):
                                 if len(sublist) == 1:
                                     continue
 
-                                ns = gp.data.layers.active.active_frame.strokes.new()
+                                ns = layer.active_frame.strokes.new()
                                 for elem in ('hardness', 'material_index', 'line_width'):
                                     setattr(ns, elem, getattr(new_stroke, elem))
 
@@ -326,7 +326,7 @@ class GP_OT_interpolate_stroke(bpy.types.Operator):
                                         setattr(ns.points[i], elem, getattr(new_stroke.points[point_index], elem))
 
                         ## Delete original stroke
-                        gp.data.layers.active.active_frame.strokes.remove(new_stroke)
+                        layer.active_frame.strokes.remove(new_stroke)
 
             wm.progress_end() # Pgs
 

interpolate_strokes/operators_triangle.py

@@ -0,0 +1,127 @@
+import bpy
+from time import time
+
+from mathutils.geometry import (barycentric_transform,
+                                intersect_line_plane)
+
+from ..utils import (triangle_normal,
+                    get_gp_draw_plane)
+
+from .operators import GP_OT_interpolate_stroke_base
+
+
+class GP_OT_interpolate_stroke_tri(GP_OT_interpolate_stroke_base):
+    bl_idname = "gp.interpolate_stroke_tri"
+    bl_label = "Interpolate Stroke"
+    bl_description = 'Interpolate Stroke based on user bound triangle'
+    bl_options = {'REGISTER', 'UNDO'} 
+
+    def invoke(self, context, event):
+        if state := super().invoke(context, event):
+            return state
+
+        if not context.window_manager.get(f'tri_{self.gp.name}'):
+            return self.exit(context, status='ERROR', text='Need to bind coordinate first. Use "Bind Tri Point" button')
+
+        scn = bpy.context.scene
+
+        origin = scn.camera.matrix_world.to_translation()
+    
+        ## Prepare context manager
+        attrs = [
+            # (context.view_layer.objects, 'active', self.gp),
+            (context.tool_settings, 'use_keyframe_insert_auto', True),
+            # (bpy.context.scene.render, 'simplify_subdivision', 0),
+            ]
+        self.apply_and_store(attrs)
+        
+        point_dict = context.window_manager.get(f'tri_{self.gp.name}')
+        ## point_dict -> {'0': {'object': object_name_as_str, 'index': 450}, ...}
+        ## Get triangle dumped in context.window_manager
+        self.source_object_list = [bpy.context.scene.objects.get(point_dict[str(i)]['object']) for i in range(3)]
+        self.source_tri_indices = [point_dict[str(i)]['index'] for i in range(3)] # List of vertices index corresponding to tri coordinates
+        
+        dg = bpy.context.evaluated_depsgraph_get()
+        
+        ## Get tri at source frame
+        tri = []
+        for source_obj, idx in zip(self.source_object_list, self.source_tri_indices):
+            ob_eval = source_obj.evaluated_get(dg)
+            tri.append(ob_eval.matrix_world @ ob_eval.data.vertices[idx].co)
+
+        self.strokes_data = []
+
+        for stroke in self.strokes:
+            stroke_data = []
+            for point in stroke.points:
+                point_co_world = self.gp.matrix_world @ point.co
+
+                ## Set hit location at same coordinate as point
+                # hit_location = point_co_world
+                
+                ## Set hit location on tri plane
+                hit_location = intersect_line_plane(origin, point_co_world, tri[0], triangle_normal(*tri))
+
+                stroke_data.append((hit_location, tri))
+
+            self.strokes_data.append(stroke_data)
+
+        if self.debug:
+            self.scan_time = time()-self.start
+            print(f'Scan time {self.scan_time:.4f}s')
+
+        # Ensure whole stroke are selected before copy
+        bpy.ops.gpencil.select_linked()
+        # Copy stroke selection
+        bpy.ops.gpencil.copy()
+
+        # Jump frame and paste
+        # if self.report_progress:
+        #     context.window_manager.progress_begin(self.frames_to_jump[0], self.frames_to_jump[-1]) # Pgs
+        # context.area.header_text_set('Starting interpolation | Esc: Cancel')
+
+        context.window_manager.modal_handler_add(self)
+        return {'RUNNING_MODAL'}
+
+    def interpolate_frame(self, context):
+        scn = context.scene
+        origin = scn.camera.matrix_world.to_translation()
+        plane_co, plane_no = get_gp_draw_plane(self.gp)
+        bpy.ops.gpencil.paste(type='LAYER')
+
+        dg = bpy.context.evaluated_depsgraph_get()
+        
+        ## List of newly pasted strokes (using range)
+        new_strokes = [s for l in self.layers for s in l.active_frame.strokes if s.select]
+        #new_strokes = self.gp.data.layers.active.active_frame.strokes[-len(self.strokes_data):]
+
+        ## Get user triangle position at current frame
+        tri_b = []
+        for source_obj, idx in zip(self.source_object_list, self.source_tri_indices):
+            ob_eval = source_obj.evaluated_get(dg)
+            tri_b.append(ob_eval.matrix_world @ ob_eval.data.vertices[idx].co)
+
+        for new_stroke, stroke_data in zip(list(new_strokes), list(self.strokes_data)):
+            world_co_3d = []
+            for hit_location, tri_a in stroke_data:
+                new_loc = barycentric_transform(hit_location, *tri_a, *tri_b)
+                world_co_3d.append(new_loc)
+
+            ## Reproject on plane
+            new_world_co_3d = [intersect_line_plane(origin, p, plane_co, plane_no) for p in world_co_3d]        
+            new_local_co_3d = [co for coord in new_world_co_3d for co in self.gp.matrix_world.inverted() @ coord]
+            new_stroke.points.foreach_set('co', new_local_co_3d)
+            new_stroke.points.update()
+
+classes = (
+    GP_OT_interpolate_stroke_tri,
+)
+
+def register():
+    for c in classes:
+        bpy.utils.register_class(c)
+    
+        
+def unregister():
+    for c in reversed(classes):
+        bpy.utils.unregister_class(c)

interpolate_strokes/operators_velocity.py

@@ -0,0 +1,268 @@
+import bpy
+from time import time
+
+import bpy
+#from bpy_extras.object_utils import world_to_camera_view
+from mathutils import Vector
+from mathutils.kdtree import KDTree
+from math import tan
+
+
+from mathutils.geometry import (barycentric_transform,
+                                intersect_line_plane)
+
+from ..utils import (triangle_normal,
+                    get_gp_draw_plane, load_datablock)
+
+from ..constants import RESOURCES_DIR
+from .operators import GP_OT_interpolate_stroke_base
+
+
+def world_to_camera_view(scene, obj, coord):
+    """
+    Returns the camera space coords for a 3d point.
+    (also known as: normalized device coordinates - NDC).
+
+    Where (0, 0) is the bottom left and (1, 1)
+    is the top right of the camera frame.
+    values outside 0-1 are also supported.
+    A negative 'z' value means the point is behind the camera.
+
+    Takes shift-x/y, lens angle and sensor size into account
+    as well as perspective/ortho projections.
+
+    :arg scene: Scene to use for frame size.
+    :type scene: :class:`bpy.types.Scene`
+    :arg obj: Camera object.
+    :type obj: :class:`bpy.types.Object`
+    :arg coord: World space location.
+    :type coord: :class:`mathutils.Vector`
+    :return: a vector where X and Y map to the view plane and
+       Z is the depth on the view axis.
+    :rtype: :class:`mathutils.Vector`
+    """
+    from mathutils import Vector
+
+    co_local = obj.matrix_world.normalized().inverted() @ coord
+    z = -co_local.z
+
+    camera = obj.data
+    frame = [v for v in camera.view_frame(scene=scene)[:3]]
+    if camera.type != 'ORTHO':
+        if z == 0.0:
+            return Vector((0.5, 0.5, 0.0))
+        else:
+            frame = [-(v / (v.z / z)) for v in frame]
+
+    min_x, max_x = frame[2].x, frame[1].x
+    min_y, max_y = frame[1].y, frame[0].y
+
+    x = (co_local.x - min_x) / (max_x - min_x)
+    y = (co_local.y - min_y) / (max_y - min_y)
+
+    return Vector((x, y, z))
+
+def camera_view_to_world(scene, obj, coord):
+    """Reverse function of world_to_camera_view"""
+    
+    frame = [obj.matrix_world @ co for co in obj.data.view_frame(scene=scene)]
+    
+    x, y, z = coord
+    
+    right_interp = frame[1] + y * (frame[0] - frame[1])
+    # Interpolate along x-axis (left side)
+    left_interp = frame[2] + y * (frame[3] - frame[2])
+    
+    # Interpolate along y-axis
+    return  Vector(left_interp + x * (right_interp - left_interp))
+
+
+class GP_OT_interpolate_stroke_velocity(GP_OT_interpolate_stroke_base):
+    bl_idname = "gp.interpolate_stroke_velocity"
+    bl_label = "Interpolate Stroke"
+    bl_description = 'Interpolate Stroke based on velocity'
+    bl_options = {'REGISTER', 'UNDO'} 
+
+    def invoke(self, context, event):
+        if state := super().invoke(context, event):
+            return state
+
+        if not self.settings.target_object and not self.settings.target_collection:
+            self.report({"ERROR"}, "No collection of object specified")
+            return {"CANCELLED"}
+        
+        scn = bpy.context.scene
+        settings = context.scene.gp_interpo_settings
+
+        ## Prepare context manager
+        attrs = [
+            # (context.view_layer.objects, 'active', self.gp),
+            (context.tool_settings, 'use_keyframe_insert_auto', True),
+            # (bpy.context.scene.render, 'simplify_subdivision', 0),
+            ]
+        self.apply_and_store(attrs)
+                        
+        velocity_mesh = bpy.data.meshes.new('interpolate_velocity')
+        velocity_ob = bpy.data.objects.new('interpolate_velocity', velocity_mesh)
+
+        self.velocity_node_group = load_datablock(RESOURCES_DIR/'nodes.blend', 'Velocity Grid', type='node_groups', link=False)
+
+        instance_col_mod = velocity_ob.modifiers.new('IngestCollection', 'NODES')
+        ingest_node_group = load_datablock(RESOURCES_DIR/'nodes.blend', 'Ingest Collection', type='node_groups', link=False)
+        instance_col_mod.node_group = ingest_node_group
+        instance_col_mod["Socket_3"] = settings.target_object
+        instance_col_mod["Socket_2"] = settings.target_collection
+
+        scn.collection.objects.link(velocity_ob)
+
+        # Apply instance collection modifier
+        dg = bpy.context.evaluated_depsgraph_get()
+        eval_ob = velocity_ob.evaluated_get(dg)
+        eval_data = eval_ob.data.copy()
+
+        velocity_ob.modifiers.remove(instance_col_mod)
+        velocity_ob.data = eval_data
+
+        bpy.data.node_groups.remove(ingest_node_group)
+
+        self.velocity_ob = velocity_ob
+
+        if self.debug:
+            self.scan_time = time()-self.start
+            print(f'Scan time {self.scan_time:.4f}s')
+
+        # Baking Camera
+        self.camera = scn.camera.copy()
+        self.camera.data = self.camera.data.copy()
+        self.camera.animation_data_clear()
+        self.camera.data.animation_data_clear()
+
+        cam_mat = self.camera.matrix_world.copy()
+        self.camera.animation_data_clear()
+        self.camera.parent = None
+        self.camera.matrix_world = cam_mat
+
+        # Store curent gp matrix
+        self.gp_matrix = self.gp.matrix_world.copy()
+
+        # Ensure whole stroke are selected before copy
+
+        bpy.ops.gpencil.select_linked()
+        # Copy stroke selection
+        bpy.ops.gpencil.copy()
+
+        # Jump frame and paste
+        # if self.report_progress:
+        #     context.window_manager.progress_begin(self.frames_to_jump[0], self.frames_to_jump[-1]) # Pgs
+        # context.area.header_text_set('Starting interpolation | Esc: Cancel')
+
+        context.window_manager.modal_handler_add(self)
+        return {'RUNNING_MODAL'}
+
+    def interpolate_frame(self, context):
+        scn = context.scene
+        cam = scn.camera
+        #dg = bpy.context.evaluated_depsgraph_get()
+        target_object = self.settings.target_object
+        target_col = self.settings.target_collection
+        smooth_level = self.settings.smooth_level
+
+        origin = scn.camera.matrix_world.to_translation()
+        plane_co, plane_no = get_gp_draw_plane(self.gp)
+
+        velocity_ob = self.velocity_ob
+        velocity_ob.hide_set(True)
+
+        grid_velocity_mod = velocity_ob.modifiers.new('VelocityGrid', 'NODES')
+        grid_velocity_mod.node_group = self.velocity_node_group
+        grid_velocity_mod["Socket_8"] = target_object
+        grid_velocity_mod["Socket_2"] = target_col
+        grid_velocity_mod["Socket_4"] = self.camera
+        grid_velocity_mod["Socket_5"] = self.camera.data.angle
+        grid_velocity_mod["Socket_6"] = self.camera.data.shift_x
+        grid_velocity_mod["Socket_7"] = self.camera.data.shift_y
+
+        # Apply velocity grid modifier
+        dg = bpy.context.evaluated_depsgraph_get()
+        eval_ob = velocity_ob.evaluated_get(dg)
+        #eval_data = eval_ob.data.copy()
+        grid_ob = bpy.data.objects.new('Velocity Grid Object', eval_ob.data.copy())
+
+        # copy_ob = velocity_ob.copy()
+        # copy_ob.data = copy_ob.data.copy()
+        # scn.collection.objects.link(copy_ob)
+
+        velocity_ob.modifiers.remove(grid_velocity_mod)
+
+        #Create kd tree for finding nearest points
+        kd = KDTree(len(grid_ob.data.vertices))
+
+        points = [0, 0, 0] * len(grid_ob.data.vertices) 
+        grid_ob.data.vertices.foreach_get('co', points)
+
+        for i in range(0, len(points), 3):
+            kd.insert(points[i:i+3], int(i/3))    
+
+        kd.balance()
+
+        bpy.ops.gpencil.paste(type='LAYER')
+        
+        ## List of newly pasted strokes (using range)
+        new_strokes = [s for l in self.layers for s in l.active_frame.strokes if s.select]
+
+        velocity_attr = grid_ob.data.attributes["velocity"].data
+
+        for stroke in new_strokes:
+            points = [0, 0, 0] * len(stroke.points) 
+            stroke.points.foreach_get('co', points)
+            
+            points_2d = [world_to_camera_view(scn, self.camera, self.gp_matrix @ Vector(points[i:i+3])) for i in range(0, len(points), 3)]
+            points_2d = [Vector((p.x, p.y, 0)) for p in points_2d] # Remove Z component
+            
+            points_velocity = [velocity_attr[kd.find(p)[1]].vector for p in points_2d]
+
+            if smooth_level:
+                # Average of points
+                for i in range(smooth_level + 1):
+                    points_velocity = [
+                        (points_velocity[i] + points_velocity[i + 1]) / 2 if i == 0 else
+                        (points_velocity[i] + points_velocity[i - 1]) / 2 if i == len(points_velocity) - 1 else
+                        (points_velocity[i - 1] + points_velocity[i] + points_velocity[i + 1]) / 3
+                        for i in range(len(points_velocity))
+                    ]
+
+            new_points_3d = [camera_view_to_world(scn, cam, p+vel) for p, vel in zip(points_2d, points_velocity)]
+
+            ## Reproject on plane
+            new_points_3d = [intersect_line_plane(origin, p, plane_co, plane_no) for p in new_points_3d]    
+                    
+            stroke.points.foreach_set('co', [v for p in new_points_3d for v in self.gp.matrix_world.inverted() @p])
+            
+            #new_points_2d = [ p+vel for p, vel in zip(points_2d, points_velocity)]
+            #stroke.points.foreach_set('co', [v for p in new_points_2d for v in self.gp.matrix_world.inverted() @p])
+            stroke.points.update()
+        
+        bpy.data.meshes.remove(grid_ob.data)
+    
+    def exit(self, context, status='INFO', text=None, cancelled=False):
+        out = super().exit(context, status='INFO', text=None, cancelled=False)
+
+        bpy.data.node_groups.remove(self.velocity_node_group)
+        bpy.data.meshes.remove(self.velocity_ob.data)
+        bpy.data.cameras.remove(self.camera.data)
+
+        return out
+
+
+classes = (
+    GP_OT_interpolate_stroke_velocity,
+)
+
+def register():
+    for c in classes:
+        bpy.utils.register_class(c)
+    
+        
+def unregister():
+    for c in reversed(classes):
+        bpy.utils.unregister_class(c)

interpolate_strokes/properties.py

@@ -17,11 +17,13 @@ class GP_PG_interpolate_settings(PropertyGroup):
     method : EnumProperty(
         name='Method',
         items= (
-            ('GEOMETRY', 'Geometry', 'Directly follow underlying geometry', 0),
+            ('VELOCITY', 'Velocity', 'Interpolate based on velocity, works well for point outside geometry', 0),
-            ('BONE', 'Bone', 'Pick an armature bone and follow it', 1),
+            ('GEOMETRY', 'Geometry', 'Directly follow underlying geometry', 1),
-            ('OBJECT', 'Object', 'Directly follow a specific object, even if occluded', 2),
+            ('OBJECT', 'Object Geometry', 'Same as Geometry mode, but target only a specific object, even if occluded (ignore all the others)', 2),
+            ('BONE', 'Bone', 'Pick an armature bone and follow it', 3),
+            ('TRI', 'Triangle', 'Interpolate based on triangle traced manually over geometry', 4)
         ),
-        default='GEOMETRY',
+        default='VELOCITY',
         description='Select method for interpolating strokes'
     )
 
@@ -43,7 +45,7 @@ class GP_PG_interpolate_settings(PropertyGroup):
         name='Mode',
         # Combined ?markers ?
         items= (
-            ('FRAME', 'Frame', 'prev/next scene frame depending on the padding options', 0),
+            ('FRAME', 'Frame', 'prev/next scene frame depending on the step options', 0),
             ('GPKEY', 'GP Key', 'prev/next Grease pencil key', 1)   ,
             ('RIGKEY', 'Rig Key', 'prev/next armatures keys in targeted collection (camera keys are included)', 2),
         ),
@@ -51,7 +53,7 @@ class GP_PG_interpolate_settings(PropertyGroup):
         description='Select how the previous or next frame should be chosen'
     )
 
-    padding : IntProperty(name='Padding',
+    step : IntProperty(name='Step',
         description='Number of frame to jump backward or forward',
         default=2,
         min=1)
@@ -82,6 +84,11 @@ class GP_PG_interpolate_settings(PropertyGroup):
         default=True,
         description='Apply rotation of the bone') # Bone
 
+    #selection: EnumProperty(default='SELECTED', items=[("SELECTED", "Selected", ""), ("ALL", "All", "")], 
+    #                        description="Stroke to interpolate")
+
+    smooth_level: IntProperty(default=2, min=0, max=20, name='Smooth Level')
+
 classes = (
     GP_PG_interpolate_settings,
 )

ui.py

@@ -15,6 +15,7 @@ class GP_PT_interpolate(bpy.types.Panel):
 
         layout = self.layout
         layout.use_property_split = True
+        layout.use_property_decorate = False
         col = layout.column(align=False)
 
         ## Interpolation buttons
@@ -31,11 +32,24 @@ class GP_PT_interpolate(bpy.types.Panel):
             prev_text = f'{scn.frame_preview_start if scn.use_preview_range else scn.frame_start} < {scn.frame_current}'
             next_text = f'{scn.frame_current} > {scn.frame_preview_end if scn.use_preview_range else scn.frame_end}'
 
-
         row = col.row(align=True)
-        row.scale_x = 3
+        row.scale_y = 1.2
-        row.operator("gp.interpolate_stroke", text=prev_text, icon=prev_icon).next = False
+        direction_button_row = row.row(align=True)
-        row.operator("gp.interpolate_stroke", text=next_text, icon=next_icon).next = True
+        direction_button_row.scale_x = 3
+        ops_id = "gp.interpolate_stroke"
+        if settings.method == 'TRI':
+            ops_id = "gp.interpolate_stroke_tri"
+        elif settings.method == 'VELOCITY':
+            ops_id = "gp.interpolate_stroke_velocity"
+
+
+        direction_button_row.operator(ops_id, text=prev_text, icon=prev_icon).next = False
+        direction_button_row.operator(ops_id, text=next_text, icon=next_icon).next = True
+        
+        ## Button for interactive mode (icons: SNAP_INCREMENT, ACTION_TWEAK, CON_ACTION, CENTER_ONLY)
+        interactive_mode_row = row.row()
+        interactive_mode_row.operator(ops_id, text='', icon='ACTION_TWEAK').interactive = True
+
 
         col.prop(settings, 'use_animation', text='Animation')
         col.prop(settings, 'method', text='Method')
@@ -51,9 +65,20 @@ class GP_PT_interpolate(bpy.types.Panel):
         elif settings.method == 'GEOMETRY':
             col.prop(settings, 'search_range')
             col.prop(settings, 'remove_occluded')
+            col.prop(settings, 'smooth_level', text='Smooth')
         
         elif settings.method == 'OBJECT':
+            col.prop(settings, 'search_range')
             col.prop(settings, 'target_object', text='Object')
+            col.prop(settings, 'smooth_level', text='Smooth')
+
+        elif settings.method == 'VELOCITY':
+
+            row = col.row(align=True)
+            row.prop(settings, 'target_collection', text='Collection')
+            row.operator("gp.pick_collection", text='', icon="EYEDROPPER")
+            col.prop(settings, 'target_object', text='Object')
+            col.prop(settings, 'smooth_level', text='Smooth')
 
         col.separator()
         col = layout.column(align=True)
@@ -61,7 +86,7 @@ class GP_PT_interpolate(bpy.types.Panel):
         row.prop(settings, 'mode', expand=True)
 
         if settings.mode == 'FRAME':
-            col.prop(settings, 'padding')
+            col.prop(settings, 'step', text='Step')
 
         if settings.mode == 'RIGKEY':
             col.prop(settings, 'target_collection', text='Collection')
@@ -77,6 +102,17 @@ class GP_PT_interpolate(bpy.types.Panel):
             row.operator('gp.debug_geometry_interpolation_targets', text='Debug points')
             row.operator('gp.debug_geometry_interpolation_targets', text='', icon='X').clear = True
         
+        if context.scene.gp_interpo_settings.method == 'TRI':
+            col.separator()
+            row=layout.row(align=True)
+            wm = bpy.context.window_manager
+            binded = context.object and context.object.type == 'GPENCIL' and wm.get(f'tri_{context.object.name}')
+            txt = 'Show Tri Points' if binded else 'Bind Tri Points'
+            row.operator('gp.bind_points', text=txt, icon='MESH_DATA')
+            if binded:
+                row.operator('gp.bind_points', text='', icon='TRASH').clear = True
+
+
 classes = (
     GP_PT_interpolate,
 )

utils.py

@@ -2,6 +2,9 @@ import bpy
 import math
 
 import numpy as np
+import fnmatch
+import os
+from pathlib import Path
 
 from math import tan
 from mathutils import Vector, Matrix
@@ -35,6 +38,63 @@ class attr_set():
 
 # --- Vector
 
+def load_datablock(filepath, *names, type='objects', link=True, expr=None, assets_only=False, 
+        relative_to=None):
+    """link or append elements from another blender scene
+
+    Args:
+        filepath (str): filepath of the scene to import objects from
+        names (list[str]): names of datablocks to import.
+        type (str, optional): type of data to import.
+            Defaults to 'objects'.
+        link (bool, optional): true if we want to import as link, else append.
+            Defaults to True.
+        expr (str, optional): pattern of names to import.
+            Defaults to None.
+        assets_only (bool, optional):  If true, import only data-blocks marked as assets.
+            Defaults to False.
+        relative_to (str|Path|bool, optionnal): If str or Path and link make path relative to it
+        if False make path absolute, if None use preferences
+            Defaults to None.
+
+    Returns:
+        list|bpy.types.Object: datablocks imported
+    """
+
+    # convert names from tuple to list to get the correct datablock type (blender tricks)
+    names = list(names)
+
+    if isinstance(expr, str):
+        pattern = expr
+        expr = lambda x: fnmatch(x, pattern)
+
+    with bpy.data.libraries.load(str(filepath), link=link, assets_only=assets_only) as (data_from, data_to):
+        datablocks = getattr(data_from, type)
+        if expr:
+            names += [i for i in datablocks if expr(i)]
+        elif not names:
+            names = datablocks
+
+        setattr(data_to, type, names)
+
+        datablocks = getattr(data_to, type)
+
+    if link and datablocks:
+        lib = datablocks[0].library
+        lib_path = os.path.abspath(bpy.path.abspath(lib.filepath))
+
+        if relative_to is False:
+            lib.filepath = lib_path
+        elif isinstance(relative_to, (str, Path)):
+            lib.filepath = bpy.path.relpath(lib_path, start=str(relative_to))
+
+    if len(names) > 1:
+        return datablocks
+
+    if datablocks:
+        return datablocks[0]
+
+
 def triangle_normal(p1, p2, p3):
     """
     Calculate the normal of a triangle given its three vertices.
@@ -53,16 +113,9 @@ def triangle_normal(p1, p2, p3):
     normal.normalize()
     return normal
 
-## Bad normal calculation !!
-# def triangle_normal(a, b, c):
-#     x = a[1] * b[2] - a[2] * b[1]
-#     y = a[2] * b[0] - a[0] * b[2]
-#     z = a[0] * b[1] - a[1] * b[0]
-#     return np.array([x, y, z], dtype='float64')
-
 def plane_coords(size=1):
     v = size * 0.5
-    return np.array([(-v, v, 0), (v, v, 0), (v, -v, 0), (-v, -v, 0)], dtype='float64')
+    return [Vector((-v, v, 0)), Vector((v, v, 0)), Vector((v, -v, 0)), Vector((-v, -v, 0))]
 
 def matrix_transform(coords, matrix):
     coords_4d = np.column_stack((coords, np.ones(len(coords), dtype='float64')))
@@ -84,13 +137,14 @@ def search_square(point, factor=0.05, cam=None):
     depth = vector_magnitude(point - cam.matrix_world.to_translation())
     mat_scale = Matrix.Scale(tan(cam.data.angle * 0.5) * depth * factor, 4)
     
-    return matrix_transform(plane, mat @ mat_scale)
+    final_matrix = mat @ mat_scale
+    return [final_matrix @ co for co in plane]
 
 def get_tri_from_face(hit_location, face_index, object_hit, depsgraph):
     eval_ob = object_hit.evaluated_get(depsgraph)
     face = eval_ob.data.polygons[face_index]
     vertices = [eval_ob.data.vertices[i] for i in face.vertices]
-    face_co = matrix_transform([v.co for v in vertices], eval_ob.matrix_world)
+    face_co = [eval_ob.matrix_world @ v.co for v in vertices]
     
     tri = None
     for tri_idx in tessellate_polygon([face_co]):
@@ -124,7 +178,7 @@ def ray_cast_point(point, origin, depsgraph):
     
     tri, tri_indices = get_tri_from_face(hit_location, face_index, object_hit, depsgraph)
 
-    return object_hit, np.array(hit_location), tri, tri_indices
+    return object_hit, hit_location, tri, tri_indices
 
 def obj_ray_cast(obj, point, origin, depsgraph):
     """Wrapper for ray casting that moves the ray into object space"""
@@ -142,7 +196,7 @@ def obj_ray_cast(obj, point, origin, depsgraph):
     # Get hit location world_space
     hit_location = obj.matrix_world @ location
     tri, tri_indices = get_tri_from_face(hit_location, face_index, obj, depsgraph)
-    return obj, np.array(hit_location), tri, tri_indices
+    return obj, hit_location, tri, tri_indices
 
 
 def empty_at(name='Empty', pos=(0,0,0), collection=None, type='PLAIN_AXES', size=1, show_name=False):
@@ -423,7 +477,7 @@ def get_gp_draw_plane(obj=None):
 
 ## --- Animation
 
-def following_keys(forward=True, all_keys=False) -> list:# -> list[int] | list | None:
+def following_keys(forward=True, animation=False) -> list:# -> list[int] | list | None:
     '''Return a list of int or an empty list'''
     direction = 1 if forward else -1
     cur_frame = bpy.context.scene.frame_current
@@ -437,15 +491,15 @@ def following_keys(forward=True, all_keys=False) -> list:# -> list[int] | list |
 
     frames = []
     if settings.mode == 'FRAME':
-        jump = settings.padding * direction
+        jump = settings.step * direction
-        if all_keys:
+        if animation:
             limit += direction # offset by one for limit to be in range
             return list(range(cur_frame + jump , limit, jump))
 
         else:
             return [cur_frame + jump]
     
-    elif settings.mode == 'GPKEY':
+    if settings.mode == 'GPKEY':
         layers = bpy.context.object.data.layers
         frames = [f.frame_number for l in layers for f in l.frames]
     
@@ -462,30 +516,28 @@ def following_keys(forward=True, all_keys=False) -> list:# -> list[int] | list |
             print(obj.name)
             if not obj.animation_data or not obj.animation_data.action:
                 continue
-            frames += [k.co.x for fc in obj.animation_data.action.fcurves for k in fc.keyframe_points]
+            frames += [round(k.co.x) for fc in obj.animation_data.action.fcurves for k in fc.keyframe_points]
-        
 
     if not frames:
         return []
 
     # Sort frames (invert if looking backward)
+    frames = list(set(frames))
     frames.sort(reverse=not forward)
 
-    if all_keys:
+    if animation:
-        frames = list(set(frames))
         if forward:
-            frame_list = [int(f) for f in frames if f > cur_frame and f <= limit]
+            frame_list = [f for f in frames if cur_frame < f <= limit]
         else:
-            frame_list =  [int(f) for f in frames if f < cur_frame and f >= limit]
+            frame_list =  [f for f in frames if limit <= f < cur_frame]
         return frame_list
 
+    ## Single frame
     if forward:
-        new = next((f for f in frames if f > cur_frame), None)
+        frame_list = next(([f] for f in frames if f > cur_frame), [])
     else:
-        new = next((f for f in frames if f < cur_frame), None)
+        frame_list = next(([f] for f in frames if f < cur_frame), [])
-    if new is None:
+    return frame_list
-        return []
-    return [int(new)]
 
 
 def index_list_from_bools(bool_list) -> list: