New triangle interpolation method and fixes

- Triangle mode:
  - Add bind modal to set points
  - interpolate based on user defined
triangle bound to geometry
- changed: in geometry mode, points out of geometry should follow more consistantly (needs more testing)
- Better method names is UI
- fix : error when strokes are not fully selected

__init__.py

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

interpolate_strokes/__init__.py

@@ -1,13 +1,15 @@
 from gp_interpolate.interpolate_strokes import (operators,
                                                 properties,
                                                 debug,
+                                                bind_points,
                                                 #interpolate_simple
                                                 )
 
 modules = (
     properties,
     operators,
-    debug
+    debug,
+    bind_points,
     #interpolate_simple,
 )
 

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

@@ -75,6 +75,12 @@ class GP_OT_interpolate_stroke(bpy.types.Operator):
         self.frames_to_jump = None
         self.cancelled = False
 
+        ## 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)
+
         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')
@@ -127,14 +133,16 @@ class GP_OT_interpolate_stroke(bpy.types.Operator):
             # (frame: {self.frames_to_jump[self.loop_count]})
 
         if self.status == 'START':
+            if self.settings.method == 'TRI' and not context.window_manager.get(f'tri_{self.gp.name}'):
+                self.exit_modal(context, status='ERROR', text='Need to bind coordinate first. Use "Bind Tri Point" button')
+                return {'CANCELLED'}
+
             scn = bpy.context.scene
             ## Determine on what key/keys to jump
             self.frames_to_jump = following_keys(forward=self.next, all_keys=self.settings.use_animation)
             if not len(self.frames_to_jump):
                 self.exit_modal(context, status='WARNING', text='No keyframe available in this direction')
                 return {'CANCELLED'}
-            # print('self.frames_to_jump: ', self.frames_to_jump)
-            
             self.gp = context.object
 
             # matrix = np.array(self.gp.matrix_world, dtype='float64')
@@ -154,6 +162,7 @@ class GP_OT_interpolate_stroke(bpy.types.Operator):
                 self.exit_modal(context, status='ERROR', text='No active frame')
                 return {'CANCELLED'}
 
+            ## Get strokes to interpolate
             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
@@ -169,6 +178,7 @@ class GP_OT_interpolate_stroke(bpy.types.Operator):
             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:
                     self.exit_modal(context, status='ERROR', text='No Bone selected')
@@ -197,12 +207,6 @@ class GP_OT_interpolate_stroke(bpy.types.Operator):
                 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
@@ -257,6 +261,20 @@ class GP_OT_interpolate_stroke(bpy.types.Operator):
                 # Override collection
                 col = intercol
             
+            if self.settings.method == 'TRI':
+                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.object_hit_source = object_hit = [bpy.context.scene.objects.get(point_dict[str(i)]['object']) for i in range(3)]
+                self.tri_indices_source = tri_indices = [point_dict[str(i)]['index'] for i in range(3)] # List of vertices index corresponding to tri coordinates
+                
+                tri = []
+                dg = bpy.context.evaluated_depsgraph_get()
+                for source_obj, idx in zip(object_hit, tri_indices):
+                    ob_eval = source_obj.evaluated_get(dg)
+                    tri.append(ob_eval.matrix_world @ ob_eval.data.vertices[idx].co)
+
             dg = bpy.context.evaluated_depsgraph_get()
             self.strokes_data = []
 
@@ -271,6 +289,17 @@ class GP_OT_interpolate_stroke(bpy.types.Operator):
                 stroke_data = []
                 for i, point in enumerate(stroke.points):
                     point_co_world = world_co_3d[i]
+                    
+                    if self.settings.method == 'TRI':
+                        ## 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))
+
+                        # In this case object_hit is a list of object !
+                        stroke_data.append((stroke, point_co_world, object_hit, hit_location, tri, tri_indices))
+                        continue
+
                     if target_obj:
                         object_hit, hit_location, tri, tri_indices = obj_ray_cast(target_obj, Vector(point_co_world), origin, dg)
                     else:
@@ -290,8 +319,18 @@ class GP_OT_interpolate_stroke(bpy.types.Operator):
                                     object_hit, hit_location, tri, tri_indices = ray_cast_point(square_co, origin, dg)
 
                                 if object_hit:
-                                    ## 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))
+
+                                    ## 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
+
                                     found = True
                                     # print(f'{si}:{i} iteration {iteration}') # Dbg
                                     break
@@ -318,6 +357,7 @@ class GP_OT_interpolate_stroke(bpy.types.Operator):
                 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()
 
             # Jump frame and paste
@@ -348,13 +388,21 @@ class GP_OT_interpolate_stroke(bpy.types.Operator):
                 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):]
 
+                if self.settings.method == 'TRI':
+                    ## All points have the same new frame triangle (tri_b)
+                    tri_b = []
+                    for source_obj, idx in zip(self.object_hit_source, self.tri_indices_source):
+                        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(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)
+                        if not self.settings.method == 'TRI':
-                        tri_b = [eval_ob.data.vertices[i].co for i in tri_indices]
+                            eval_ob = object_hit.evaluated_get(dg)
-                        tri_b = matrix_transform(tri_b, eval_ob.matrix_world)
+                            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:

interpolate_strokes/properties.py

@@ -18,8 +18,9 @@ class GP_PG_interpolate_settings(PropertyGroup):
         name='Method',
         items= (
             ('GEOMETRY', 'Geometry', 'Directly follow underlying geometry', 0),
-            ('BONE', 'Bone', 'Pick an armature bone and follow it', 1),
+            ('OBJECT', 'Object Geometry', 'Same as Geometry mode, but target only a specific object, even if occluded (ignore all the others)', 1),
-            ('OBJECT', 'Object', 'Directly follow a specific object, even if occluded', 2),
+            ('BONE', 'Bone', 'Pick an armature bone and follow it', 2),
+            ('TRI', 'Triangle', 'Interpolate based on triangle traced manually over geometry', 3),
         ),
         default='GEOMETRY',
         description='Select method for interpolating strokes'

ui.py

@@ -53,6 +53,7 @@ class GP_PT_interpolate(bpy.types.Panel):
             col.prop(settings, 'remove_occluded')
         
         elif settings.method == 'OBJECT':
+            col.prop(settings, 'search_range')
             col.prop(settings, 'target_object', text='Object')
 
         col.separator()
@@ -77,6 +78,17 @@ 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

@@ -124,7 +124,7 @@ 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 +142,7 @@ 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):