initial parent code

utils.py

@@ -159,6 +159,72 @@ def plane_on_bone(bone, arm=None, cam=None, set_rotation=True, mesh=True):
     plane = plane_coords()
     return matrix_transform(plane, mat @ mat_scale)
 
+def place_object_to_ref_facing_cam(obj, ref_ob, bone=None, cam=None, set_rotation=True):
+    '''
+    obj (Object): the object to place
+    ref_ob (Object): the reference object or armature
+    bone (posebone): reference pose bone
+    arm (optional: Armature): Armature of the pose bone (if not passed found using bone.id_data)
+    cam (optional: Camera) : Camera to align plane to (if not passed use scene camera)
+    set_rotation (bool): rotate the plane on cam view axis according to bone direction in 2d cam space
+    '''
+
+    if cam is None:
+        cam = bpy.context.scene.camera
+    
+    # if ref_ob is None:
+    #     ref_ob = bone.id_data
+
+    mat = cam.matrix_world.copy()
+
+    if set_rotation:
+        if bone:
+            head_world_coord = ref_ob.matrix_world @ bone.head
+            mat.translation = head_world_coord
+
+            ## Apply 2d bone rotation facing camera
+            # Get 2d camera space coords (NDC: normalized device coordinate, 0,0 is bottom-left)
+            head_2d, tail_2d = get_bone_head_tail_2d(bone, cam=cam)
+        else:
+            mat.translation = ref_ob.matrix_world
+            # Get 2d camera space coords (NDC: normalized device coordinate, 0,0 is bottom-left)
+            scene = bpy.context.scene
+            up_vec = Vector((0,0,1))
+            up_vec.rotate(ref_ob.matrix_world)
+            tail_3d = ref_ob.matrix_world.to_translation() + up_vec
+            head_2d = world_to_camera_view(scene, cam, ref_ob.matrix_world.to_translation())
+            tail_2d = world_to_camera_view(scene, cam, tail_3d)
+            ratio = scene.render.resolution_y / scene.render.resolution_x
+            head_2d.y *= ratio
+            tail_2d.y *= ratio
+
+        vec_from_corner_2d = (tail_2d - head_2d).normalized()
+        up_vec_2d = Vector((0,1))
+        # angle = acos(up_vec_2d.dot(vec_from_corner_2d)) ## equivalent but not signed!
+        angle = up_vec_2d.angle_signed(vec_from_corner_2d)
+
+        ## Axis camera aim (seem slightly off)
+        # rot_axis = Vector((0, 0, -1))
+        # rot_axis.rotate(cam.matrix_world)
+
+        ## Axis camera origin -> pivot
+        rot_axis = head_world_coord - cam.matrix_world.translation        
+        mat = rotate_matrix_around_pivot(mat, angle, head_world_coord, rot_axis)
+
+    else:
+        if bone:
+            ## Use mid bone to better follow movement
+            mat.translation = ref_ob.matrix_world @ ((bone.tail + bone.head) / 2) # Mid bone
+        else:
+            mat.translation = ref_ob.matrix_world
+    
+    ## change/adapt scale 
+    # mat_scale = Matrix.Scale(10, 4) # maybe move above mesh condition
+    # mat = mat @ mat_scale
+    obj.matrix_world = mat
+
+
+
 def create_plane(name='Plane', collection=None):
     '''Create a plane using pydata
     collection: link in passed collection, else do not link in scene
@@ -335,3 +401,9 @@ def following_keys(forward=True, all_keys=False) -> list:# -> list[int] | list |
     if new is None:
         return []
     return [int(new)]
+
+
+## -- animation
+
+def is_animated(obj):
+    return True