follow bone method

utils.py

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+import bpy
+import math
+
+from mathutils import Vector, Matrix
+from bpy_extras.object_utils import world_to_camera_view
+
+def get_bone_head_tail_2d(posebone, scene=None, cam=None) -> tuple[Vector, Vector]:
+    '''Get 2D vectors in camera view of bone head and tails
+    return tuple of 2d vectors (head_2d and tail_2d) 
+    '''
+    scene = scene or bpy.context.scene
+    cam = cam or scene.camera
+
+    arm = posebone.id_data
+
+    # Get 3D locations of head and tail
+    head_3d = arm.matrix_world @ posebone.head
+    tail_3d = arm.matrix_world @ posebone.tail
+
+    # Convert 3D locations to 2D
+    head_2d = world_to_camera_view(scene, cam, head_3d)
+    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
+    
+    return Vector((head_2d.x, head_2d.y)), Vector((tail_2d.x, tail_2d.y))
+
+
+def rotate_matrix_around_pivot(matrix, angle, pivot, axis):
+    '''Rotate a given matrix by a CW angle around pivot on a given axis
+    matrix (Matrix): the matrix to rotate
+    angle (Float, Radians): the angle in radians
+    pivot (Vector3): the pivot 3D coordinate
+    axis (Vector3): the vector axis of rotation
+    '''
+
+    # Convert angle to radians ?
+    # angle = math.radians(angle)
+
+    # Create a rotation matrix
+    rot_matrix = Matrix.Rotation(angle, 4, axis)
+
+    # Create translation matrices
+    translate_to_origin = Matrix.Translation(-pivot)
+    translate_back = Matrix.Translation(pivot)
+
+    # Combine the transformations : The order of multiplication is important
+    new_matrix = translate_back @ rot_matrix @ translate_to_origin @ matrix
+
+    return new_matrix