shift_object_animation_into_armature.py

# shift_object_animation_into_armature.py
# Chris Foster <cdbfoster@gmail.com>
#
# Creates a single armature containing a bone for every selected object and
# copies the movement of the selected objects into the bones.  Sets up proper
# Armature modifiers for each affected object and clears its action.
# To use, select all desired objects and run the script.

from math import radians

import bpy
from mathutils import Matrix, Vector

def snap_cursor_to_selected():
    bpy.context.area.type = 'VIEW_3D'
    bpy.ops.view3d.snap_cursor_to_selected()
    bpy.context.area.type = 'TEXT_EDITOR'

def snap_cursor_to_center():
    bpy.context.area.type = 'VIEW_3D'
    bpy.ops.view3d.snap_cursor_to_center()
    bpy.context.area.type = 'TEXT_EDITOR'

def select_mesh(object):
    for p in object.data.polygons:
        p.select = True

mesh_objects = [object for object in bpy.context.selected_objects if object.type == 'MESH']

snap_cursor_to_center()
bpy.ops.object.add(type='ARMATURE')
armature = bpy.context.active_object

def select_all_bones(deselect=False):
    global armature
    for bone in armature.pose.bones:
        bone.bone.select = not deselect
        bone.bone.select_head = not deselect
        bone.bone.select_tail = not deselect

for mesh_object in mesh_objects:
    bpy.ops.object.select_all(action='DESELECT')
    mesh_object.select = True
    snap_cursor_to_selected()

    bone_name = mesh_object.name + "_arm"

    # Create a bone at the mesh object's location that's an appropriate size
    bpy.ops.object.select_all(action='DESELECT')
    bpy.context.scene.objects.active = armature
    bpy.ops.object.mode_set(mode='EDIT')
    bpy.ops.armature.bone_primitive_add(name=bone_name)
    bone = armature.data.edit_bones[bone_name]
    bone.tail = bone.head + Vector((0.0, 0.0, mesh_object.dimensions.z / 2.0))
    bpy.ops.object.mode_set(mode='OBJECT')

    # Add all vertices of the mesh object into the bone's vertex group
    bpy.context.scene.objects.active = mesh_object
    if bone_name in mesh_object.vertex_groups:
        mesh_object.vertex_groups.active = mesh_object.vertex_groups[bone_name]
    else:
        bpy.ops.object.vertex_group_add()
        vertex_group = mesh_object.vertex_groups.active
        vertex_group.name = bone_name
    select_mesh(mesh_object)
    bpy.ops.object.mode_set(mode='EDIT')
    bpy.ops.object.vertex_group_assign()
    bpy.ops.object.mode_set(mode='OBJECT')

# Key the bones at the positions/rotations of the mesh objects at each frame
bpy.context.scene.objects.active = armature
bpy.ops.object.mode_set(mode='POSE')
select_all_bones()
for frame in range(bpy.context.scene.frame_start, bpy.context.scene.frame_end + 1):
    bpy.context.scene.frame_set(frame)

    for mesh_object in mesh_objects:
        bone = armature.pose.bones[mesh_object.name + "_arm"]
        bone.matrix = mesh_object.matrix_world * Matrix.Rotation(radians(90), 4, 'X')

    bpy.ops.anim.keyframe_insert(type='BUILTIN_KSI_LocRot')

bpy.ops.object.mode_set(mode='OBJECT')

# Add Armature modifiers to the mesh objects and clear their actions
bpy.context.scene.frame_set(bpy.context.scene.frame_start)
for mesh_object in mesh_objects:
    mesh_object.animation_data.action = None
    bpy.context.scene.objects.active = mesh_object
    bpy.ops.object.modifier_add(type='ARMATURE')
    mesh_object.modifiers[-1].object = armature