import bpy
import bmesh



#
# experiment to convert armature deformations into shape keys.
#
# click the Run Script button over and over to add another shape key to the active object and advance the frame.
#



def getSelectedObjects():
    rval = []
    for obj in bpy.context.scene.objects:
        if obj.select:
            rval.append(obj)
    return rval


def setSubtract(bigger, smaller):
    rval = []
    for x in bigger:
        if not x in smaller:
            rval.append(x)
    return rval


def applyBoneParentMatrix(obj):
        m2 = obj.matrix_world
        obj.parent = None
        obj.matrix_world =m2

def applyOneArmature(tgt, skn, ghost):
    for obj in bpy.context.scene.objects:
        obj.select = (obj==tgt)

    scn = bpy.context.scene

    bpy.ops.object.duplicate()
    o2 =scn.objects.active

    bpy.ops.object.modifier_apply(modifier='Armature')

    newVerts = [v.co for v in o2.data.vertices]

    print ( newVerts)

    if ghost.data.shape_keys is None:
        ghost.shape_key_add("Basis")

    if True or None is ghost.data.shape_keys.key_blocks.get(skn):
        print("adding shape key %s"%skn)
        ghost.shape_key_add(skn)
    else:
        print("shape key %s exists"%skn)

    bm =bmesh.new()
    bm.from_mesh(ghost.data)
    bm.verts.ensure_lookup_table()

    sl = bm.verts.layers.shape.get(skn)
    for i in range(len(bm.verts)):
        bm.verts[i][sl] = newVerts[i]

    bm.to_mesh(ghost.data)

    sk = ghost.data.shape_keys
    sk.key_blocks[skn].value = 1
    sk.keyframe_insert(data_path='key_blocks["%s"].value'%skn, frame=scn.frame_current)
    sk.key_blocks[skn].value = 0
    sk.keyframe_insert(data_path='key_blocks["%s"].value'%skn, frame=scn.frame_current-1)
    sk.keyframe_insert(data_path='key_blocks["%s"].value'%skn, frame=scn.frame_current+1)

    scn.objects.unlink(o2)

    scn.objects.active = tgt


def applyArmatures(tgt, ghost):

    applyOneArmature(tgt, "frame %d"%scn.frame_current , ghost)

def applyArmatures1(tgt):

    applyOneArmature(tgt, "frame %d"%scn.frame_current )

    objs = getSelectedObjects()
    #print(objs)
    old = bpy.context.scene.objects[:]
    bpy.ops.object.duplicate()
    newObjs = setSubtract(bpy.context.scene.objects, old)

    for obj in newObjs:
        applyBoneParentMatrix(obj)

        obj.select = False
        
    for o in objs:
        o.select = True

    print (newObjs)


scn = bpy.context.scene

ghost = scn.objects.get("ghost")
if (ghost is None):
    o2 = scn.objects.active
    bpy.ops.object.duplicate()
    ghost = scn.objects.active
    ghost.name = "ghost"
    scn.objects.active = o2

applyArmatures(scn.objects.active, ghost)

scn.frame_current = scn.frame_current +1