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# <pep8-80 compliant>

bl_info = {
    "name": "Corrective Shape Keys",
    "author": "Ivo Grigull (loolarge), Tal Trachtman", "Tokikake"
    "version": (1, 1, 1),
    "blender": (2, 80, 0),
    "location": "Object Data > Shape Keys Specials or Search",
    "description": "Creates a corrective shape key for the current pose",
    "doc_url": "{BLENDER_MANUAL_URL}/addons/animation/corrective_shape_keys.html",
    "category": "Animation",
}

"""
This script transfer the shape from an object (base mesh without
modifiers) to another object with modifiers (i.e. posed Armature).
Only two objects must be selected.
The first selected object will be added to the second selected
object as a new shape key.

- Original 2.4x script by Brecht
- Unpose-function reused from a script by Tal Trachtman in 2007
  http://www.apexbow.com/randd.html
- Converted to Blender 2.5 by Ivo Grigull
- Converted to Blender 2.8 by Tokikake
("fast" option was removed, add new "delta" option
which count currently used shape key values of armature mesh when transfer)

Limitations and new delta option for 2.8
- Target mesh may not have any transformation at object level,
  it will be set to zero.

- new "delta" option usage, when you hope to make new shape-key with keep currently visible other shape keys value.
 it can generate new shape key, with value as 1.00. then deform target shape as source shape with keep other shape key values relative.

- If overwrite shape key,<select active shape key of target as non "base shape">
 current shape key value is ignored and turn as 1.00.

 then if active shape key was driven (bone rotation etc), you may get un-expected result. When transfer, I recommend, keep set active-shape key as base. so transferred shape key do not "overwrite". but generate new shape key.
 if active-shape key have no driver, you can overwrite it (but as 1.00 value )
"""


import bpy
from mathutils import Vector, Matrix

iterations = 20
threshold = 1e-16

def update_mesh(ob):
    depth = bpy.context.evaluated_depsgraph_get()
    depth.update()
    ob.update_tag()
    bpy.context.view_layer.update()
    ob.data.update()


def reset_transform(ob):
    ob.matrix_local.identity()

# this version is for shape_key data
def extract_vert_coords(verts):
    return [v.co.copy() for v in verts]

def extract_mapped_coords(ob, shape_verts):
    depth = bpy.context.evaluated_depsgraph_get()
    eobj = ob.evaluated_get(depth)
    mesh = bpy.data.meshes.new_from_object(eobj)

    # cheating, the original mapped verts happen
    # to be at the end of the vertex array
    verts = mesh.vertices
    #arr = [verts[i].co.copy() for i in range(len(verts) - totvert, len(verts))]
    arr = [verts[i].co.copy() for i in range(0, len(verts))]
    mesh.user_clear()
    bpy.data.meshes.remove(mesh)
    update_mesh(ob)
    return arr



def apply_vert_coords(ob, mesh, x):
    for i, v in enumerate(mesh):
        v.co = x[i]
    update_mesh(ob)


def func_add_corrective_pose_shape(source, target, flag):

    ob_1 = target
    mesh_1 = target.data
    ob_2 = source
    mesh_2 = source.data

    reset_transform(target)

    # If target object doesn't have Base shape key, create it.
    if not mesh_1.shape_keys:
        basis = ob_1.shape_key_add()
        basis.name = "Basis"
        update_mesh(ob_1)
        ob_1.active_shape_key_index = 0
    ob_1.show_only_shape_key = False
    key_index = ob_1.active_shape_key_index
    print(ob_1)
    print(ob_1.active_shape_key)
    active_key_name = ob_1.active_shape_key.name

    if (flag == True):
    # Make mix shape key from currently used shape keys
        if not key_index == 0:
            ob_1.active_shape_key.value = 0
        mix_shape = ob_1.shape_key_add(from_mix = True)
        mix_shape.name = "Mix_shape"
        update_mesh(ob_1)
        keys = ob_1.data.shape_keys.key_blocks.keys()
        ob_1.active_shape_key_index = keys.index(active_key_name)

    print("active_key_name: ", active_key_name)

    if key_index == 0:
        new_shapekey = ob_1.shape_key_add()
        new_shapekey.name = "Shape_" + ob_2.name
        update_mesh(ob_1)
        keys = ob_1.data.shape_keys.key_blocks.keys()
        ob_1.active_shape_key_index = keys.index(new_shapekey.name)

    # else, the active shape will be used (updated)

    ob_1.show_only_shape_key = True

    vgroup = ob_1.active_shape_key.vertex_group
    ob_1.active_shape_key.vertex_group = ""

    #mesh_1_key_verts = mesh_1.shape_keys.key_blocks[key_index].data
    mesh_1_key_verts = ob_1.active_shape_key.data

    x = extract_vert_coords(mesh_1_key_verts)

    targetx = extract_vert_coords(mesh_2.vertices)

    for iteration in range(0, iterations):
        dx = [[], [], [], [], [], []]

        mapx = extract_mapped_coords(ob_1, mesh_1_key_verts)

        # finite differencing in X/Y/Z to get approximate gradient
        for i in range(0, len(mesh_1.vertices)):
            epsilon = (targetx[i] - mapx[i]).length

            if epsilon < threshold:
                epsilon = 0.0

            dx[0] += [x[i] + 0.5 * epsilon * Vector((1, 0, 0))]
            dx[1] += [x[i] + 0.5 * epsilon * Vector((-1, 0, 0))]
            dx[2] += [x[i] + 0.5 * epsilon * Vector((0, 1, 0))]
            dx[3] += [x[i] + 0.5 * epsilon * Vector((0, -1, 0))]
            dx[4] += [x[i] + 0.5 * epsilon * Vector((0, 0, 1))]
            dx[5] += [x[i] + 0.5 * epsilon * Vector((0, 0, -1))]

        for j in range(0, 6):
            apply_vert_coords(ob_1, mesh_1_key_verts, dx[j])
            dx[j] = extract_mapped_coords(ob_1, mesh_1_key_verts)

        # take a step in the direction of the gradient
        for i in range(0, len(mesh_1.vertices)):
            epsilon = (targetx[i] - mapx[i]).length

            if epsilon >= threshold:
                Gx = list((dx[0][i] - dx[1][i]) / epsilon)
                Gy = list((dx[2][i] - dx[3][i]) / epsilon)
                Gz = list((dx[4][i] - dx[5][i]) / epsilon)
                G = Matrix((Gx, Gy, Gz))
                Delmorph = (targetx[i] - mapx[i])
                x[i] += G @ Delmorph

        apply_vert_coords(ob_1, mesh_1_key_verts, x)

    ob_1.show_only_shape_key = True

    if (flag == True):
    # remove delta of mix-shape key values from new shape key
        key_index = ob_1.active_shape_key_index
        active_key_name = ob_1.active_shape_key.name
        shape_data = ob_1.active_shape_key.data
        mix_data = mix_shape.data
        for i in range(0, len(mesh_1.vertices)):
            shape_data[i].co = mesh_1.vertices[i].co + shape_data[i].co - mix_data[i].co
        update_mesh(ob_1)

        ob_1.active_shape_key_index = ob_1.data.shape_keys.key_blocks.keys().index("Mix_shape")
        bpy.ops.object.shape_key_remove()
        ob_1.active_shape_key_index = ob_1.data.shape_keys.key_blocks.keys().index(active_key_name)
        ob_1.data.update()
        ob_1.show_only_shape_key = False

    ob_1.active_shape_key.vertex_group = vgroup

    # set the new shape key value to 1.0, so we see the result instantly
    ob_1.active_shape_key.value = 1.0
    update_mesh(ob_1)



class add_corrective_pose_shape(bpy.types.Operator):
    """Adds first object as shape to second object for the current pose """ \
    """while maintaining modifiers """ \
    """(i.e. anisculpt, avoiding crazy space) Beware of slowness!"""

    bl_idname = "object.add_corrective_pose_shape"
    bl_label = "Add object as corrective pose shape"

    @classmethod
    def poll(cls, context):
        return context.active_object is not None

    def execute(self, context):
        selection = context.selected_objects
        if len(selection) != 2:
            self.report({'ERROR'}, "Select source and target objects")
            return {'CANCELLED'}

        target = context.active_object
        if context.active_object == selection[0]:
            source = selection[1]
        else:
            source = selection[0]

        delta_flag = False

        func_add_corrective_pose_shape(source, target, delta_flag)

        return {'FINISHED'}

class add_corrective_pose_shape_delta (bpy.types.Operator):
    """Adds first object as shape to second object for the current pose """ \
    """while maintaining modifiers and currently used other shape keys""" \
    """with keep other shape key value, generate new shape key which deform to source shape """

    bl_idname = "object.add_corrective_pose_shape_delta"
    bl_label = "Add object as corrective pose shape delta"

    @classmethod
    def poll(cls, context):
        return context.active_object is not None

    def execute(self, context):
        selection = context.selected_objects
        if len(selection) != 2:
            self.report({'ERROR'}, "Select source and target objects")
            return {'CANCELLED'}

        target = context.active_object
        if context.active_object == selection[0]:
            source = selection[1]
        else:
            source = selection[0]

        delta_flag = True

        func_add_corrective_pose_shape(source, target, delta_flag)

        return {'FINISHED'}


def func_object_duplicate_flatten_modifiers(context, ob):
    depth = bpy.context.evaluated_depsgraph_get()
    eobj = ob.evaluated_get(depth)
    mesh = bpy.data.meshes.new_from_object(eobj)
    name = ob.name + "_clean"
    new_object = bpy.data.objects.new(name, mesh)
    new_object.data = mesh
    bpy.context.collection.objects.link(new_object)
    return new_object


class object_duplicate_flatten_modifiers(bpy.types.Operator):
    #Duplicates the selected object with modifiers applied

    bl_idname = "object.object_duplicate_flatten_modifiers"
    bl_label = "Duplicate and apply all"

    @classmethod
    def poll(cls, context):
        return context.active_object is not None

    def execute(self, context):
        obj_act = context.active_object

        new_object = func_object_duplicate_flatten_modifiers(context, obj_act)

        # setup the context
        bpy.ops.object.select_all(action='DESELECT')

        context.view_layer.objects.active = new_object
        new_object.select_set(True)

        return {'FINISHED'}

#these old functions and class not work correctly just keep code for others try to edit

def unposeMesh(meshObToUnpose, obj, armatureOb):
    psdMeshData = meshObToUnpose

    psdMesh = psdMeshData
    I = Matrix()  # identity matrix

    meshData =obj.data
    mesh = meshData

    armData = armatureOb.data

    pose = armatureOb.pose
    pbones = pose.bones

    for index, v in enumerate(mesh.vertices):
        # above is python shortcut for:index goes up from 0 to tot num of
        # verts in mesh, with index incrementing by 1 each iteration

        psdMeshVert = psdMesh[index]

        listOfBoneNameWeightPairs = []
        for n in mesh.vertices[index].groups:
            try:
                name = obj.vertex_groups[n.group].name
                weight = n.weight
                is_bone = False
                for i in armData.bones:
                    if i.name == name:
                        is_bone = True
                        break
                # ignore non-bone vertex groups
                if is_bone:
                    listOfBoneNameWeightPairs.append([name, weight])
            except:
                print('error')
                pass

        weightedAverageDictionary = {}
        totalWeight = 0
        for pair in listOfBoneNameWeightPairs:
            totalWeight += pair[1]

        for pair in listOfBoneNameWeightPairs:
            if totalWeight > 0:  # avoid divide by zero!
                weightedAverageDictionary[pair[0]] = pair[1] / totalWeight
            else:
                weightedAverageDictionary[pair[0]] = 0

        # Matrix filled with zeros
        sigma = Matrix()
        sigma.zero()

        list = []
        for n in pbones:
            list.append(n)
        list.reverse()

        for pbone in list:
            if pbone.name in weightedAverageDictionary:
                #~ print("found key %s", pbone.name)
                vertexWeight = weightedAverageDictionary[pbone.name]
                m = pbone.matrix_channel.copy()
                #m.transpose()
                sigma += (m - I) * vertexWeight

            else:
                pass
                #~ print("no key for bone " + pbone.name)

        sigma = I + sigma
        sigma.invert()
        psdMeshVert.co = sigma @ psdMeshVert.co
        obj.update_tag()
        bpy.context.view_layer.update()



def func_add_corrective_pose_shape_fast(source, target):
    reset_transform(target)

    # If target object doesn't have Basis shape key, create it.
    if not target.data.shape_keys:
        basis = target.shape_key_add()
        basis.name = "Basis"
        target.data.update()

    key_index = target.active_shape_key_index

    if key_index == 0:

        # Insert new shape key
        new_shapekey = target.shape_key_add()
        new_shapekey.name = "Shape_" + source.name

        key_index = len(target.data.shape_keys.key_blocks) - 1
        target.active_shape_key_index = key_index

    # else, the active shape will be used (updated)

    target.show_only_shape_key = True

    shape_key_verts = target.data.shape_keys.key_blocks[key_index].data

    try:
        vgroup = target.active_shape_key.vertex_group
        target.active_shape_key.vertex_group = ''
    except:
        pass

    # copy the local vertex positions to the new shape
    verts = source.data.vertices
    for n in range(len(verts)):
        shape_key_verts[n].co = verts[n].co
    target.update_tag()
    bpy.context.view_layer.update()
    # go to all armature modifies and unpose the shape
    for n in target.modifiers:
        if n.type == 'ARMATURE' and n.show_viewport:
            #~ print("got one")
            n.use_bone_envelopes = False
            n.use_deform_preserve_volume = False
            n.use_vertex_groups = True
            armature = n.object
            unposeMesh(shape_key_verts, target, armature)
            break

    # set the new shape key value to 1.0, so we see the result instantly
    target.active_shape_key.value = 1.0

    try:
        target.active_shape_key.vertex_group = vgroup
    except:
        pass

    target.show_only_shape_key = False
    target.update_tag()
    bpy.context.view_layer.update()

    target.data.update()





class add_corrective_pose_shape_fast(bpy.types.Operator):
    #Adds 1st object as shape to 2nd object as pose shape (only 1 armature)

    bl_idname = "object.add_corrective_pose_shape_fast"
    bl_label = "Add object as corrective shape faster"

    @classmethod
    def poll(cls, context):
        return context.active_object is not None

    def execute(self, context):
        selection = context.selected_objects
        if len(selection) != 2:
            self.report({'ERROR'}, "Select source and target objects")
            return {'CANCELLED'}

        target = context.active_object
        if context.active_object == selection[0]:
            source = selection[1]
        else:
            source = selection[0]

        func_add_corrective_pose_shape_fast(source, target)

        return {'FINISHED'}



# -----------------------------------------------------------------------------
# GUI

def vgroups_draw(self, context):
    layout = self.layout

    layout.operator("object.object_duplicate_flatten_modifiers",
                    text='Create duplicate for editing')
    layout.operator("object.add_corrective_pose_shape",
                    text='Add as corrective pose-shape (slow, all modifiers)',
                    icon='COPY_ID')  # icon is not ideal
    layout.operator("object.add_corrective_pose_shape_delta",
                    text='Add as corrective pose-shape delta" (slow, all modifiers + other shape key values)',
                    icon='COPY_ID')  # icon is not ideal


def modifiers_draw(self, context):
    pass

classes = (add_corrective_pose_shape, add_corrective_pose_shape_delta, object_duplicate_flatten_modifiers, add_corrective_pose_shape_fast)
def register():
    from bpy.utils import register_class
    for cls in classes:
        register_class(cls)
    bpy.types.MESH_MT_shape_key_context_menu.append(vgroups_draw)
    bpy.types.DATA_PT_modifiers.append(modifiers_draw)


def unregister():
    from bpy.utils import unregister_class
    for cls in reversed(classes):
        unregister_class(cls)
    bpy.types.MESH_MT_shape_key_context_menu.remove(vgroups_draw)
    bpy.types.DATA_PT_modifiers.remove(modifiers_draw)

if __name__ == "__main__":
    register()