Blender で IK/FK スナップスクリプト簡易版

ikfk_snap_easy.py

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#
#  This program is free software; you can redistribute it and/or
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#  as published by the Free Software Foundation; either version 2
#  of the License, or (at your option) any later version.
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#  along with this program; if not, write to the Free Software Foundation,
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import bpy
import mathutils

num_bones = 2
armature_name = 'Armature'
ik_bone_name = 'forearm.L'
upper_arm_name = 'upper_arm.L'
ik_target_name = 'IK.L'
ik_pole_name = 'arm_pole.L'

def get_influece_data_path():
    ik_bone = bpy.data.objects[armature_name].pose.bones[ik_bone_name]
    return [ik_bone.constraints["IK"],'influence']

def get_ik_influence(data_path):
    return exec("data_path[0].%s" % data_path[1])

def set_ik_influence(data_path, val):
    exec("data_path[0].%s = %f" % (data_path[1], val))
    
def set_ik(data_path):
    set_ik_influence(data_path, 1.0)
    
def set_fk(data_path):
    set_ik_influence(data_path, 0.0)
    
def set_translation(matrix, loc):
    trs = matrix.decompose()
    rot = trs[1].to_matrix().to_4x4()
    scale = mathutils.Matrix.Scale(1, 4, trs[2])
    return mathutils.Matrix.Translation(loc) * (rot * scale)

#UI
class IKFK_Snap(bpy.types.Panel):
  bl_label = "IK/FK Snap"
  bl_space_type = "VIEW_3D"
  bl_region_type = "UI"
  
  @classmethod
  def poll(self, context):
      return context.object and context.object.type == 'ARMATURE'
    
  def draw(self, context):
    l = self.layout
    influence_data_path = get_influece_data_path()
    l.prop(influence_data_path[0],influence_data_path[1], slider=True)
    l.operator('my.iktofk')
    l.operator('my.fktoik')

class IKtoFKButton(bpy.types.Operator):
    bl_idname = "my.iktofk"
    bl_label = "IK -> FK"
  
    def execute(self, context):
        amt = bpy.data.objects[armature_name]
        ik_bone = amt.pose.bones[ik_bone_name]
        upper_arm = amt.pose.bones[upper_arm_name]
        ik_target = amt.pose.bones[ik_target_name]
        ik_pole = amt.pose.bones[ik_pole_name]

        #copy fk matrix
        set_fk(get_influece_data_path())
        
        #pose update
        bpy.ops.object.mode_set(mode='OBJECT')
        bpy.ops.object.mode_set(mode='POSE')
        
        #set ik target
        ik_target.matrix = set_translation(ik_target.matrix, ik_bone.tail)
        
        #set pole target
        ik_pole.matrix = set_translation(ik_pole.matrix, upper_arm.tail)
        
        return {'FINISHED'}
    
class FKtoIKButton(bpy.types.Operator):
    bl_idname = "my.fktoik"
    bl_label = "FK -> IK"
  
    def execute(self, context):   
        amt = bpy.data.objects[armature_name]
        ik_bone = amt.pose.bones[ik_bone_name]
        upper_arm = amt.pose.bones[upper_arm_name]
        ik_target = amt.pose.bones[ik_target_name]
        ik_pole = amt.pose.bones[ik_pole_name]   
        
        # copy ik matrix
        set_ik(get_influece_data_path())
        
        #pose update
        bpy.ops.object.mode_set(mode='OBJECT')
        bpy.ops.object.mode_set(mode='POSE')
        
        ik_bone_matrixes = []
        it = ik_bone
        for i in range(num_bones):
            ik_bone_matrixes.append(it.matrix)
            it = ik_bone.parent
    
        # set ik matrix to fk bone
        set_fk(get_influece_data_path())
        it = ik_bone
        for i in range(num_bones):
            it.matrix = ik_bone_matrixes[i]
            it = it.parent
        
        return {'FINISHED'}

classes = (
    IKFK_Snap,
    IKtoFKButton,
    FKtoIKButton
)
def register():
    for cls in classes:
        bpy.utils.register_class(cls)
    
def unregister():
    for cls in reverse(classes):
        bpy.utils.unregister_class(cls)
    
if __name__ == "__main__":
    register()