splineik.py 文件源码

def create_spine(start_joint, end_joint, lower_control, upper_control, name='spine'):
    spline_chain, original_chain = shortcuts.duplicate_chain(start_joint, end_joint, prefix='ikSpine_')

    # Create the spline ik
    ikh, effector, curve = cmds.ikHandle(
        name='{0}_ikh'.format(name), solver='ikSplineSolver',
        startJoint=spline_chain[0], endEffector=spline_chain[-1], parentCurve=False,
        simplifyCurve=False)
    effector = cmds.rename(effector, '{0}_eff'.format(name))
    curve = cmds.rename(curve, '{0}_crv'.format(name))

    # Create the joints to skin the curve
    curve_start_joint = cmds.duplicate(start_joint, parentOnly=True, name='{0}CurveStart_jnt'.format(name))
    cmds.parent(curve_start_joint, lower_control)
    curve_end_joint = cmds.duplicate(end_joint, parentOnly=True, name='{0}CurveEnd_jnt'.format(name))
    cmds.parent(curve_end_joint, upper_control)

    # Skin curve
    cmds.skinCluster(curve_start_joint, curve_end_joint, curve, name='{0}_scl'.format(name), tsb=True)

    # Create stretch network
    curve_info = cmds.arclen(curve, constructionHistory=True)
    mdn = cmds.createNode('multiplyDivide', name='{0}Stretch_mdn'.format(name))
    cmds.connectAttr('{0}.arcLength'.format(curve_info), '{0}.input1X'.format(mdn))
    cmds.setAttr('{0}.input2X'.format(mdn), cmds.getAttr('{0}.arcLength'.format(curve_info)))
    cmds.setAttr('{0}.operation'.format(mdn), 2)  # Divide

    # Connect to joints
    for joint in spline_chain[1:]:
        tx = cmds.getAttr('{0}.translateX'.format(joint))
        mdl = cmds.createNode('multDoubleLinear', name='{0}Stretch_mdl'.format(joint))
        cmds.setAttr('{0}.input1'.format(mdl), tx)
        cmds.connectAttr('{0}.outputX'.format(mdn), '{0}.input2'.format(mdl))
        cmds.connectAttr('{0}.output'.format(mdl), '{0}.translateX'.format(joint))

    # Setup advanced twist
    cmds.setAttr('{0}.dTwistControlEnable'.format(ikh), True)
    cmds.setAttr('{0}.dWorldUpType'.format(ikh), 4)  # Object up
    cmds.setAttr('{0}.dWorldUpAxis'.format(ikh), 0)  # Positive Y Up
    cmds.setAttr('{0}.dWorldUpVectorX'.format(ikh), 0)
    cmds.setAttr('{0}.dWorldUpVectorY'.format(ikh), 1)
    cmds.setAttr('{0}.dWorldUpVectorZ'.format(ikh), 0)
    cmds.setAttr('{0}.dWorldUpVectorEndX'.format(ikh), 0)
    cmds.setAttr('{0}.dWorldUpVectorEndY'.format(ikh), 1)
    cmds.setAttr('{0}.dWorldUpVectorEndZ'.format(ikh), 0)
    cmds.connectAttr('{0}.worldMatrix[0]'.format(lower_control), '{0}.dWorldUpMatrix'.format(ikh))
    cmds.connectAttr('{0}.worldMatrix[0]'.format(upper_control), '{0}.dWorldUpMatrixEnd'.format(ikh))

    # Constrain original chain back to spline chain
    for ik_joint, joint in zip(spline_chain, original_chain):
        if joint == end_joint:
            cmds.pointConstraint(ik_joint, joint, mo=True)
            cmds.orientConstraint(upper_control, joint, mo=True)
        else:
            cmds.parentConstraint(ik_joint, joint)