Maya command `sets -forceElement` failed cases

forceElement_failed_demo.py

"""

Maya command `sets -forceElement` failed cases

"""

from maya import cmds


CUBE = None
MESH = None
PHONG_SG = None


def _setup():
    """Scene setup for testing
    """
    global CUBE, MESH, PHONG_SG

    cmds.file(new=True, force=True)

    CUBE = cmds.polyCube(constructionHistory=False)[0]
    MESH = cmds.listRelatives(CUBE, shapes=True)[0]
    phong = cmds.shadingNode("phong", asShader=True)
    PHONG_SG = cmds.createNode("shadingEngine", name="phong1SG")
    cmds.connectAttr(phong + ".outColor",
                     PHONG_SG + ".surfaceShader",
                     force=True)
    cmds.connectAttr(PHONG_SG + ".partition",
                     ":renderPartition.sets",
                     nextAvailable=True)
    cmds.setAttr(phong + ".color", 1, 0, 0)


def duplicated_set_member():
    """

    pCubeShape1                          phong1SG
   .------------------------.           .---------------------.
   |                        |           |                     |
   | - instObjGroups[0]     |     .---> @ - dagSetMembers[0]  |
   |     + objectGroups[1]  @ ---*----> @ - dagSetMembers[1]  |
   |                        |           |                     |

    """
    cmds.sets(CUBE + ".f[0]", forceElement=PHONG_SG)

    # Re-produce duplicated objectGroup connections
    conns = cmds.listConnections(MESH,
                                 source=False,
                                 destination=True,
                                 plugs=True,
                                 connections=True,
                                 type="shadingEngine")
    for SRC, dst in zip(conns[::2], conns[1::2]):
        if dst.startswith(PHONG_SG):
            cmds.connectAttr(SRC, PHONG_SG + ".dagSetMembers[1]")
            break

    # RuntimeError raised.
    cmds.sets("pCubeShape1.f[0]", forceElement="initialShadingGroup")


def disconnect_renderpartition_face():
    """Not connected to renderPartition (Face assign)
    """
    # Face assign
    cmds.sets(CUBE + ".f[0]", forceElement=PHONG_SG)
    # Disconnect renderPartition
    cmds.disconnectAttr(PHONG_SG + ".partition",
                        ":renderPartition.sets",
                        nextAvailable=True)

    # Shader not changed, and NO error raised !
    cmds.sets("pCubeShape1.f[0]", forceElement="initialShadingGroup")


def disconnect_renderpartition_object():
    """Not connected to renderPartition (Object assign)
    """
    # Object assign
    cmds.sets(CUBE, forceElement=PHONG_SG)
    # Disconnect renderPartition
    cmds.disconnectAttr(PHONG_SG + ".partition",
                        ":renderPartition.sets",
                        nextAvailable=True)

    # Shader not changed, and RuntimeError raised.
    cmds.sets("pCubeShape1", forceElement="initialShadingGroup")


#
# Run test
#

# Case 1
_setup()  # Don't forget to reset
cmds.evalDeferred("duplicated_set_member()")

# Case 2
_setup()  # Don't forget to reset
cmds.evalDeferred("disconnect_renderpartition_face()")

# Case 3
_setup()  # Don't forget to reset
cmds.evalDeferred("disconnect_renderpartition_object()")