bm_changeShape.py

import maya.cmds as cmds

# replaces the selected transform's shape with a new one

def changeShape(obj=None,type=None):
    shapeTypes = ["cube", "circle", "square", "triangle"]
    if type not in shapeTypes:
        print "Shape type not recognized"
        return
    if not obj:
        obj = cmds.ls(sl=1)
    if cmds.objectType(obj) != "transform":
        print "Error: Objects must be of type \"transform\" "
        return
    objShape = cmds.pickWalk(obj, d="down")
    # get shape's bounding box for its world scale
    # bounding box is ony for the SHAPE's bounding box.

    # use shape's Center attribute (bounding box center) for new obj's translate
    # use shape's boundingBoxSize attr for new obj's scale.
    # *** this gives some really interesting behavior that could come in handy elsewhere!
    # * the boundingBoxSize seems to be incorrect, but it is actually using
    # the CVs as the full size and not the final approximated curve

    # make our new shape
    if type == "cube":
        newObj = cmds.polyCube(n=obj[0] + "_newShape", ch=0)
        cmds.connectAttr(objShape[0] + ".center", newObj[0] + ".translate")
        cmds.connectAttr(objShape[0] + ".boundingBox.boundingBoxSize", newObj[0] + ".scale")
        cmds.disconnectAttr(objShape[0] + ".center", newObj[0] + ".translate")
        cmds.disconnectAttr(objShape[0] + ".boundingBox.boundingBoxSize", newObj[0] + ".scale")

        # for a 3d shape change like a cube, it will be flattened to 0 on the Y axis unless we do something about that..
        # Here we just set it to the same value of the sX value to keep it square, but if the object we're querying
        # had an irregular shape, we'd have to manually make some changes here
        # Also this assumes that the object has a 0 value in the Y axis, which might not always be the case.
        # If the rotations have been brought on by the objet's rotate values, it will inherit those
        if cmds.getAttr(newObj[0] + ".scaleX") < .0001 and cmds.getAttr(newObj[0] + ".scaleY") > .0001:
            cmds.setAttr(newObj[0] + ".scaleX", cmds.getAttr(newObj[0] + ".scaleY"))
        elif cmds.getAttr(newObj[0] + ".scaleX") < .0001 and cmds.getAttr(newObj[0] + ".scaleZ") > .0001:
            cmds.setAttr(newObj[0] + ".scaleX", cmds.getAttr(newObj[0] + ".scaleZ"))
        elif cmds.getAttr(newObj[0] + ".scaleY") < .0001 and cmds.getAttr(newObj[0] + ".scaleZ") > .0001:
            cmds.setAttr(newObj[0] + ".scaleY", cmds.getAttr(newObj[0] + ".scaleZ"))
        elif cmds.getAttr(newObj[0] + ".scaleY") < .0001 and cmds.getAttr(newObj[0] + ".scaleX") > .0001:
            cmds.setAttr(newObj[0] + ".scaleY", cmds.getAttr(newObj[0] + ".scaleX"))
        elif cmds.getAttr(newObj[0] + ".scaleZ") < .0001 and cmds.getAttr(newObj[0] + ".scaleX") > .0001:
            cmds.setAttr(newObj[0] + ".scaleZ", cmds.getAttr(newObj[0] + ".scaleX"))
        elif cmds.getAttr(newObj[0] + ".scaleZ") < .0001 and cmds.getAttr(newObj[0] + ".scaleY") > .0001:
            cmds.setAttr(newObj[0] + ".scaleZ", cmds.getAttr(newObj[0] + ".scaleY"))
        # make the cube not renderable

        newObjShape = cmds.pickWalk(newObj,d="down")[0]
        cmds.setAttr(newObjShape + ".overrideEnabled",1)
        cmds.setAttr(newObjShape + ".overrideShading",0)
        cmds.setAttr(newObjShape + ".castsShadows",0)
        cmds.setAttr(newObjShape + ".receiveShadows",0)
        cmds.setAttr(newObjShape + ".primaryVisibility",0)

    elif type == "circle":
        newObj = cmds.circle(n=obj[0] + "_newShape", ch=0, nr=(0, 1, 0))
        cmds.connectAttr(objShape[0] + ".center", newObj[0] + ".translate")
        cmds.connectAttr(objShape[0] + ".boundingBox.boundingBoxSize", newObj[0] + ".scale")
        cmds.disconnectAttr(objShape[0] + ".center", newObj[0] + ".translate")
        cmds.disconnectAttr(objShape[0] + ".boundingBox.boundingBoxSize", newObj[0] + ".scale")
        # it ends up doubling the radius we want so let's fix that
        cmds.setAttr(newObj[0] + ".scaleX", cmds.getAttr(newObj[0] + ".scaleX") / 2)
        cmds.setAttr(newObj[0] + ".scaleY", cmds.getAttr(newObj[0] + ".scaleY") / 2)
        cmds.setAttr(newObj[0] + ".scaleZ", cmds.getAttr(newObj[0] + ".scaleZ") / 2)

    elif type == "square":
        newObj = cmds.circle(n=obj[0] + "_newShape", ch=0, nr=(0, 1, 0), degree=1, sections=4)
        cmds.xform(newObj, ro=(0, 45, 0))
        cmds.connectAttr(objShape[0] + ".center", newObj[0] + ".translate")
        cmds.connectAttr(objShape[0] + ".boundingBox.boundingBoxSize", newObj[0] + ".scale")
        cmds.disconnectAttr(objShape[0] + ".center", newObj[0] + ".translate")
        cmds.disconnectAttr(objShape[0] + ".boundingBox.boundingBoxSize", newObj[0] + ".scale")
        # it ends up doubling the radius we want so let's fix that
        cmds.setAttr(newObj[0] + ".scaleX", cmds.getAttr(newObj[0] + ".scaleX") / 2)
        cmds.setAttr(newObj[0] + ".scaleY", cmds.getAttr(newObj[0] + ".scaleY") / 2)
        cmds.setAttr(newObj[0] + ".scaleZ", cmds.getAttr(newObj[0] + ".scaleZ") / 2)

    elif type == "triangle":
        newObj = cmds.circle(n=obj[0] + "_newShape", ch=0, nr=(0, 1, 0), degree=1, sections=3)
        cmds.xform(newObj, ro=(0, 180, 0))
        cmds.connectAttr(objShape[0] + ".center", newObj[0] + ".translate")
        cmds.connectAttr(objShape[0] + ".boundingBox.boundingBoxSize", newObj[0] + ".scale")
        cmds.disconnectAttr(objShape[0] + ".center", newObj[0] + ".translate")
        cmds.disconnectAttr(objShape[0] + ".boundingBox.boundingBoxSize", newObj[0] + ".scale")
        # it ends up doubling the radius we want so let's fix that
        cmds.setAttr(newObj[0] + ".scaleX", cmds.getAttr(newObj[0] + ".scaleX") / 2)
        cmds.setAttr(newObj[0] + ".scaleY", cmds.getAttr(newObj[0] + ".scaleY") / 2)
        cmds.setAttr(newObj[0] + ".scaleZ", cmds.getAttr(newObj[0] + ".scaleZ") / 2)

    # finally, we can do the parenting
    newObjShape = cmds.pickWalk(newObj, d="down")
    # freeze the new object's transformations
    cmds.makeIdentity(newObj, apply=1, t=1, r=1, s=1)
    cmds.parent(newObjShape, obj, r=1, s=1)

    # finally, delete the old shape and our newObj's transform node
    cmds.delete(objShape, newObj)