scripted/motionTraceCmd.py

#-
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########################################################################
# DESCRIPTION:
#
# Produces the Python command "spMotionTrace".
#
# This plug-in traces the position of an animated object and creates a curve
# showing the object's path.
#
# To use this plug-in, you must first create an object and animate it by setting
# keyframes. An easy way to do this is to just create a primitive, then set several
# keyframes on it.
#
# Once this is done, select the animated object and invoke the spMotionTrace command.
#
# Options:
#
#   s=<frame>       The start frame. Default to 1.
#   e=<frame>       The end frame. Default to 60.
#   b=<frame>       The by frame. Default to 1.
#
# Example:
#
#   From Python:
#       import maya
#       maya.cmds.spMotionTrace(s=1, e=100, b=2)
#
#   From Mel:
#       spMotionTrace -s 1 -e 100 -b 2
#
# The object will move along its animated path under control of the plug-in and when the
# animation is complete, the plug-in will draw a curve in the scene that represents
# the motion path of the object. 
#
########################################################################

#
#   Creation Date:   27 September 2006
#

import maya.OpenMaya as OpenMaya
import maya.OpenMayaMPx as OpenMayaMPx
import math, sys

kPluginCmdName="spMotionTrace"

kStartFlag = "-s"
kStartLongFlag = "-startFrame"
kEndFlag = "-e"
kEndLongFlag = "-endFrame"
kByFlag = "-b"
kByLongFlag = "-byFrame"

# command
class motionTrace(OpenMayaMPx.MPxCommand):
    def __init__(self):
        OpenMayaMPx.MPxCommand.__init__(self)
        # setup private data members
        self.__start = 1
        self.__end = 60
        self.__by = 1


    def doIt(self, args):
        """
        This method is called from script when this command is called.
        It should set up any class data necessary for redo/undo,
        parse any given arguments, and then call redoIt.
        """
        argData = OpenMaya.MArgDatabase(self.syntax(), args)

        if argData.isFlagSet(kStartFlag):
            self.__start = argData.flagArgumentInt(kStartFlag, 0)
        if argData.isFlagSet(kEndFlag):
            self.__end = argData.flagArgumentInt(kEndFlag, 0)
        if argData.isFlagSet(kByFlag):
            self.__by = argData.flagArgumentInt(kByFlag, 0)

        self.redoIt()


    def redoIt(self):
        """
        This method performs the action of the command.
        This method iterates over all selected items and
        prints out connected plug and dependency node type
        information.
        """
        picked = OpenMaya.MObjectArray()
        dependNode = OpenMaya.MObject()     # Selected dependency node

        # Create a selection list iterator
        slist = OpenMaya.MSelectionList()
        OpenMaya.MGlobal.getActiveSelectionList(slist)
        iter = OpenMaya.MItSelectionList(slist)

        # Iterate over all selected dependency nodes
        # and save them in a list
        while not iter.isDone():
            # Get the selected dependency node
            iter.getDependNode(dependNode)
            picked.append(dependNode)
            iter.next()

        # sample the animation using start, end, by values
        pointArrays = [ OpenMaya.MPointArray() for i in range(picked.length()) ]

        time = self.__start
        while (time <= self.__end):
            timeval = OpenMaya.MTime(time)
            OpenMaya.MGlobal.viewFrame(timeval)

            # Iterate over selected dependency nodes
            for i in range(picked.length()):
                # Get the selected dependency node
                dependNode = picked[i]

                # Create a function set for the dependency node
                fnDependNode = OpenMaya.MFnDependencyNode(dependNode)

                # Get the translation attribute values
                txAttr = fnDependNode.attribute("translateX")
                txPlug = OpenMaya.MPlug(dependNode, txAttr)
                tx = txPlug.asDouble()

                tyAttr = fnDependNode.attribute("translateY")
                tyPlug = OpenMaya.MPlug(dependNode, tyAttr)
                ty = tyPlug.asDouble()

                tzAttr = fnDependNode.attribute("translateZ")
                tzPlug = OpenMaya.MPlug(dependNode, tzAttr)
                tz = tzPlug.asDouble()

                print "adding", tx, ty, tz, "\n"
                pointArrays[i].append(OpenMaya.MPoint(tx, ty, tz))

            time += self.__by

        # make a path curve for each selected object
        for i in range(picked.length()):
            self.__jMakeCurve(pointArrays[i])


    def __jMakeCurve(self, cvs):
        """
        Make a degree 1 curve from the given CVs.
        
        Note that in Python, a double underscore in front of a member name
        make the method "private" to the class through name-mangling
        """
        deg = 1
        knots = OpenMaya.MDoubleArray()

        for i in range(cvs.length()):
            knots.append(i)

        # Now create the curve
        nullObj = OpenMaya.MObject()
        curveFn = OpenMaya.MFnNurbsCurve()
        curveFn.create(cvs, knots, deg, OpenMaya.MFnNurbsCurve.kOpen, False, False, nullObj)


# Creator
def cmdCreator():
    return OpenMayaMPx.asMPxPtr(motionTrace())


# Syntax creator
def syntaxCreator():
    syntax = OpenMaya.MSyntax()
    syntax.addFlag(kStartFlag, kStartLongFlag, OpenMaya.MSyntax.kLong)
    syntax.addFlag(kEndFlag, kEndLongFlag, OpenMaya.MSyntax.kLong)
    syntax.addFlag(kByFlag, kByLongFlag, OpenMaya.MSyntax.kLong)
    return syntax


# Initialize the script plug-in
def initializePlugin(mobject):
    mplugin = OpenMayaMPx.MFnPlugin(mobject, "Autodesk", "1.0", "Any")
    try:
        mplugin.registerCommand(kPluginCmdName, cmdCreator, syntaxCreator)
    except:
        sys.stderr.write("Failed to register command: %s\n" % kPluginCmdName)
        raise


# Uninitialize the script plug-in
def uninitializePlugin(mobject):
    mplugin = OpenMayaMPx.MFnPlugin(mobject)
    try:
        mplugin.deregisterCommand(kPluginCmdName)
    except:
        sys.stderr.write("Failed to unregister command: %s\n" % kPluginCmdName)
        raise