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# helixCmd.py

    #-
    # ==========================================================================
    # Copyright (C) 1995 - 2006 Autodesk, Inc. and/or its licensors.  All
    # rights reserved.
    #
    # The coded instructions, statements, computer programs, and/or related
    # material (collectively the "Data") in these files contain unpublished
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    # licensors, which is protected by U.S. and Canadian federal copyright
    # law and by international treaties.
    #
    # The Data is provided for use exclusively by You. You have the right
    # to use, modify, and incorporate this Data into other products for
    # purposes authorized by the Autodesk software license agreement,
    # without fee.
    #
    # The copyright notices in the Software and this entire statement,
    # including the above license grant, this restriction and the
    # following disclaimer, must be included in all copies of the
    # Software, in whole or in part, and all derivative works of
    # the Software, unless such copies or derivative works are solely
    # in the form of machine-executable object code generated by a
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    #
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    #+

    #
    #   Creation Date:   2 October 2006
    #
    #   Description:
    #
    #       Creates a NURBS curve in the shape of a helix
    #
    #   Options:
    #
    #       p=#     The pitch of the helix, default to 0.5
    #       r=#     The radius of the helix, default to 4.0
    #
    #   Example:
    #
    #       From Python:
    #           import maya
    #           maya.cmds.spHelix(p=0.3, r=7)
    #
    #       From Mel:
    #           spHelix -p 0.3 -r 7
    #

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

    kPluginCmdName="spHelix"

    kPitchFlag = "-p"
    kPitchLongFlag = "-pitch"
    kRadiusFlag = "-r"
    kRadiusLongFlag = "-radius"

    # command
    class scriptedCommand(OpenMayaMPx.MPxCommand):
        def __init__(self):
            OpenMayaMPx.MPxCommand.__init__(self)

        def doIt(self, args):
            deg = 3
            ncvs = 20
            spans = ncvs - deg
            nknots = spans+2*deg-1
            radius = 4.0
            pitch = 0.5

            # Parse the arguments.
            argData = OpenMaya.MArgDatabase(self.syntax(), args)
            if argData.isFlagSet(kPitchFlag):
                pitch = argData.flagArgumentDouble(kPitchFlag, 0)
            if argData.isFlagSet(kRadiusFlag):
                radius = argData.flagArgumentDouble(kRadiusFlag, 0)

            controlVertices = OpenMaya.MPointArray()
            knotSequences = OpenMaya.MDoubleArray()

            # Set up cvs and knots for the helix
            #
            for i in range(0, ncvs):
                controlVertices.append( OpenMaya.MPoint( radius * math.cos(i),
                    pitch * i, radius * math.sin(i) ) )

            for i in range(0, nknots):
                knotSequences.append( i )

            # Now create the curve
            #
            curveFn = OpenMaya.MFnNurbsCurve()

            nullObj = OpenMaya.MObject()

            try:
                # This plugin normally creates the curve by passing in the
                # cv's.  A function to create curves by passing in the ep's
                # has been added.  Set this to False to get that behaviour.
                #
                if True:
                    curveFn.create( controlVertices,
                                    knotSequences, deg,
                                    OpenMaya.MFnNurbsCurve.kOpen,
                                    0, 0,
                                    nullObj )
                else:
                    curveFn.createWithEditPoints(controlVertices,
                                    3, OpenMaya.MFnNurbsCurve.kOpen,
                                    False, False, False)
            except:
                sys.stderr.write( "Error creating curve.\n" )
                raise

    # Creator
    def cmdCreator():
        # Create the command
        return OpenMayaMPx.asMPxPtr( scriptedCommand() )

    # Syntax creator
    def syntaxCreator():
        syntax = OpenMaya.MSyntax()
        syntax.addFlag(kPitchFlag, kPitchLongFlag, OpenMaya.MSyntax.kDouble)
        syntax.addFlag(kRadiusFlag, kRadiusLongFlag, OpenMaya.MSyntax.kDouble)
        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