helixCmd.py

#-
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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