scripted/helixCmd.py

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#   Creation Date:   2 October 2006

########################################################################
# DESCRIPTION:
#
# Produces the Python command "spHelix". 
#
# This script creates a NURBS curve in the shape of a helix.
# The command accepts these two arguments:
#
#   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