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# helixCmd.cpp

    //-
    // ==========================================================================
    // Copyright 1995,2006,2008 Autodesk, Inc. All rights reserved.
    //
    // Use of this software is subject to the terms of the Autodesk
    // license agreement provided at the time of installation or download,
    // or which otherwise accompanies this software in either electronic
    // or hard copy form.
    // ==========================================================================
    //+

    #include <math.h>

    #include <maya/MIOStream.h>
    #include <maya/MSimple.h>
    #include <maya/MFnNurbsCurve.h>
    #include <maya/MPointArray.h>
    #include <maya/MDoubleArray.h>
    #include <maya/MPoint.h>

    DeclareSimpleCommand( helix, PLUGIN_COMPANY, "3.0");

    MStatus helix::doIt( const MArgList& args )
    {
        MStatus stat;

        const unsigned  deg     = 3;            // Curve Degree
        const unsigned  ncvs    = 20;           // Number of CVs
        const unsigned  spans   = ncvs - deg;   // Number of spans
        const unsigned  nknots  = spans+2*deg-1;// Number of knots
        double  radius          = 4.0;          // Helix radius
        double  pitch           = 0.5;          // Helix pitch
        unsigned    i;

        // Parse the arguments.
        for ( i = 0; i < args.length(); i++ )
            if ( MString( "-p" ) == args.asString( i, &stat )
                    && MS::kSuccess == stat)
            {
                double tmp = args.asDouble( ++i, &stat );
                if ( MS::kSuccess == stat )
                    pitch = tmp;
            }
            else if ( MString( "-r" ) == args.asString( i, &stat )
                    && MS::kSuccess == stat)
            {
                double tmp = args.asDouble( ++i, &stat );
                if ( MS::kSuccess == stat )
                    radius = tmp;
            }

        MPointArray  controlVertices;
        MDoubleArray knotSequences;

        // Set up cvs and knots for the helix
        //
        for (i = 0; i < ncvs; i++)
            controlVertices.append( MPoint( radius * cos( (double)i ),
                pitch * (double)i, radius * sin( (double)i ) ) );

        for (i = 0; i < nknots; i++)
            knotSequences.append( (double)i );

        // Now create the curve
        //
        MFnNurbsCurve curveFn;

        curveFn.create( controlVertices,
                        knotSequences, deg,
                        MFnNurbsCurve::kOpen,
                        false, false,
                        MObject::kNullObj,
                        &stat );

        if ( MS::kSuccess != stat )
            cout<<"Error creating curve."<<endl;

        return stat;
    }