arcLenNode.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 <string.h>
#include <maya/MIOStream.h>
#include <math.h>

#include <maya/MPxNode.h>
#include <maya/MFnNumericAttribute.h>
#include <maya/MFnTypedAttribute.h>
#include <maya/MFnPlugin.h>
#include <maya/MFnNurbsCurve.h>
#include <maya/MString.h> 
#include <maya/MTypeId.h> 
#include <maya/MPlug.h> 
#include <maya/MDataBlock.h>
#include <maya/MDataHandle.h> 

class arcLen : public MPxNode
{
public:
                                                arcLen();
        virtual                         ~arcLen(); 

    virtual MStatus             compute( const MPlug& plug, MDataBlock& data );
        static  void*           creator();
        static  MStatus         initialize();

public:
        static  MObject     inputCurve;  // The input curve.
        static  MObject     output;      // The output value.
        static  MTypeId         id;          // The IFF type id
};

MTypeId     arcLen::id( 0x80001  );
MObject     arcLen::inputCurve;        
MObject     arcLen::output;       

arcLen::arcLen() {}
arcLen::~arcLen() {}

void* arcLen::creator()
{
        return new arcLen();
}

MStatus arcLen::compute( const MPlug& plug, MDataBlock& data )
{
        
        MStatus status;
 
        if( plug == output )
        {
                MDataHandle inputData = data.inputValue( inputCurve, &status );

                if( !status ) {
                        status.perror("ERROR getting data");
                } else {
                        MObject curve = inputData.asNurbsCurveTransformed();
                        MFnNurbsCurve curveFn( curve, &status ); 
                        if( !status ) {
                                status.perror("ERROR creating curve function set");
                        } else {
                                double result = curveFn.length();
                                MDataHandle outputHandle = data.outputValue( arcLen::output );
                                outputHandle.set( result );
                                data.setClean(plug);
                        }
                }
        } else {
                return MS::kUnknownParameter;
        }

        return MS::kSuccess;
}

MStatus arcLen::initialize()
{
        MFnNumericAttribute numericAttr;
        MFnTypedAttribute   typedAttr;
        MStatus status;

        inputCurve = typedAttr.create( "inputCurve", "in", 
                                                                        MFnData::kNurbsCurve, 
                                                                        &status );

        if( !status ) {
                status.perror("ERROR creating arcLen curve attribute");
                return status;
        }

        output = numericAttr.create( "output", "out", 
                                                                        MFnNumericData::kDouble, 0.0, 
                                                                        &status );
        if( !status ) {
                status.perror("ERROR creating arcLen output attribute");
                return status;
        }
        numericAttr.setWritable(false);

        status = addAttribute( inputCurve );
        if( !status ) {
                status.perror("addAttribute(inputCurve)");
                return status;
        }

        status = addAttribute( output );
        if( !status ) {
                status.perror("addAttribute(output)");
                return status;
        }

        status = attributeAffects( inputCurve, output );
        if( !status ) {
                status.perror("attributeAffects(inputCurve, output)");
                return status;
        }

        return MS::kSuccess;
}

MStatus initializePlugin( MObject obj )
{
        MStatus   status;
        MFnPlugin plugin( obj, PLUGIN_COMPANY, "3.0", "Any");

        status = plugin.registerNode( "arcLen", arcLen::id, arcLen::creator,
                                                                                           arcLen::initialize);
        if (!status) {
                status.perror("registerNode");
                return status;
        }

        return status;
}

MStatus uninitializePlugin( MObject obj)
{
        MStatus   status;
        MFnPlugin plugin( obj );

        status = plugin.deregisterNode( arcLen::id );
        if (!status) {
                status.perror("deregisterNode");
                return status;
        }

        return status;
}