dynExprField.h

//-
// ==========================================================================
// 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.
// ==========================================================================
//+

//  Description
//      The dynExprField node implements a uniform field, which allows 
//      the per particle attributes to drive the field's attributes.
//

#include <maya/MIOStream.h>
#include <maya/MVector.h>
#include <maya/MObject.h>
#include <maya/MPlug.h>
#include <maya/MDataBlock.h>
#include <maya/MFnPlugin.h>
#include <maya/MPxFieldNode.h>

#if defined(OSMac_MachO_)
#include <OpenGL/gl.h>
#else
#include <GL/gl.h>
#endif

#define McheckErr(stat, msg)            \
        if ( MS::kSuccess != stat )     \
        {                               \
                cerr << msg;            \
                return MS::kFailure;    \
        }

class dynExprField: public MPxFieldNode
{
public:
        dynExprField() {};
        virtual ~dynExprField() {};

        static void    *creator();
        static MStatus  initialize();

        // will compute output force.
        //
        virtual MStatus compute( const MPlug& plug, MDataBlock& block );

        virtual MStatus iconSizeAndOrigin(      GLuint& width,
                                                GLuint& height,
                                                GLuint& xbo,
                                                GLuint& ybo   );
        virtual MStatus iconBitmap(GLubyte* bitmap);

        //
        // attributes.
        //

        // direction of the force
        //
        static MObject  mDirection;

        // Other data members
        //
        static MTypeId  id;

private:

        // methods to get attribute value.
        //
        double  magnitude(MDataBlock& block);

        MVector direction(MDataBlock& block);

        // Compute the force to apply to each particle
        void apply(MDataBlock         &block,
                   int                 receptorSize,
                   const MDoubleArray &magnitudeArray,
                   const MDoubleArray &magnitudeOwnerArray,
                   const MVectorArray &directionArray,
                   const MVectorArray &directionOwnerArray,
                   MVectorArray       &outputForce);
};