particleAttrNode.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.
// ==========================================================================
//+

//
//      Class:  particleAttrNode
//
//      Author: Lonnie Li
//
//      Description:
//
//              particleAttrNode is an example node that extends the MPxParticleAttributeMapperNode
//      type. These nodes allow us to define custom nodes to map per-particle attribute data
//      to a particle shape.
//
//              In this particular example, we have defined two operations:
//
//              - compute2DTexture()
//              - computeMesh()
//
//              compute2DTexture() replicates the internal behaviour of Maya's internal 'arrayMapper'
//      node at the API level. Given an input texture node and a U/V coord per particle input,
//      this node will evaluate the texture at the given coordinates and map the result back
//      to the outColorPP or outValuePP attributes. See the method description for compute2DTexture()
//      for details on how to setup a proper attribute mapping graph.
//
//              computeMesh() is a user-defined behaviour. It is called when the 'computeNode' attribute
//      is connected to a polygonal mesh. From there, given a particle count, it will map the
//      object space vertex positions of the mesh to a user-defined 'outPositions' vector attribute.
//      This 'outPositions' attribute can then be connected to a vector typed, per-particle attribute
//      on the shape to drive. In our particular example we drive the particle shape's 'rampPosition'
//      attribute. For further details, see the method description for computeMesh() to setup
//      this example.
//

#include <maya/MPxParticleAttributeMapperNode.h>
#include <maya/MTypeId.h>

class MPlug;
class MDataBlock;

class particleAttrNode : public MPxParticleAttributeMapperNode
{
public:
                                                particleAttrNode();
        virtual                         ~particleAttrNode();

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

        virtual MStatus         compute( const MPlug& plug, MDataBlock& block );

protected:
        MStatus                         compute2DTexture( const MPlug& plug, MDataBlock& block );
        MStatus                         computeMesh( const MPlug& plug, MDataBlock& block );

public:
        static  MTypeId         id;
        static  MObject         outPositionPP;
        static  MObject         particleCount;

private:
};