particleAttrNode/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 particleAttrNode : public MPxParticleAttributeMapperNode
{
public:
                        particleAttrNode();
                    ~particleAttrNode() override;

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

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

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:
};