polyTrgNode/polyTrgNode.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.
// ==========================================================================
//+

// DESCRIPTION:
//
// This plug-in demonstrates how to add user defined triangulation for meshes
// using the poly API class "MPxPolyTrg". 
//
// This node registers a user defined face triangulation function.
// After the function is registered, it can be used by any mesh in 
// the scene to do the triangulation (replace the mesh native 
// triangulation). In order for the mesh to use this function,
// an attribute on the mesh: "userTrg" has to be set to the name
// of the function. 
//  
// Different meshes may use different functions. Each of them 
// needs to be registered. The same node can provide more than 
// one function.  
//
// Example:
//  createNode polyTrgNode -n ptrg;
// 
//  polyPlane -w 1 -h 1 -sx 10 -sy 10 -ax 0 1 0 -tx 0 -ch 1 -n pp1;
//
//  select  -r pp1Shape;
//  setAttr pp1Shape.userTrg  -type "string" "triangulate";
//

#include <maya/MIOStream.h>

// API stuff.
#include <maya/MFnPlugin.h>

// Node stuff.
#include <maya/MPxPolyTrg.h>
#include <maya/MFnMessageAttribute.h>

// Command stuff.
#include <maya/MPxCommand.h>
#include <maya/MSyntax.h>
#include <maya/MArgDatabase.h>
#include <maya/MArgList.h>
#include <maya/MString.h>
#include <maya/MSelectionList.h>
#include <maya/MGlobal.h>
#include <maya/MDagPath.h>

//
// MACROS DECLARATION 
//

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

#define EQUAL(a,b) ( (((a-b) > -0.00001) && ((a-b) < 0.00001)) ? 1 : 0 )
#define EQUAL2(a,b) ((EQUAL(a[0],b[0]) && EQUAL(a[1],b[1]) ) ? 1 : 0)
#define EQUAL3(a,b) ((EQUAL(a[0],b[0]) && EQUAL(a[1],b[1]) && EQUAL(a[2],b[2]) ) ? 1 : 0)

#define MCHECKERR_RETURN(stat,msg)  \
    if ( MS::kSuccess != stat ) {   \
        displayError( msg );        \
        fErrorCount = 1;            \
        return MS::kFailure;        \
    }

#define MCHECKERR_BREAK(stat,msg)   \
    if ( MS::kSuccess != stat ) {   \
        displayError( msg );        \
        fErrorCount = 1;            \
        break;                      \
    }


//
// testPolyTrgNode node declaration
// 

class polyTrgNode : public MPxPolyTrg
{
public:
    polyTrgNode() {};
    ~polyTrgNode() override;

    MStatus     compute(const MPlug& plug, MDataBlock& data) override;
    void        postConstructor( ) override;
    bool        isAbstractClass( ) const override;

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

    // User triangulation - this is a triangulation per face.
    static  void        triangulateFace( const float    *vert, 
                                         const float    *norm, 
                                         const int      *loopSizes,
                                         const int      nbLoops,
                                         const int      nbTrg,
                                         unsigned short *trg );

public:
    static  MTypeId id;

private:
};

//
// polyTrgNode implementation
//

MTypeId polyTrgNode::id(0x101015);

polyTrgNode::~polyTrgNode() 
//
//  Description:
//      Destructor: unregister the triangulation function. 
//
{
    // Unregister the triangulation function.
    /* MStatus stat = */ unregisterTrgFunction( "triangulate" );
}

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

void polyTrgNode::postConstructor()
//
//  Description:
//      Constructor: register the triangulation function. 
//
{
    // Register the triangulation function.
    // The string given as a first parameter has to be
    // the same as the name given when setting the usrTrg
    // attribute on the mesh. See example above.
    // 
    /* MStatus stat = */ 
    registerTrgFunction( "triangulate", polyTrgNode::triangulateFace );
}

bool polyTrgNode::isAbstractClass( ) const
{
    return false;
}

MStatus polyTrgNode::initialize()
{
    return MS::kSuccess;
}

MStatus polyTrgNode::compute(const MPlug& plug, MDataBlock& data)
{
    return MS::kSuccess;
}

void 
polyTrgNode::triangulateFace( 
    const float     *vert,          // I: face vertex position
    const float     *norm,          // I: face normals per vertex
    const int       *loopSizes,     // I: number of vertices per loop 
    const int       nbLoops,        // I: number of loops in the face   
    const int       nbTrg,          // I: number of triangles to generate
    unsigned short *trg             // O: triangles - size = 3*nbTrg. 
                                    //    Note: this array is already allocated.
)
//
//  Description:
//      Triangulate a given face. Returns triangles given by 
//      the relative vertex ids. Example:
//          nbTrg = 2
//          trg: 0, 1, 2,  2, 3, 0
//
{
    // ======================================
    // Print the input.
    // ======================================
    cerr << "polyTrgNode::triangulate() - This is an API registered triangulation.\n";

    // Dump the data - this is a good example.
    cerr << "Numb Loops = " << nbLoops << "\n";
    int nbVert = 0;
    cerr << "Loop sizes: ";
    for (int i=0; i<nbLoops; i++ ) {
        nbVert += loopSizes[i];
        cerr << loopSizes[i] << " ";
    }
    cerr << "\n";
    cerr << "Numb Vert  = " << nbVert << "\n";

    cerr << "Vertices:\n";
    for (int v=0; v<nbVert; v++ ) {
        cerr << vert[3*v] << " " << vert[3*v+1] << " " << vert[3*v+2] << " " <<"\n";
    }

    // Now triangulate.
    // ======================================
    
    cerr << " nbTrg = " << nbTrg << "\n";

    // ======================================
    // Generate a triangulation for this face.
    // ======================================
    unsigned short v0 = 0;
    unsigned short v1 = 1;
    unsigned short v2 = 2;
    for (int k=0; k<nbTrg; k++){
        trg[3*k]    = v0;
        trg[3*k+1]  = v1;
        trg[3*k+2]  = v2;

        v1 = v2;
        v2 ++;
        if (v2 >= nbVert) {
            v2 = 0;
        }
    }
    // ======================================


    // ======================================
    // Print the result.
    // ======================================
    cerr << "Triangulation\n";
    for (int k1=0; k1<nbTrg; k1++){
        cerr << trg[3*k1] << " " << trg[3*k1+1] << " " << trg[3*k1+2] << "\n";
    }
    // ======================================
}




//
// Node and command registration
//

MStatus initializePlugin(MObject obj)
{
    MFnPlugin plugin(obj, "MPxPlyTrg::Poly api example plug-in", "4.5", "Any");

    MStatus stat = plugin.registerNode("polyTrgNode",
                                        polyTrgNode::id,
                                        polyTrgNode::creator,
                                        polyTrgNode::initialize);
    return stat;
}

MStatus uninitializePlugin(MObject obj)
{
    MFnPlugin plugin(obj);
    MStatus stat = plugin.deregisterNode(polyTrgNode::id);
    return stat;
}