animCubeNode/animCubeNode.cpp

//-
// ==========================================================================
// Copyright 2015 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 produces the dependency graph node "animCube".
// 
// It demonstrates how to take time as an input, and create polygonal geometry for output.
// The compute method of the node constructs a polygonal cube whose size depends on the current frame number.
// The resulting mesh is passed to an internal Maya node, which displays it and allows it to be positioned.
// 
// To use this node, execute the MEL command "animCubeNode.mel" that contains the following commands:
//
// createNode transform -n animCube1;
// createNode mesh -n animCubeShape1 -p animCube1;
// createNode animCube -n animCubeNode1;
// connectAttr time1.outTime animCubeNode1.time;
// connectAttr animCubeNode1.outputMesh animCubeShape1.inMesh;
// 
// This creates a mesh node under a transform node that is hooked into the world for display.
// It then creates an animCube node and connects its input to the time node, and its output to the mesh node.
// Now, a cube appears on the screen.
// 
// If the play button on the time slider is pressed, the displayed cube will grow and shrink as the frame number changes.
// 

#include <maya/MTime.h>
#include <maya/MFnMesh.h>
#include <maya/MPoint.h>
#include <maya/MFloatPoint.h>
#include <maya/MFloatPointArray.h>
#include <maya/MIntArray.h>
#include <maya/MDoubleArray.h>
#include <maya/MFnUnitAttribute.h>
#include <maya/MFnTypedAttribute.h>
#include <maya/MFnPlugin.h>

#include <maya/MPxNode.h>
#include <maya/MObject.h>
#include <maya/MPlug.h>
#include <maya/MDataBlock.h>
#include <maya/MFnMeshData.h>

#include <maya/MIOStream.h>

MStatus returnStatus;

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

class animCube : public MPxNode
{
public:
                    animCube() {};
            ~animCube() override {};
    MStatus compute(const MPlug& plug, MDataBlock& data) override;
    static  void*   creator();
    static  MStatus initialize();

    static MObject  time;
    static MObject  outputMesh;
    static MTypeId  id;

protected:
    MObject createMesh(const MTime& time, MObject& outData, MStatus& stat);

    // Helpers
    MObject createQuads(const MFloatPointArray& points, MObject& outData, MStatus& stat);
    MObject createReverseQuads(const MFloatPointArray& points, MObject& outData, MStatus& stat);
    MObject createTris(const MFloatPointArray& points, MObject& outData, MStatus& stat);
    MObject createReverseTris(const MFloatPointArray& points, MObject& outData, MStatus& stat);
};

MObject animCube::time;
MObject animCube::outputMesh;
MTypeId animCube::id( 0x80000 );

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

MStatus animCube::initialize()
{
    MFnUnitAttribute unitAttr;
    MFnTypedAttribute typedAttr;

    MStatus returnStatus;

    animCube::time = unitAttr.create( "time", "tm",
                                          MFnUnitAttribute::kTime,
                                          0.0, &returnStatus );
    McheckErr(returnStatus, "ERROR creating animCube time attribute\n");


    animCube::outputMesh = typedAttr.create( "outputMesh", "out",
                                                 MFnData::kMesh,
                                                 MObject::kNullObj,
                                                 &returnStatus ); 
    McheckErr(returnStatus, "ERROR creating animCube output attribute\n");
    typedAttr.setStorable(false);

    returnStatus = addAttribute(animCube::time);
    McheckErr(returnStatus, "ERROR adding time attribute\n");

    returnStatus = addAttribute(animCube::outputMesh);
    McheckErr(returnStatus, "ERROR adding outputMesh attribute\n");

    returnStatus = attributeAffects(animCube::time,
                                    animCube::outputMesh);
    McheckErr(returnStatus, "ERROR in attributeAffects\n");

    return MS::kSuccess;
}

MObject animCube::createMesh(const MTime& time,
                              MObject& outData,
                              MStatus& stat)

{
    // Scale the cube on the frame number, wrap every 10 frames.
    //
    const int frame = (int)time.as( MTime::kFilm );
    const float cubeSize = 0.5f * (float)( frame % 10 + 1 );

    MFloatPointArray points;
    points.append( -cubeSize, -cubeSize, -cubeSize );
    points.append(  cubeSize, -cubeSize, -cubeSize );
    points.append(  cubeSize, -cubeSize,  cubeSize );
    points.append( -cubeSize, -cubeSize,  cubeSize );
    points.append( -cubeSize,  cubeSize, -cubeSize );
    points.append( -cubeSize,  cubeSize,  cubeSize );
    points.append(  cubeSize,  cubeSize,  cubeSize );
    points.append(  cubeSize,  cubeSize, -cubeSize );

    MObject newMesh;

    static const bool sTestVertexIdAndFaceId =
        (getenv("MAYA_TEST_VERTEXID_AND_FACEID") != NULL);
    if (sTestVertexIdAndFaceId)
    {
        // If the env var is set, the topology of the cube will be changed over
        // frame number (looping in every 4 frames). When the shape is assigned
        // with a hwPhongShader, the shader receives vertex ids and face ids,
        // which are generated from polygonConnects passed to MFnMesh::create
        // method in this plugin.
        //
        switch (frame % 4)
        {
        case 1:
            newMesh = createQuads(points, outData, stat);
            break;
        case 2:
            newMesh = createReverseQuads(points, outData, stat);
            break;
        case 3:
            newMesh = createTris(points, outData, stat);
            break;
        case 0:
            newMesh = createReverseTris(points, outData, stat);
            break;
        default:
            newMesh = createQuads(points, outData, stat);
            break;
        }
    }
    else
    {
        newMesh = createQuads(points, outData, stat);
    }

    return newMesh;
}

MObject animCube::createQuads(
    const MFloatPointArray& points,
    MObject& outData,
    MStatus& stat)
{
    // Set up an array containing the number of vertices
    // for each of the 6 cube faces (4 vertices per face)
    //
    const int numFaces = 6;
    int face_counts[numFaces] = { 4, 4, 4, 4, 4, 4 };
    MIntArray faceCounts( face_counts, numFaces );

    // Set up and array to assign vertices from points to each face 
    //
    const int numFaceConnects = 24;
    int face_connects[ numFaceConnects ] = {0, 1, 2, 3,
                                            4, 5, 6, 7,
                                            3, 2, 6, 5,
                                            0, 3, 5, 4,
                                            0, 4, 7, 1,
                                            1, 7, 6, 2};
    MIntArray faceConnects( face_connects, numFaceConnects );
    
    MFnMesh meshFS;
    return meshFS.create(points.length(), faceCounts.length(),
        points, faceCounts, faceConnects, outData, &stat);
}

MObject animCube::createReverseQuads(
    const MFloatPointArray& points,
    MObject& outData,
    MStatus& stat)
{
    // Set up an array containing the number of vertices
    // for each of the 6 cube faces (4 vertices per face)
    //
    const int numFaces = 6;
    int face_counts[numFaces] = { 4, 4, 4, 4, 4, 4 };
    MIntArray faceCounts( face_counts, numFaces );

    // Set up and array to assign vertices from points to each face
    //
    const int numFaceConnects = 24;
    int face_connects[ numFaceConnects ] = {0, 3, 2, 1,
                                            4, 7, 6, 5,
                                            3, 5, 6, 2,
                                            0, 4, 5, 3,
                                            0, 1, 7, 4,
                                            1, 2, 6, 7};
    MIntArray faceConnects( face_connects, numFaceConnects );

    MFnMesh meshFS;
    return meshFS.create(points.length(), faceCounts.length(),
        points, faceCounts, faceConnects, outData, &stat);
}

MObject animCube::createTris(
    const MFloatPointArray& points,
    MObject& outData,
    MStatus& stat)
{
    // Set up an array containing the number of vertices
    // for each of the 12 triangles (3 verticies per triangle)
    //
    const int numFaces = 12;
    int face_counts[numFaces] = { 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3};
    MIntArray faceCounts( face_counts, numFaces );

    // Set up and array to assign vertices from points to each face
    //
    const int numFaceConnects = 36;
    int face_connects[ numFaceConnects ] = {0, 1, 2,
                                            2, 3, 0,
                                            4, 5, 6,
                                            6, 7, 4,
                                            3, 2, 6,
                                            6, 5, 3,
                                            0, 3, 5,
                                            5, 4, 0,
                                            0, 4, 7,
                                            7, 1, 0,
                                            1, 7, 6,
                                            6, 2, 1};
    MIntArray faceConnects( face_connects, numFaceConnects );

    MFnMesh meshFS;
    return meshFS.create(points.length(), faceCounts.length(),
        points, faceCounts, faceConnects, outData, &stat);
}

MObject animCube::createReverseTris(
    const MFloatPointArray& points,
    MObject& outData,
    MStatus& stat)
{
    // Set up an array containing the number of vertices
    // for each of the 12 triangles (3 verticies per triangle)
    //
    const int numFaces = 12;
    int face_counts[numFaces] = { 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3};
    MIntArray faceCounts( face_counts, numFaces );

    // Set up and array to assign vertices from points to each face
    //
    const int numFaceConnects = 36;
    int face_connects[ numFaceConnects ] = {0, 2, 1,
                                            2, 0, 3,
                                            4, 6, 5,
                                            6, 4, 7,
                                            3, 6, 2,
                                            6, 3, 5,
                                            0, 5, 3,
                                            5, 0, 4,
                                            0, 7, 4,
                                            7, 0, 1,
                                            1, 6, 7,
                                            6, 1, 2};
    MIntArray faceConnects( face_connects, numFaceConnects );

    MFnMesh meshFS;
    return meshFS.create(points.length(), faceCounts.length(),
        points, faceCounts, faceConnects, outData, &stat);
}

MStatus animCube::compute(const MPlug& plug, MDataBlock& data)

{
    MStatus returnStatus;

    if (plug == outputMesh) {
        /* Get time */
        MDataHandle timeData = data.inputValue( time, &returnStatus ); 
        McheckErr(returnStatus, "Error getting time data handle\n");
        MTime time = timeData.asTime();

        /* Get output object */

        MDataHandle outputHandle = data.outputValue(outputMesh, &returnStatus);
        McheckErr(returnStatus, "ERROR getting polygon data handle\n");

        MFnMeshData dataCreator;
        MObject newOutputData = dataCreator.create(&returnStatus);
        McheckErr(returnStatus, "ERROR creating outputData");

        createMesh(time, newOutputData, returnStatus);
        McheckErr(returnStatus, "ERROR creating new Cube");

        outputHandle.set(newOutputData);
        data.setClean( plug );
    } else
        return MS::kUnknownParameter;

    return MS::kSuccess;
}

MStatus initializePlugin(MObject obj)
{
    MStatus   status;
    MFnPlugin plugin(obj, PLUGIN_COMPANY, "4.0", "Any");

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

    return status;
}

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

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

    return status;
}