sweptEmitter/sweptEmitter.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:
// 
// Produces the dependency graph node "sweptEmitter".
//
// This node is an example of a particle emitter that emits in a direction
// from a curve or surface.
//
// The example MEL script "sweptEmitter.mel" shows how to create the node
// and appropriate connections to correctly establish a user defined particle emitter.
//

#include <maya/MIOStream.h>
#include <math.h>
#include <stdlib.h>

#include "sweptEmitter.h"

#include <maya/MDataHandle.h>
#include <maya/MFnDynSweptGeometryData.h>
#include <maya/MDynSweptLine.h>
#include <maya/MDynSweptTriangle.h>

#include <maya/MVectorArray.h>
#include <maya/MDoubleArray.h>
#include <maya/MIntArray.h>
#include <maya/MMatrix.h>
#include <maya/MArrayDataBuilder.h>

#include <maya/MFnDependencyNode.h>
#include <maya/MFnNumericAttribute.h>
#include <maya/MFnUnitAttribute.h>
#include <maya/MFnVectorArrayData.h>
#include <maya/MFnDoubleArrayData.h>
#include <maya/MFnArrayAttrsData.h>
#include <maya/MFnMatrixData.h>



MTypeId sweptEmitter::id( 0x80016 );


sweptEmitter::sweptEmitter()
:   lastWorldPoint(0, 0, 0, 1)
{
}


sweptEmitter::~sweptEmitter()
{
}


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


MStatus sweptEmitter::initialize()
//
//  Descriptions:
//      Initialize the node, create user defined attributes.
//
{
    return( MS::kSuccess );
}


MStatus sweptEmitter::compute(const MPlug& plug, MDataBlock& block)
//
//  Descriptions:
//      Call emit emit method to generate new particles.
//
{
    MStatus status;

    // Determine if we are requesting the output plug for this emitter node.
    //
    if( !(plug == mOutput) )
        return( MS::kUnknownParameter );

    // Get the logical index of the element this plug refers to,
    // because the node can be emitting particles into more 
    // than one particle shape.
    //
    int multiIndex = plug.logicalIndex( &status );
    McheckErr(status, "ERROR in plug.logicalIndex.\n");

    // Get output data arrays (position, velocity, or parentId)
    // that the particle shape is holding from the previous frame.
    //
    MArrayDataHandle hOutArray = block.outputArrayValue(mOutput, &status);
    McheckErr(status, "ERROR in hOutArray = block.outputArrayValue.\n");

    // Create a builder to aid in the array construction efficiently.
    //
    MArrayDataBuilder bOutArray = hOutArray.builder( &status );
    McheckErr(status, "ERROR in bOutArray = hOutArray.builder.\n");

    // Get the appropriate data array that is being currently evaluated.
    //
    MDataHandle hOut = bOutArray.addElement(multiIndex, &status);
    McheckErr(status, "ERROR in hOut = bOutArray.addElement.\n");

    // Get the data and apply the function set.
    //
    MFnArrayAttrsData fnOutput;
    MObject dOutput = fnOutput.create ( &status );
    McheckErr(status, "ERROR in fnOutput.create.\n");

    // Check if the particle object has reached it's maximum,
    // hence is full. If it is full then just return with zero particles.
    //
    bool beenFull = isFullValue( multiIndex, block );
    if( beenFull )
    {
        return( MS::kSuccess );
    }

    // Get deltaTime, currentTime and startTime.
    // If deltaTime <= 0.0, or currentTime <= startTime,
    // do not emit new pariticles and return.
    //
    MTime cT = currentTimeValue( block );
    MTime sT = startTimeValue( multiIndex, block );
    MTime dT = deltaTimeValue( multiIndex, block );
    if( (cT <= sT) || (dT <= 0.0) )
    {
        // We do not emit particles before the start time, 
        // and do not emit particles when moving backwards in time.
        // 

        // This code is necessary primarily the first time to 
        // establish the new data arrays allocated, and since we have 
        // already set the data array to length zero it does 
        // not generate any new particles.
        // 
        hOut.set( dOutput );
        block.setClean( plug );

        return( MS::kSuccess );
    }

    // Get speed, direction vector, and inheritFactor attributes.
    //
    double speed = speedValue( block );
    MVector dirV = directionVector( block );
    double inheritFactor = inheritFactorValue( multiIndex, block );

    // Get the position and velocity arrays to append new particle data.
    //
    MVectorArray fnOutPos = fnOutput.vectorArray("position", &status);
    MVectorArray fnOutVel = fnOutput.vectorArray("velocity", &status);

    // Convert deltaTime into seconds.
    //
    double dt = dT.as( MTime::kSeconds );
    
    // Apply rotation to the direction vector
    MVector rotatedV = useRotation ( dirV );


    // position,
    MVectorArray inPosAry;
    // velocity
    MVectorArray inVelAry;
    // emission rate
    MIntArray emitCountPP;


    // Get the swept geometry data
    //
    MObject thisObj = this->thisMObject();
    MPlug sweptPlug( thisObj, mSweptGeometry );

    if ( sweptPlug.isConnected() ) 
    {
        MDataHandle sweptHandle = block.inputValue( mSweptGeometry );
        // MObject sweptData = sweptHandle.asSweptGeometry();
        MObject sweptData = sweptHandle.data();
        MFnDynSweptGeometryData fnSweptData( sweptData );


        // Curve emission
        //
        if (fnSweptData.lineCount() > 0) {
            int numLines = fnSweptData.lineCount();
        
            for ( int i=0; i<numLines; i++ )
            {
                inPosAry.clear();
                inVelAry.clear();
                emitCountPP.clear();

                MDynSweptLine line = fnSweptData.sweptLine( i );

                // ... process current line ...
                MVector p1 = line.vertex( 0 );
                MVector p2 = line.vertex( 1 );

                inPosAry.append( p1 );
                inPosAry.append( p2 );

                inVelAry.append( MVector( 0,0,0 ) );
                inVelAry.append( MVector( 0,0,0 ) );

                // emit Rate for two points on line
                emitCountPP.clear();
                status = emitCountPerPoint( plug, block, 2, emitCountPP );

                emit( inPosAry, inVelAry, emitCountPP,
                    dt, speed, inheritFactor, rotatedV, fnOutPos, fnOutVel );

            }
        }

        // Surface emission (nurb or polygon)
        //
        if (fnSweptData.triangleCount() > 0) {
            int numTriangles = fnSweptData.triangleCount();
        
            for ( int i=0; i<numTriangles; i++ )
            {
                inPosAry.clear();
                inVelAry.clear();
                emitCountPP.clear();

                MDynSweptTriangle tri = fnSweptData.sweptTriangle( i );

                // ... process current triangle ...
                MVector p1 = tri.vertex( 0 );
                MVector p2 = tri.vertex( 1 );
                MVector p3 = tri.vertex( 2 );

                MVector center = p1 + p2 + p3;
                center /= 3.0;

                inPosAry.append( center );

                inVelAry.append( MVector( 0,0,0 ) );

                // emit Rate for two points on line
                emitCountPP.clear();
                status = emitCountPerPoint( plug, block, 1, emitCountPP );

                emit( inPosAry, inVelAry, emitCountPP,
                    dt, speed, inheritFactor, rotatedV, fnOutPos, fnOutVel );

            }
        }
    }

    // Update the data block with new dOutput and set plug clean.
    //
    hOut.set( dOutput );
    block.setClean( plug );

    return( MS::kSuccess );
}


void sweptEmitter::emit
    (
        const MVectorArray &inPosAry,   // points where new particles from
        const MVectorArray &inVelAry,   // initial velocity of new particles
        const MIntArray &emitCountPP,   // # of new particles per point
        double dt,                      // elapsed time
        double speed,                   // speed factor
        double inheritFactor,           // for inherit velocity
        MVector dirV,                   // emit direction
        MVectorArray &outPosAry,        // holding new particles position
        MVectorArray &outVelAry         // holding new particles velocity
    )
//
//  Descriptions:
//
{
    // check the length of input arrays.
    //
    int posLength = inPosAry.length();
    int velLength = inVelAry.length();
    int countLength = emitCountPP.length();
    if( (posLength != velLength) || (posLength != countLength) )
        return;

    // Compute total emit count.
    //
    int index;
    int totalCount = 0;
    for( index = 0; index < countLength; index ++ )
        totalCount += emitCountPP[index];

    if( totalCount <= 0 )
        return;

    // Map direction vector into world space and normalize it.
    //
    dirV.normalize();

    // Start emission.
    //
    int emitCount;
    MVector newPos, newVel;
    MVector prePos, sPos, sVel;
    for( index = 0; index < posLength; index++ )
    {
        emitCount = emitCountPP[index];
        if( emitCount <= 0 )
            continue;

        sPos = inPosAry[index];
        sVel = inVelAry[index];
        prePos = sPos - sVel * dt;

        for( int i = 0; i < emitCount; i++ )
        {
            double alpha = ( (double)i + drand48() ) / (double)emitCount;
            newPos = (1 - alpha) * prePos + alpha * sPos;
            newVel = dirV * speed;

            newPos += newVel * ( dt * (1 - alpha) );
            newVel += sVel * inheritFactor;

            // Add new data into output arrays.
            //
            outPosAry.append( newPos );
            outVelAry.append( newVel );
        }
    }

}

MVector sweptEmitter::useRotation ( MVector &direction )
{
    MStatus status;
    MVector rotatedVector;

    MObject thisNode = thisMObject();
    MFnDependencyNode fnThisNode( thisNode );

    // get worldMatrix attribute.
    //
    MObject worldMatrixAttr = fnThisNode.attribute( "worldMatrix" );

    // build worldMatrix plug, and specify which element the plug refers to.
    // We use the first element(the first dagPath of this emitter).
    //
    MPlug matrixPlug( thisNode, worldMatrixAttr );
    matrixPlug = matrixPlug.elementByLogicalIndex( 0 );

    // Get the value of the 'worldMatrix' attribute
    //
    MObject matrixObject;
    status = matrixPlug.getValue( matrixObject );
    if( !status )
    {
        status.perror("sweptEmitter::useRotation: get matrixObject");
        return ( direction );
    }

    MFnMatrixData worldMatrixData( matrixObject, &status );
    if( !status )
    {
        status.perror("sweptEmitter::useRotation: get worldMatrixData");
        return( direction );
    }

    MMatrix worldMatrix = worldMatrixData.matrix( &status );
    if( !status )
    {
        status.perror("sweptEmitter::useRotation: get worldMatrixData.matrix");
        return( direction );
    }

    rotatedVector = direction * worldMatrix;

    return( rotatedVector );
}



MStatus sweptEmitter::emitCountPerPoint
    (
        const MPlug &plug,
        MDataBlock &block,
        int length,                 // length of emitCountPP
        MIntArray &emitCountPP      // output: emitCount for each point
    )
//
//  Descriptions:
//      Compute emitCount for each point where new particles come from.
//
{
    MStatus status;

    int plugIndex = plug.logicalIndex( &status );
    McheckErr(status, "ERROR in emitCountPerPoint: when plug.logicalIndex.\n");

    // Get rate and delta time.
    //
    double rate = rateValue( block );
    MTime dt = deltaTimeValue( plugIndex, block );

    // Compute emitCount for each point.
    //
    double dblCount = rate * dt.as( MTime::kSeconds );

    int intCount = (int)dblCount;
    for( int i = 0; i < length; i++ )
    {
        emitCountPP.append( intCount );
    }

    return( MS::kSuccess );
}


MStatus initializePlugin(MObject obj)
{
    MStatus status;
    MFnPlugin plugin(obj, PLUGIN_COMPANY, "3.0", "Any");

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

    return status;
}

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

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

    return status;
}