sweptEmitter/sweptEmitter.cpp
 
 
 
sweptEmitter/sweptEmitter.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.
// ==========================================================================
//+

#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/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;
}