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# dynExprField.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 <math.h>

    #include <dynExprField.h>

    #include <maya/MIOStream.h>
    #include <maya/MTime.h>
    #include <maya/MFloatVector.h>
    #include <maya/MVectorArray.h>
    #include <maya/MDoubleArray.h>
    #include <maya/MString.h>
    #include <maya/MMatrix.h>

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

    MObject dynExprField::mDirection;

    MTypeId dynExprField::id( 0x00107340 );

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

    MStatus dynExprField::initialize()
    //
    //  Descriptions:
    //      Initialize the node, attributes.
    //
    {
        MStatus status;
        MFnNumericAttribute numAttr;

        // create the field basic attributes.
        //
        mDirection = numAttr.createPoint("direction","dir");
        numAttr.setDefault( 0.0, 1.0, 0.0 );
        numAttr.setKeyable(true);
        numAttr.setStorable(true);
        numAttr.setReadable(true);
        numAttr.setWritable(true);
        status = addAttribute( mDirection );
        attributeAffects(mDirection, mOutputForce);

        return( MS::kSuccess );
    }

    MStatus dynExprField::compute(const MPlug& plug, MDataBlock& block)
    //
    //  Descriptions:
    //      compute output force.
    //
    {
        MStatus status;

        if( !(plug == mOutputForce) )
            return( MS::kUnknownParameter );

        // get the logical index of the element this plug refers to.
        //
        int multiIndex = plug.logicalIndex( &status );
        McheckErr(status, "ERROR in plug.logicalIndex.\n");

        // Get input data handle, use outputArrayValue since we do not
        // want to evaluate both inputs, only the one related to the
        // requested multiIndex. Evaluating both inputs at once would cause
        // a dependency graph loop.

        MArrayDataHandle hInputArray = block.outputArrayValue( mInputData, &status );
        McheckErr(status,"ERROR in hInputArray = block.outputArrayValue().\n");

        status = hInputArray.jumpToElement( multiIndex );
        McheckErr(status, "ERROR: hInputArray.jumpToElement failed.\n");

        // get children of aInputData.

        MDataHandle hCompond = hInputArray.inputValue( &status );
        McheckErr(status, "ERROR in hCompond=hInputArray.inputValue\n");

        MDataHandle hPosition = hCompond.child( mInputPositions );
        MObject dPosition = hPosition.data();
        MFnVectorArrayData fnPosition( dPosition );
        MVectorArray points = fnPosition.array( &status );
        McheckErr(status, "ERROR in fnPosition.array(), not find points.\n");

        // Comment out the following since velocity, and mass are
        // not needed in this field.
        //
        // MDataHandle hVelocity = hCompond.child( mInputVelocities );
        // MObject dVelocity = hVelocity.data();
        // MFnVectorArrayData fnVelocity( dVelocity );
        // MVectorArray velocities = fnVelocity.array( &status );
        // McheckErr(status, "ERROR in fnVelocity.array(), not find velocities.\n");
        //
        // MDataHandle hMass = hCompond.child( mInputMass );
        // MObject dMass = hMass.data();
        // MFnDoubleArrayData fnMass( dMass );
        // MDoubleArray masses = fnMass.array( &status );
        // McheckErr(status, "ERROR in fnMass.array(), not find masses.\n");

        // The attribute mInputPPData contains the attribute in an array form
        // parpared by the particleShape if the particleShape has per particle
        // attribute fieldName_attrName.
        //
        // Suppose a field with the name dynExprField1 is connecting to
        // particleShape1, and the particleShape1 has per particle float attribute
        // dynExprField1_magnitude and vector attribute dynExprField1_direction,
        // then hInputPPArray will contains a MdoubleArray with the corresponding
        // name "magnitude" and a MvectorArray with the name "direction".  This
        // is a mechanism to allow the field attributes being driven by dynamic
        // expression.
        MArrayDataHandle mhInputPPData = block.inputArrayValue( mInputPPData, &status );
        McheckErr(status,"ERROR in mhInputPPData = block.inputArrayValue().\n");

        status = mhInputPPData.jumpToElement( multiIndex );
        McheckErr(status, "ERROR: mhInputPPArray.jumpToElement failed.\n");

        MDataHandle hInputPPData = mhInputPPData.inputValue( &status );
        McheckErr(status, "ERROR in hInputPPData = mhInputPPData.inputValue\n");

        MObject dInputPPData = hInputPPData.data();
        MFnArrayAttrsData inputPPArray( dInputPPData );

        MDataHandle hOwnerPPData = block.inputValue( mOwnerPPData, &status );
        McheckErr(status, "ERROR in hOwnerPPData = block.inputValue\n");

        MObject dOwnerPPData = hOwnerPPData.data();
        MFnArrayAttrsData ownerPPArray( dOwnerPPData );

        const MString magString("magnitude");
        MFnArrayAttrsData::Type doubleType(MFnArrayAttrsData::kDoubleArray);

        bool arrayExist;
        MDoubleArray magnitudeArray;
        arrayExist = inputPPArray.checkArrayExist(magString, doubleType, &status);
        // McheckErr(status, "ERROR in checkArrayExist(magnitude)\n");
        if(arrayExist) {
            magnitudeArray = inputPPArray.getDoubleData(magString, &status);
            // McheckErr(status, "ERROR in inputPPArray.doubleArray(magnitude)\n");
        }

        MDoubleArray magnitudeOwnerArray;
        arrayExist = ownerPPArray.checkArrayExist(magString, doubleType, &status);
        // McheckErr(status, "ERROR in checkArrayExist(magnitude)\n");
        if(arrayExist) {
            magnitudeOwnerArray = ownerPPArray.getDoubleData(magString, &status);
            // McheckErr(status, "ERROR in ownerPPArray.doubleArray(magnitude)\n");
        }

        const MString dirString("direction");
        MFnArrayAttrsData::Type vectorType(MFnArrayAttrsData::kVectorArray);

        arrayExist = inputPPArray.checkArrayExist(dirString, vectorType, &status);
            MVectorArray directionArray;
        // McheckErr(status, "ERROR in checkArrayExist(direction)\n");
        if(arrayExist) {
            directionArray = inputPPArray.getVectorData(dirString, &status);
            // McheckErr(status, "ERROR in inputPPArray.vectorArray(direction)\n");
        }

        arrayExist = ownerPPArray.checkArrayExist(dirString, vectorType, &status);
            MVectorArray directionOwnerArray;
        // McheckErr(status, "ERROR in checkArrayExist(direction)\n");
        if(arrayExist) {
            directionOwnerArray = ownerPPArray.getVectorData(dirString, &status);
            // McheckErr(status, "ERROR in ownerPPArray.vectorArray(direction)\n");
        }

        // Compute the output force.
        //
        MVectorArray forceArray;

        apply( block, points.length(), magnitudeArray, magnitudeOwnerArray,
               directionArray, directionOwnerArray, forceArray );

        // get output data handle
        //
        MArrayDataHandle hOutArray = block.outputArrayValue( mOutputForce, &status);
        McheckErr(status, "ERROR in hOutArray = block.outputArrayValue.\n");
        MArrayDataBuilder bOutArray = hOutArray.builder( &status );
        McheckErr(status, "ERROR in bOutArray = hOutArray.builder.\n");

        // get output force array from block.
        //
        MDataHandle hOut = bOutArray.addElement(multiIndex, &status);
        McheckErr(status, "ERROR in hOut = bOutArray.addElement.\n");

        MFnVectorArrayData fnOutputForce;
        MObject dOutputForce = fnOutputForce.create( forceArray, &status );
        McheckErr(status, "ERROR in dOutputForce = fnOutputForce.create\n");

        // update data block with new output force data.
        //
        hOut.set( dOutputForce );
        block.setClean( plug );

        return( MS::kSuccess );
    }

    MStatus dynExprField::iconSizeAndOrigin(GLuint& width,
                        GLuint& height,
                        GLuint& xbo,
                        GLuint& ybo   )
    //
    //  This method is not required to be overridden.  It should be overridden
    //  if the plug-in has custom icon.
    //
    //  The width and height have to be a multiple of 32 on Windows and 16 on
    //  other platform.
    //
    //  Define an 8x8 icon at the lower left corner of the 32x32 grid.
    //  (xbo, ybo) of (4,4) makes sure the icon is center at origin.
    //
    {
        width = 32;
        height = 32;
        xbo = 4;
        ybo = 4;
        return MS::kSuccess;
    }

    MStatus dynExprField::iconBitmap(GLubyte* bitmap)
    //
    //  This method is not required to be overridden.  It should be overridden
    //  if the plug-in has custom icon.
    //
    //  Define an 8x8 icon at the lower left corner of the 32x32 grid.
    //  (xbo, ybo) of (4,4) makes sure the icon is center at origin.
    {
        bitmap[0]  = 0x18;
        bitmap[4]  = 0x18;
        bitmap[8]  = 0x18;
        bitmap[12] = 0x18;
        bitmap[16] = 0x18;
        bitmap[20] = 0x5A;
        bitmap[24] = 0x3C;
        bitmap[28] = 0x18;

        return MS::kSuccess;
    }

    MStatus initializePlugin(MObject obj)
    {
        MStatus status;
        MFnPlugin plugin(obj, PLUGIN_COMPANY, "6.0", "Any");

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

        return status;
    }

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

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

        return status;
    }

    double dynExprField::magnitude( MDataBlock& block )
    {
        MStatus status;
        MDataHandle hValue = block.inputValue( mMagnitude, &status );

        double value = 0.0;
        if( status == MS::kSuccess )
            value = hValue.asDouble();

        return( value );
    }

    MVector dynExprField::direction( MDataBlock& block )
    {
        MFloatVector &fV = block.inputValue(mDirection).asFloatVector();
        return( MVector(fV.x, fV.y, fV.z) );
    }

    void dynExprField::apply(
    MDataBlock         &block,
    int                 receptorSize,
    const MDoubleArray &magnitudeArray,
    const MDoubleArray &magnitudeOwnerArray,
    const MVectorArray &directionArray,
    const MVectorArray &directionOwnerArray,
    MVectorArray       &outputForce
    )
    //
    //      Compute output force for each particle.  If there exists the
    //      corresponding per particle attribute, use the data passed from
    //      particle shape (stored in magnitudeArray and directionArray).
    //      Otherwise, use the attribute value from the field.
    //
    {
            // get the default values
        MVector defaultDir = direction(block);
        double  defaultMag = magnitude(block);
        int magArraySize = magnitudeArray.length();
        int dirArraySize = directionArray.length();
        int magOwnerArraySize = magnitudeOwnerArray.length();
        int dirOwnerArraySize = directionOwnerArray.length();
        int numOfOwner = magOwnerArraySize;
        if( dirOwnerArraySize > numOfOwner )
            numOfOwner = dirOwnerArraySize;

        double  magnitude = defaultMag;
        MVector direction = defaultDir;

        for (int ptIndex = 0; ptIndex < receptorSize; ptIndex ++ ) {
            if(receptorSize == magArraySize)
                magnitude = magnitudeArray[ptIndex];
            if(receptorSize == dirArraySize)
                direction = directionArray[ptIndex];
            if( numOfOwner > 0) {
                for( int nthOwner = 0; nthOwner < numOfOwner; nthOwner++ ) {
                if(magOwnerArraySize == numOfOwner)
                    magnitude = magnitudeOwnerArray[nthOwner];
                if(dirOwnerArraySize == numOfOwner)
                    direction = directionOwnerArray[nthOwner];
                outputForce.append( direction * magnitude );
            }
            } else {
                outputForce.append( direction * magnitude );
            }
        }
    }