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# blindDataShader.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.
    // ==========================================================================
    //+

    #ifdef WIN32
    #pragma warning( disable : 4786 )
    #endif

    #include <maya/MIOStream.h>
    #include <maya/MDagPath.h>
    #include <maya/MDoubleArray.h>
    #include <maya/MFloatVector.h>
    #include <maya/MFnDependencyNode.h>
    #include <maya/MFnLightDataAttribute.h>
    #include <maya/MFnMesh.h>
    #include <maya/MFnNumericAttribute.h>
    #include <maya/MFnTypedAttribute.h>
    #include <maya/MGlobal.h>
    #include <maya/MPlug.h>
    #include <maya/MPlugArray.h>
    #include <maya/MString.h>

    #if defined(OSMac_MachO_)
    #include <OpenGL/gl.h>
    #include <OpenGL/glu.h>
    #else
    #include <GL/gl.h>
    #include <GL/glu.h>
    #endif

    #include "blindDataShader.h"

    void mergeSort( int startIndex, int sortingOffset,
                    MIntArray& sortingArray, int* tempSortingArray,
                    MDoubleArray& otherArray, double* tempOtherArray)
    //
    // Description:
    // This is a very dirty recursive implementation of the merge sort
    // that is very application-specific
    //
    {
        if (sortingOffset == 2)
        {
            if (sortingArray[startIndex] > sortingArray[startIndex+1])
            {
                int temp = sortingArray[startIndex+1];
                sortingArray[startIndex+1] = sortingArray[startIndex];
                sortingArray[startIndex] = temp;
                double ftemp = otherArray[startIndex+1];
                otherArray[startIndex+1] = otherArray[startIndex];
                otherArray[startIndex] = ftemp;
            }
        }
        else if (sortingOffset > 2)
        {
            // First, sort each half
            //
            int leftCount = sortingOffset / 2;
            int rightCount = sortingOffset - leftCount;
            int leftIndex = startIndex;
            int rightIndex = startIndex + leftCount;
            mergeSort(leftIndex, leftCount, sortingArray, tempSortingArray,
                otherArray, tempOtherArray);
            mergeSort(rightIndex, rightCount, sortingArray, tempSortingArray,
                otherArray, tempOtherArray);

            // Second, merge the halves into the temporary arrays
            //
            int index = startIndex;
            while (leftIndex < (startIndex + leftCount)
                && rightIndex < (startIndex + sortingOffset) )
            {
                if (sortingArray[leftIndex] < sortingArray[rightIndex])
                {
                    tempSortingArray[index] = sortingArray[leftIndex];
                    tempOtherArray[index++] = otherArray[leftIndex++];
                }
                else
                {
                    tempSortingArray[index] = sortingArray[rightIndex];
                    tempOtherArray[index++] = otherArray[rightIndex++];
                }
            }

            // One of the sides is done, so add the other side
            //
            while (leftIndex < (startIndex + leftCount) )
            {
                tempSortingArray[index] = sortingArray[leftIndex];
                tempOtherArray[index++] = otherArray[leftIndex++];
            }
            while (rightIndex < (startIndex + sortingOffset) )
            {
                tempSortingArray[index] = sortingArray[rightIndex];
                tempOtherArray[index++] = otherArray[rightIndex++];
            }

            // Finally, copy the temporary sorting array over to the other side
            //
            for (index = startIndex; index < (startIndex + sortingOffset); ++index)
            {
                sortingArray[index] = tempSortingArray[index];
                otherArray[index] = tempOtherArray[index];
            }
        }
    }

    int binarySearch(int searchValue, MIntArray& searchArray)
    //
    // Description:
    // Application-specific implementation of the binary search algorithm.
    // It returns the index in the "searchArray" where the "searchValue"
    // is found or -1 if it is not found.
    //
    {
        int max = searchArray.length();
        int min = 0;
        while (max - min > 1)
        {
            int currentIndex = ((max - min) / 2) + min;
            int currentValue = searchArray[currentIndex];
            if (currentValue == searchValue) return currentIndex;
            else if (currentValue < searchValue) min = currentIndex;
            else max = currentIndex;
        }
        if (searchArray[min] == searchValue) return min;
        else return -1;
    }

    /****************************************************************************
     * Blind Data Shader class
     ***************************************************************************/

    // Static class member variables
    //
    // Unique Node TypeId
    MTypeId blindDataShader::id( 0x00086000 );

    void* blindDataShader::creator()
    //
    // Description: Static member function that returns a new
    // dynamically-allocated instance of the class.
    //
    {
        return new blindDataShader();
    }

    MStatus blindDataShader::initialize()
    //
    // Description: Static member function that initializes the static
    // member variables of the class. In this case, it does nothing, since
    // "id" is already set to the default value.
    //
    {
        return MS::kSuccess;
    }

    MStatus blindDataShader::compute(
    const MPlug&      plug,
          MDataBlock& block )
    {
        bool k = false;
        k |= (plug==outColor);
        k |= (plug==outColorR);
        k |= (plug==outColorG);
        k |= (plug==outColorB);
        if( !k ) return MS::kUnknownParameter;

        // Always return black for now.
        MFloatVector resultColor(0.0,0.0,0.0);

        // set ouput color attribute
        MDataHandle outColorHandle = block.outputValue( outColor );
        MFloatVector& outColor = outColorHandle.asFloatVector();
        outColor = resultColor;
        outColorHandle.setClean();

        return MS::kSuccess;
    }

    MStatus blindDataShader::bind(const MDrawRequest& request, M3dView& view)
    {
        view.beginGL();

        glPushAttrib( GL_ALL_ATTRIB_BITS );
        glPushClientAttrib(GL_CLIENT_VERTEX_ARRAY_BIT);

        view.endGL();

        return MS::kSuccess;
    }

    MStatus blindDataShader::unbind(const MDrawRequest& request,
                   M3dView& view)
    {
        view.beginGL();

        glPopClientAttrib();
        glPopAttrib();

        view.endGL();

        return MS::kSuccess;
    }

    MStatus blindDataShader::geometry( const MDrawRequest& request,
                                    M3dView& view,
                                    int prim,
                                    unsigned int writable,
                                    int indexCount,
                                    const unsigned int * indexArray,
                                    int vertexCount,
                                    const int * vertexIDs,
                                    const float * vertexArray,
                                    int normalCount,
                                    const float ** normalArrays,
                                    int colorCount,
                                    const float ** colorArrays,
                                    int texCoordCount,
                                    const float ** texCoordArrays)
    //
    // Description:
    // Once everything is plugged, this function is called by the Maya rendering
    // engine to render the given objects. It will be called for each frame, so
    // the efficiency of this algorithm is important.
    //
    {
        const int blindDataUniqueID = 60;
        MStatus stat;
        int i;

        // Create our own empty colour array and
        // populate it with the default colour value for the attribute.
        //
        double* colours = new double[vertexCount * 3];
        float defaultColour[3] = { 0.0f, 0.0f, 0.0f };
        MPlug plug( thisMObject(), outColor );
        MObject colorObject;
        plug.getValue(colorObject);
        MFnNumericData data(colorObject);
        data.getData(defaultColour[0], defaultColour[1], defaultColour[2]);

        // Use the blind data to set independant colour values
        //
        MFnMesh mesh(request.multiPath().node(), &stat);
        if (stat && mesh.hasBlindData(MFn::kMeshVertComponent, &stat)
            && mesh.hasBlindData(vertexIDs[0], MFn::kMeshVertComponent,
            blindDataUniqueID, &stat))
        {
            MIntArray redComponentIDs, greenComponentIDs, blueComponentIDs;
            MDoubleArray redColour, greenColour, blueColour;

            stat = mesh.getDoubleBlindData( MFn::kMeshVertComponent,
                blindDataUniqueID, "red", redComponentIDs, redColour);
            if (stat) stat = mesh.getDoubleBlindData( MFn::kMeshVertComponent,
                blindDataUniqueID, "green", greenComponentIDs, greenColour);
            if (stat) stat = mesh.getDoubleBlindData( MFn::kMeshVertComponent,
                blindDataUniqueID, "blue", blueComponentIDs, blueColour);

            if (stat && redComponentIDs.length() == redColour.length()
                && greenComponentIDs.length() == greenColour.length()
                && blueComponentIDs.length() == blueColour.length())
            {
                // Now that I have all the blind data,
                // use the vertex IDs and the component IDs arrays
                // to map the blind data values inside the colour array.
                //

                // Sort the components IDs and the colour values in increasing
                // order to speed up the association
                //
                int maxArrayLength =
                    (redComponentIDs.length() > greenComponentIDs.length()) ?
                    ((redComponentIDs.length() > blueComponentIDs.length()) ?
                        redComponentIDs.length() : blueComponentIDs.length()) :
                    ((greenComponentIDs.length() > blueComponentIDs.length()) ?
                        greenComponentIDs.length() : blueComponentIDs.length());
                int* tempIntArray = new int[maxArrayLength];
                double* tempFloatArray = new double[maxArrayLength];
                mergeSort(0, redComponentIDs.length(), redComponentIDs,
                    tempIntArray, redColour, tempFloatArray);
                mergeSort(0, greenComponentIDs.length(), greenComponentIDs,
                    tempIntArray, greenColour, tempFloatArray);
                mergeSort(0, blueComponentIDs.length(), blueComponentIDs,
                    tempIntArray, blueColour, tempFloatArray);

                // Associate the vertex IDs with the colour values
                //
                for (i = 0; i < vertexCount; ++i)
                {
                    int index = binarySearch(vertexIDs[i], redComponentIDs);
                    if (index != -1) colours[3*i] = redColour[index];
                    else colours[3*i] = defaultColour[0];

                    index = binarySearch(vertexIDs[i], greenComponentIDs);
                    if (index != -1) colours[3*i+1] = greenColour[index];
                    else colours[3*i+1] = defaultColour[1];

                    index = binarySearch(vertexIDs[i], blueComponentIDs);
                    if (index != -1) colours[3*i+2] = blueColour[index];
                    else colours[3*i+2] = defaultColour[2];
                }
            }
        }

        // Render the triangles using the new vertex colour information
        // taken from the blind data values of the mesh
        //
        view.beginGL();

        glPushAttrib( GL_ALL_ATTRIB_BITS );
        glPushClientAttrib(GL_CLIENT_VERTEX_ARRAY_BIT);

        glDisable(GL_LIGHTING);

        glVertexPointer(3, GL_FLOAT, 0, vertexArray);
        glEnableClientState(GL_VERTEX_ARRAY);

        // Is the next line necessary?
        glColor4f( 1.0f, 1.0f, 1.0f, 1.0f );

        glColorPointer(3, GL_DOUBLE, 0, colours);
        glEnableClientState(GL_COLOR_ARRAY);

        glDrawElements(prim, indexCount, GL_UNSIGNED_INT, indexArray);

        glDisable(GL_COLOR_MATERIAL);

        glPopClientAttrib();
        glPopAttrib();

        view.endGL();

        return MS::kSuccess;
    }