hwDecalBumpShader_NV20.cpp

//-
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//
// NOTE: PLEASE READ THE README.TXT FILE FOR INSTRUCTIONS ON
// COMPILING AND USAGE REQUIREMENTS.
//
// DESCRIPTION: NV20-specific (Geforce3) sample shader.
//                              This shader can simultaneously display both decal 
//                              (base color) and bump textures.
//
//  This shader builds on the foundation demonstrated in the 
//  hwUnlitShader.
//
//      Additionally, this sample demonstrates how to:
//              - Use vendor-specific extensions, namely vertex programs,
//                texture shaders and register combiners, to achieve
//                effects that are impossible in standard OpenGL.
//              - Convert height field bump format (used by Maya) into
//                a normal map format, for real-time rendering.
//
//  Many parameters are easily customizable:
//              - The MNormalMapConverter::convertToNormalMap_InPlace()
//        bumpScale parameter is currently constant. You can change
//                it to a different value to increase or decrease the 
//                bumpiness.
//
//      PS: Thanks go to DAR from nVidia, for his help in making this
//      shader more robust. ;-)
//


// Uncomment the #ifdef below if you want to debug the vertex program by
// output a COL0 value that corresponds to an intermediate calculation.
// The only sane way we could find to debug that thing.
//#define DEBUGGING_VERTEX_PROGRAM 1

#ifdef WIN32
#pragma warning( disable : 4786 )               // Disable STL warnings.
#endif

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

#include <maya/MString.h>
#include <maya/MPlug.h>
#include <maya/MDagPath.h>
#include <maya/MDataBlock.h>
#include <maya/MDataHandle.h>
#include <maya/MArrayDataHandle.h>
#include <maya/MFnDependencyNode.h>
#include <maya/MFnNumericAttribute.h>
#include <maya/MFnTypedAttribute.h>
#include <maya/MFnLightDataAttribute.h>
#include <maya/MFloatVector.h>
#include <maya/MFnStringData.h>
#include <maya/MFnPlugin.h>
#include <maya/MGlobal.h>
#include <maya/MSceneMessage.h>

#include <maya/MPoint.h>
#include <maya/MMatrix.h>
#include <maya/MVector.h>
#include <maya/MEulerRotation.h>

// Include NVIDIA's helper libraries.  These libraries have
// copyright info in them so we cannot release them but we
// can use them to verify that the API works correctly.
//
#include <GL/gl.h>
#include <GL/glu.h>
#include <gl/glext.h>

#define GLH_EXT_SINGLE_FILE
#include "glh_extensions.h"
#undef GL_NV_vertex_array_range
#include "glh_genext.h"
#include "glh_obs.h"
using namespace glh;

#include "hwDecalBumpShader_NV20.h"
#include "ShadingConnection.h"

MTypeId hwDecalBumpShader_NV20::id( 0x00105441 );
/*static*/ const unsigned int hwDecalBumpShader_NV20::lookup_texture_size(256);


void hwDecalBumpShader_NV20::postConstructor( )
{
        setMPSafe(false);
}

// Static attribute instances.
//
MObject  hwDecalBumpShader_NV20::color;
MObject  hwDecalBumpShader_NV20::colorR;
MObject  hwDecalBumpShader_NV20::colorG;
MObject  hwDecalBumpShader_NV20::colorB;

MObject  hwDecalBumpShader_NV20::bump;
MObject  hwDecalBumpShader_NV20::bumpR;
MObject  hwDecalBumpShader_NV20::bumpG;
MObject  hwDecalBumpShader_NV20::bumpB;

MObject  hwDecalBumpShader_NV20::camera;
MObject  hwDecalBumpShader_NV20::cameraX;
MObject  hwDecalBumpShader_NV20::cameraY;
MObject  hwDecalBumpShader_NV20::cameraZ;

MObject  hwDecalBumpShader_NV20::light;
MObject  hwDecalBumpShader_NV20::lightX;
MObject  hwDecalBumpShader_NV20::lightY;
MObject  hwDecalBumpShader_NV20::lightZ;

MObject  hwDecalBumpShader_NV20::uCoord;
MObject  hwDecalBumpShader_NV20::vCoord;
MObject  hwDecalBumpShader_NV20::uvCoord;

MObject  hwDecalBumpShader_NV20::uBias;
MObject  hwDecalBumpShader_NV20::vBias;

MObject  hwDecalBumpShader_NV20::uvFilterSize;
MObject  hwDecalBumpShader_NV20::uvFilterSizeX;
MObject  hwDecalBumpShader_NV20::uvFilterSizeY;

MObject  hwDecalBumpShader_NV20::shininess;
MObject  hwDecalBumpShader_NV20::lightColor;
MObject  hwDecalBumpShader_NV20::lightColorR;
MObject  hwDecalBumpShader_NV20::lightColorG;
MObject  hwDecalBumpShader_NV20::lightColorB;

void hwDecalBumpShader_NV20::printGlError( const char *call )
{
    GLenum error;

        while( (error = glGetError()) != GL_NO_ERROR ) {
                assert(0);
            cerr << call << ":" << error << " is " << (const char *)gluErrorString( error ) << "\n";
        }
}


// The Vertex Program for the Decal Bump effect.
//
// CONSTANTS:
//  0- 3  4x4 ModelView-Projection composite matrix
//  4- 7  4x4 ModelView  matrix
//  8-10  light amb/diff/spec
// 11     light dir vector (from surface to light)

// VERTEX REGISTERS:
// 0 - coord
// 1 - normal
// 2 - texcoord0
// 3 - texcoord1
// 4 - texcoord2 (binorm)

// REGISTERS:
// 4 = eye space vertex coordinate
// 5 = eye space tangent vector
// 6 = eye space binormal vector
// 7 = eye space normal vector                  (VERIFIED)
// 8 = normalized eye space view vector (VERIFIED) (goes in the direction from vertex position to camera position)
// 9 = eye space half-angle vector
//
char vertexProgramString[] = 
        "!!VP1.0\n"

                // Multiply the vertex coords by the modelview-projection composite matrix,
                // to get clip space coordinates.
                "DP4   o[HPOS].x, c[0], v[0];"
                "DP4   o[HPOS].y, c[1], v[0];"
                "DP4   o[HPOS].z, c[2], v[0];"
                "DP4   o[HPOS].w, c[3], v[0];"

                // Multiply the vertex coords by the modelview matrix,
                // to get eye-space coordinates.
                "DP4   R4.x, c[4], v[0];"
                "DP4   R4.y, c[5], v[0];"
                "DP4   R4.z, c[6], v[0];"
                "DP4   R4.w, c[7], v[0];"

                // Multiply the normals by the modelview matrix,
                // resulting in eye-space normals.
                "DP3   R7.x, c[4], v[1];"
                "DP3   R7.y, c[5], v[1];"
                "DP3   R7.z, c[6], v[1];"
                // Re-normalize, in case the model-view matrix's is not a simple rotation.
                "DP3   R7.w, R7, R7;"                   
                "RSQ   R7.w, R7.w;"
                "MUL   R7.xyz, R7, R7.w;"

                // Multiply the binormals by the modelview matrix,
                // resulting in eye-space binormals.
                "DP3   R6.x, c[4], v[4];"
                "DP3   R6.y, c[5], v[4];"
                "DP3   R6.z, c[6], v[4];"
                // Re-normalize the binormals.
                "DP3   R6.w, R6, R6;"
                "RSQ   R6.w, R6.w;"
                "MUL   R6.xyz, R6, R6.w;"

                // Build tangent: tangent = binormal x normal.
                "MUL   R5, R6.zxyw, R7.yzxw;"
                "MAD   R5, R6.yzxw, R7.zxyw, -R5;"
                // put the sign in the tangent.
                "MUL   R5.xyz, R5, v[4].w;"
                // Re-normalize the tangent.
                "DP3   R5.w, R5, R5;"
                "RSQ   R5.w, R5.w;"
                "MUL   R5.xyz, R5, R5.w;"
                
                // Calculate eye space view vector.
                // (In essence, a normalization of the inverse
                //  of the vertex coordinate in eye-space)
                "DP3   R8.w, R4, R4;"
                "RSQ   R8.w, R8.w;"
                "MUL   R8.xyz, R4, -R8.w;"

                // Calculate (and normalize) tangent space half-angle vector.
                "ADD   R9, R8, c[11];"
                "DP3   R9.w, R9, R9;"
                "RSQ   R9.w, R9.w;"
                "MUL   R9.xyz, R9, R9.w;"

                // Transform half-angle vector into tangent space.
                "DP3   o[TEX3].x, R5, R9;"
                "DP3   o[TEX3].y, R6, R9;"
                "DP3   o[TEX3].z, R7, R9;"

                // Transform light direction vector into tangent space.
                "DP3   o[TEX2].x, R5, c[11];"
                "DP3   o[TEX2].y, R6, c[11];"
                "DP3   o[TEX2].z, R7, c[11];"

#ifndef DEBUGGING_VERTEX_PROGRAM
                // Put diffuse lighting into color.
                "DP3 o[COL0], R7, c[11];"
#else
                // VISUALIZE NORMAL VECTOR IN EYE SPACE
                "MOV o[COL0], R7;"
#endif          
                // Copy texcoords.
                "MOV o[TEX0], v[2];"
                "MOV o[TEX1], v[3];"

        "END";


// Load the vertexProgram and fill in the necessary constants used in the vertex program.
//
void hwDecalBumpShader_NV20::loadVertexProgramGL()
{
        GLenum error = glGetError();
        assert(!error);

        // If the vertex program hasn't been created yet, do it now.
        // Note that Maya shares textures, display lists and vertex programs
        // between all viewports, so this only need to be done once.
        if (vertex_program_id == 0)
    {
            glGenProgramsNV(1, &vertex_program_id);
        error = glGetError();
            assert(!error);

            // Attempt to load the program.
            unsigned int length = strlen(vertexProgramString);
            glLoadProgramNV(GL_VERTEX_PROGRAM_NV, vertex_program_id, length, (const GLubyte *) vertexProgramString);
            error = glGetError();
            assert(!error);

            if (error)
            {
                    // If an error occured, it's most likely due to a syntax or 
                    // logic error in the vertex program. The error position
                    // below will contain the index in the vertex program
                    // string that is faulty. See the NV_vertex_program
                    // extension specification for more details.
                    if (error == GL_INVALID_OPERATION)
                    {
                            int error_position = -2;

                            glGetIntegerv(GL_PROGRAM_ERROR_POSITION_NV, &error_position);
                    }
            }
    }

    // Set up the constant values.
        //
        // CONSTANTS:
        //  0- 3  4x4 ModelView-Projection composite matrix
        //  4- 7  4x4 ModelView  matrix
        //  8-10  light amb/diff/spec
        // 11     light dir vector (from surface to light)
        //
        glTrackMatrixNV(GL_VERTEX_PROGRAM_NV, 0, GL_MODELVIEW_PROJECTION_NV, GL_IDENTITY_NV);
        glTrackMatrixNV(GL_VERTEX_PROGRAM_NV, 4, GL_MODELVIEW, GL_IDENTITY_NV);
        glProgramParameter4fNV(GL_VERTEX_PROGRAM_NV, 8, 1, 1, 1, 1);
        glProgramParameter4fNV(GL_VERTEX_PROGRAM_NV, 9, 1, 1, 1, 1);
        glProgramParameter4fNV(GL_VERTEX_PROGRAM_NV, 10, 1, 1, 1, 1);
        glProgramParameter4fNV(GL_VERTEX_PROGRAM_NV, 11, -lightRotation[0], -lightRotation[1], -lightRotation[2], 0);   // light dir...
}


// Illumination (diffuse and specular) lookup table
// (This function assumes that lookup_image and lookup_texture have been deallocated.)
//
void hwDecalBumpShader_NV20::make_lookup_texture()
{
        // Re-calculate the look-up texture, if the shininess value/scale has changed.
        //
        float   shininessScale = 1.0f;
        MPlug   plug(thisMObject(), shininess);
        
        // Get the shininess scaling factor
        //
        MStatus status = plug.getValue(shininessScale);
        if (!status)
        {
                status.perror("hwDecalBumpShader_NV20::bind plug.getValue.");
                return;
        }

        if ( shininessScale < 0.01f )
        shininessScale = 0.01f;
        if ( shininessScale > 1.0f )
        shininessScale = 1.0f;

        // shininess factor is between 20 and 180
        //
        float shininessValue = 1.0f;
        shininessValue = 200.0f * (1.0f - 0.8f * shininessScale);

        // Only recompute the lookup texture if the values have changed since the last bind.
        if (shininessValue == currentShininessValue && shininessScale == currentShininessScale)
                return;
        
        currentShininessValue = shininessValue;
        currentShininessScale = shininessScale;

        unsigned int imgsize = lookup_texture_size;
        float imgsizeM1 = (float) (imgsize - 1);

        // Allocate the lookup_image and lookup_texture.
        if (lookup_table == NULL)
        lookup_table = new unsigned char[imgsize*imgsize*2];
        if (lookup_texture == NULL)
        lookup_texture = new tex_object_2D;

        // Fill it up.
        unsigned char * ip = lookup_table;
        for(int j=0; j < imgsize; j++)
        {
                unsigned char a = (unsigned char) (shininessScale * (255.0 * pow((j/imgsizeM1), shininessValue)));
                for(int i=0; i < imgsize; i++)
                {
                        *ip++ = (unsigned char) ((255.0 - 64) * (i/imgsizeM1)) + 64;
                        *ip++ = a;
                }
        }

        fLookupTextureReprocessed = true;

        return;
}

void hwDecalBumpShader_NV20::bind_lookup_table()
{
        make_lookup_texture();

        lookup_texture->bind();

        if (fLookupTextureReprocessed)
        {
                glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE_ALPHA, lookup_texture_size, lookup_texture_size, 0, GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, lookup_table); 
                fLookupTextureReprocessed = false;
        }

        lookup_texture->parameter(GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        lookup_texture->parameter(GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        lookup_texture->parameter(GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
        lookup_texture->parameter(GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
}

// Initialize the necessary OpenGL extensions
//
void hwDecalBumpShader_NV20::init_ext(const char * ext)
{
        if(!glh_init_extension(ext))
        { cerr << "Failed to initialize " << ext << "!" << endl; exit(0); }
}

hwDecalBumpShader_NV20::hwDecalBumpShader_NV20()
{
        // Get an reference to the singleton texture cache.
        m_pTextureCache = MTextureCache::instance();

        init_ext("GL_ARB_multitexture");
        init_ext("GL_NV_register_combiners");
        init_ext("GL_NV_vertex_program");

        isDirectionalLight = true;      // light's rotation is connected to the lightRotation attr

        // Set the shininess and shininess scale to absurd values, so that the
        // look-up table automatically get recomputed during the first update.
        currentShininessValue = -1.0;
        currentShininessScale = -1.0;
        lookup_texture = NULL;
        lookup_table   = NULL;
        fLookupTextureReprocessed = false;

        // Initialize callbacks.
        fBeforeNewCB = 0;
        fBeforeOpenCB = 0;
        fBeforeRemoveReferenceCB = 0;
        fMayaExitingCB = 0;
        attachSceneCallbacks();

    vertex_program_id = 0;              // handle for the Vertex Program
    
        // The vertex program will get loaded during the first refresh.
        // We cannot do it here since it's not guaranteed that the GL
        // context will be current at construction or destruction time 
        // (although it generally is).
}

hwDecalBumpShader_NV20::~hwDecalBumpShader_NV20()
{
        detachSceneCallbacks();
}

void hwDecalBumpShader_NV20::releaseEverything()
{
        release_lookup_texture();

        if (vertex_program_id > 0)
        {
                glFinish();

                // Unbind any program.
                glBindProgramNV(GL_VERTEX_PROGRAM_NV, 0);
                
                // Delete the program used by this shader.
                glDeleteProgramsNV(1, &vertex_program_id);

                // For sanity.
        vertex_program_id = 0;
        }

        // Release the texture cache through refcounting.
        m_pTextureCache->release();
        if(!MTextureCache::getReferenceCount())
        {
                m_pTextureCache = 0;
        }
}

void hwDecalBumpShader_NV20::attachSceneCallbacks()
{
        fBeforeNewCB             = MSceneMessage::addCallback(MSceneMessage::kBeforeNew,
                                                          releaseCallback, this);
        fBeforeOpenCB            = MSceneMessage::addCallback(MSceneMessage::kBeforeOpen,
                                                          releaseCallback, this);
        fBeforeRemoveReferenceCB = MSceneMessage::addCallback(MSceneMessage::kBeforeRemoveReference,
                                                          releaseCallback, this);
        fMayaExitingCB           = MSceneMessage::addCallback(MSceneMessage::kMayaExiting,
                                                          releaseCallback, this);
}

/*static*/
void hwDecalBumpShader_NV20::releaseCallback(void* clientData)
{
        hwDecalBumpShader_NV20 *pThis = (hwDecalBumpShader_NV20*) clientData;
        pThis->releaseEverything();
}

void hwDecalBumpShader_NV20::detachSceneCallbacks()
{
        if (fBeforeNewCB)
                MMessage::removeCallback(fBeforeNewCB);
        if (fBeforeOpenCB)
                MMessage::removeCallback(fBeforeOpenCB);
        if (fBeforeRemoveReferenceCB)
                MMessage::removeCallback(fBeforeRemoveReferenceCB);
        if (fMayaExitingCB)
                MMessage::removeCallback(fMayaExitingCB);

        fBeforeNewCB = 0;
        fBeforeOpenCB = 0;
        fBeforeRemoveReferenceCB = 0;
        fMayaExitingCB = 0;
}

MStatus initializePlugin( MObject obj )
{ 
        MStatus   status;
        
        const MString UserClassify( "shader/surface/utility" );

        MFnPlugin plugin( obj, PLUGIN_COMPANY, "4.5", "Any");
        status = plugin.registerNode( "hwDecalBumpShader_NV20", hwDecalBumpShader_NV20::id, 
                                              hwDecalBumpShader_NV20::creator, hwDecalBumpShader_NV20::initialize,
                                                                  MPxNode::kHwShaderNode, &UserClassify );
        if (!status) {
                status.perror("registerNode");
                return status;
        }

        return MS::kSuccess;
}

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

        plugin.deregisterNode( hwDecalBumpShader_NV20::id );
        if (!status) {
                status.perror("deregisterNode");
                return status;
        }

        return MS::kSuccess;
}


void * hwDecalBumpShader_NV20::creator()
{
    return new hwDecalBumpShader_NV20();
}

// Initialize the plug-in. Called once when the plug-in is loaded.
// This mostly involve creating attributes.
MStatus hwDecalBumpShader_NV20::initialize()
{
    MFnNumericAttribute nAttr; 
        MStatus status;
        MFnTypedAttribute sAttr; // For string attributes

    // Create input attributes

    colorR = nAttr.create( "colorR", "cr",MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(1.0f);

    colorG = nAttr.create( "colorG", "cg",MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(0.5f);

    colorB = nAttr.create( "colorB", "cb",MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(0.5f);

    color = nAttr.create( "color", "c", colorR, colorG, colorB);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(1.0f, 0.5f, 0.5f);
    nAttr.setUsedAsColor(true);

    bumpR = nAttr.create( "bumpR", "c2r",MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(1.0f);

    bumpG = nAttr.create( "bumpG", "c2g",MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(1.0f);

    bumpB = nAttr.create( "bumpB", "c2b",MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(1.0f);

    bump = nAttr.create( "bump", "c2", bumpR, bumpG, bumpB);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(1.0f, 1.0f, 1.0f);
    nAttr.setUsedAsColor(true);

    uCoord = nAttr.create( "uCoord", "u", MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(0.5f);

    vCoord = nAttr.create( "vCoord", "v", MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(0.5f);
 
    uvCoord = nAttr.create( "uvCoord","uv", uCoord, vCoord);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(0.5f, 0.5f );
    nAttr.setHidden(true);

    uBias = nAttr.create( "uBias", "bu", MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setMin(0.0f);
    nAttr.setMax(1.0f);
    nAttr.setKeyable(true);
    nAttr.setDefault(0.5f);

    vBias = nAttr.create( "vBias", "bv", MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setMin(0.0f);
    nAttr.setMax(1.0f);
    nAttr.setDefault(0.5f);

    uvFilterSizeX = nAttr.create( "uvFilterSizeX", "fsx", MFnNumericData::kFloat);
    nAttr.setStorable(false);
    nAttr.setReadable(true);
    nAttr.setWritable(true);
    nAttr.setHidden(true);

    uvFilterSizeY = nAttr.create( "uvFilterSizeY", "fsy", MFnNumericData::kFloat);
    nAttr.setStorable(false);
    nAttr.setReadable(true);
    nAttr.setWritable(true);
    nAttr.setHidden(true);

    uvFilterSize = nAttr.create("uvFilterSize","fs",uvFilterSizeX,uvFilterSizeY);
    nAttr.setStorable(false);
    nAttr.setReadable(true);
    nAttr.setWritable(true);
    nAttr.setHidden(true);

    lightX = nAttr.create( "lightX", "lgtx",MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(0.0f);

    lightY = nAttr.create( "lightY", "lgty",MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(1.0f);

    lightZ = nAttr.create( "lightZ", "lgtz",MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(1.0f);

    light = nAttr.create( "light", "lgt", lightX, lightY, lightZ);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(0.0f, 1.0f, 1.0f);

    cameraX = nAttr.create( "cameraX", "camx",MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(0.0f);

    cameraY = nAttr.create( "cameraY", "camy",MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(0.0f);

    cameraZ = nAttr.create( "cameraZ", "camz",MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(1.0f);

    camera = nAttr.create( "camera", "cam", cameraX, cameraY, cameraZ);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(0.0f, 0.0f, 1.0f);

    shininess = nAttr.create( "shininess", "sn", MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setMin(0.0f);
    nAttr.setMax(1.0f);
    nAttr.setDefault(0.5f);

    lightColorR = nAttr.create( "lightColorR", "lcr", MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(1.0f);

    lightColorG = nAttr.create( "lightColorG", "lcg", MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(1.0f);

    lightColorB = nAttr.create( "lightColorB", "lcb", MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(1.0f);

    lightColor = nAttr.create( "lightColor", "lc", lightColorR, lightColorG, lightColorB);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setDefault(1.0f, 1.0f, 1.0f);
    nAttr.setUsedAsColor(true);


 // create output attributes here
        // outColor is the only output attribute and it is inherited
        // so we do not need to create or add it.
        //

 // Add the attributes here

    addAttribute(color);

    addAttribute(bump);

    addAttribute(uvCoord);

    addAttribute(uBias);
    addAttribute(vBias);

    addAttribute(uvFilterSize);

        addAttribute(light);
        addAttribute(camera);
    addAttribute(shininess);
    addAttribute(lightColor);

    attributeAffects (colorR, outColor);
    attributeAffects (colorG, outColor);
    attributeAffects (colorB, outColor);
    attributeAffects (color,  outColor);
    attributeAffects (bumpR, outColor);
    attributeAffects (bumpG, outColor);
    attributeAffects (bumpB, outColor);
    attributeAffects (bump,  outColor);
    attributeAffects (uCoord,  outColor);
    attributeAffects (vCoord,  outColor);
    attributeAffects (uvCoord, outColor);
    attributeAffects (uBias,   outColor);
    attributeAffects (vBias,   outColor);

        attributeAffects (lightX,       outColor);
        attributeAffects (lightY,       outColor);
        attributeAffects (lightZ,       outColor);
        attributeAffects (light,        outColor);
        attributeAffects (cameraX,      outColor);
        attributeAffects (cameraY,      outColor);
        attributeAffects (cameraZ,      outColor);
        attributeAffects (camera,       outColor);

    attributeAffects (shininess,   outColor);
    attributeAffects (lightColorR, outColor);
    attributeAffects (lightColorG, outColor);
    attributeAffects (lightColorB, outColor);
    attributeAffects (lightColor,  outColor);

    return MS::kSuccess;
}


// This function gets called by Maya to evaluate the shader.
// See "Writing a shading node plug-in" in the documentation
// for more information.
//
//
MStatus hwDecalBumpShader_NV20::compute(
const MPlug&      plug,
      MDataBlock& block ) 
{ 
    bool k;
    k = (plug == outColor)  ||
        (plug == outColorR) ||
        (plug == outColorG) ||
        (plug == outColorB);
    if( !k )
        return MS::kUnknownParameter;

    // set output color attribute
    MDataHandle outColorHandle = block.outputValue( outColor );
    MFloatVector& outColor = outColorHandle.asFloatVector();
    outColor.x = 1.0;
    outColor.y = 0.5;
    outColor.z = 0.5;
    outColorHandle.setClean();
    return MS::kSuccess;
}


// To get 3 float values from the node attribute
//
MStatus hwDecalBumpShader_NV20::getFloat3(MObject attr, float value[3])
{
        MStatus status = MS::kSuccess;

        // Get the attr to use
        //
        MPlug   plug(thisMObject(), attr);

        MObject object;
        status = plug.getValue(object);
        if (!status)
        {
                status.perror("hwDecalBumpShader_NV20::getFloat3 plug.getValue.");
                return status;
        }

        MFnNumericData data(object, &status);
        if (!status)
        {
                status.perror("hwDecalBumpShader_NV20::getFloat3 construct data.");
                return status;
        }

        status = data.getData(value[0], value[1], value[2]);
        if (!status)
        {
                status.perror("hwDecalBumpShader_NV20::getFloat3 get values.");
                return status;
        }

        return status;
}

// To get a string value from the node attribute
//
MStatus hwDecalBumpShader_NV20::getString(MObject attr, MString &str)
{
        MPlug   plug(thisMObject(), attr);
        MStatus status = plug.getValue( str );

        return status;
}

/* virtual */
MStatus hwDecalBumpShader_NV20::bind(const MDrawRequest& request, M3dView& view)
{
        MStatus status;

        // Get the diffuse color
        //
        float diffuse_color[4];
        status = getFloat3(color, diffuse_color);
        diffuse_color[3] = 1.0;
        if (!status)
        return status;

        // Get the light color
        //
        float light_color[4];
        light_color[3] = 1.0f;
        status = getFloat3(lightColor, light_color);
        if (!status)
        return status;

        // Get the light direction (for directionalLight)
        //
        status = getFloat3(light, &lightRotation[0]);
        if (!status)
        return status;

        // Get the bumpScale value
        //
        float   bumpScaleValue = 2.0f;

        // Get the bumpMap type
        //
        bool    isHeightFieldMap = true;


        // Direction of the directional light
        //
        // Convert the light direction (which is assumed in originally be in world space, in euler coordinates) 
        // into an eye space vector.
        //
        double  scale = M_PI/180.0;             // Internal rotations are in radian and not in degrees
        MEulerRotation  lightRot( lightRotation[0] * scale, lightRotation[1] * scale, lightRotation[2] * scale );
        MVector light_v = MVector(0, 0, -1).rotateBy( lightRot );       // WS light vector

        MDagPath camDag;
        view.getCamera(camDag);

        light_v = light_v * camDag.inclusiveMatrixInverse();
        lightRotation[0] = (float) light_v[0];
        lightRotation[1] = (float) light_v[1];
        lightRotation[2] = (float) light_v[2];


        // Get the camera position
        //
        status = getFloat3(camera, &cameraPos[0]);
        if (!status)
        return status;

        // Get the decal and bump map file names
        //
        MString decalName = "";
        MString bumpName  = "";

        ShadingConnection colorConnection(thisMObject(), request.multiPath().partialPathName(), "color");
        ShadingConnection bumpConnection (thisMObject(), request.multiPath().partialPathName(), "bump");

        // If the color attribute is ultimately connected to a file texture, find its filename.
        // otherwise use the default color texture.
        if (colorConnection.type() == ShadingConnection::TEXTURE &&
                colorConnection.texture().hasFn(MFn::kFileTexture))
        {
                // Get the filename of the texture.
                MFnDependencyNode textureNode(colorConnection.texture());
                MPlug filenamePlug( colorConnection.texture(), textureNode.attribute(MString("fileTextureName")) );
                filenamePlug.getValue(decalName);
        }

        // If the bump attribute is ultimately connected to a file texture, find its filename.
        // otherwise use the default bump texture.
        if (bumpConnection.type() == ShadingConnection::TEXTURE &&
                bumpConnection.texture().hasFn(MFn::kFileTexture))
        {
                // Get the filename of the texture.
                MFnDependencyNode textureNode(colorConnection.texture());
                MPlug filenamePlug( bumpConnection.texture(), textureNode.attribute(MString("fileTextureName")) );
                filenamePlug.getValue(bumpName);
        }

        // Fail safe quit
        //
        if (bumpName.length() == 0 ||
                decalName.length() == 0)
        {
                view.beginGL();
                glPushAttrib( GL_ALL_ATTRIB_BITS );             // This might be too conservative
                glPushClientAttrib(GL_CLIENT_VERTEX_ARRAY_BIT);
                glColorMaterial(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE);
                glEnable(GL_COLOR_MATERIAL);
                glColor4fv(diffuse_color);
                view.endGL();
                return MS::kSuccess;
        }

        view.beginGL();

        glPushAttrib( GL_ALL_ATTRIB_BITS );
        glPushClientAttrib(GL_CLIENT_VERTEX_ARRAY_BIT);

    /* Starts Here... */
        glEnable(GL_TEXTURE_SHADER_NV);
        
        // stage 0 -- decal map
        glActiveTextureARB( GL_TEXTURE0_ARB );
        if(m_pTextureCache)
                m_pTextureCache->bind(colorConnection.texture(), MTexture::RGBA, false);
        glTexEnvi(GL_TEXTURE_SHADER_NV, GL_SHADER_OPERATION_NV, GL_TEXTURE_2D);
        
    // stage 1 -- bumpped normal map
        glActiveTextureARB( GL_TEXTURE1_ARB );
        // We need to be able to pass the bumpScaleValue
        // to the texture cache and rebuild the bump or normal map
        if( isHeightFieldMap ) {
                // convert the HeightField to the NormalMap
                if(m_pTextureCache)
                        m_pTextureCache->bind(bumpConnection.texture(), MTexture::NMAP, false);
        }
        else {
                if(m_pTextureCache)
                        m_pTextureCache->bind(bumpConnection.texture(), MTexture::RGBA, false);
        }
        glTexEnvi(GL_TEXTURE_SHADER_NV, GL_SHADER_OPERATION_NV, GL_TEXTURE_2D);
        
        // stage 2 -- dot product (diffuse component)
        glActiveTextureARB( GL_TEXTURE2_ARB );
        glTexEnvi(GL_TEXTURE_SHADER_NV, GL_SHADER_OPERATION_NV, GL_DOT_PRODUCT_NV);
        glTexEnvi(GL_TEXTURE_SHADER_NV, GL_RGBA_UNSIGNED_DOT_PRODUCT_MAPPING_NV, GL_EXPAND_NORMAL_NV);
        glTexEnvi(GL_TEXTURE_SHADER_NV, GL_PREVIOUS_TEXTURE_INPUT_NV, GL_TEXTURE1_ARB);

        // stage 3 -- dot product (specular component)
        glActiveTextureARB( GL_TEXTURE3_ARB );
        bind_lookup_table();    // 2D texture to get the diffuse and specular illumination
        glTexEnvi(GL_TEXTURE_SHADER_NV, GL_SHADER_OPERATION_NV, GL_DOT_PRODUCT_TEXTURE_2D_NV);
        glTexEnvi(GL_TEXTURE_SHADER_NV, GL_RGBA_UNSIGNED_DOT_PRODUCT_MAPPING_NV, GL_EXPAND_NORMAL_NV);
        glTexEnvi(GL_TEXTURE_SHADER_NV, GL_PREVIOUS_TEXTURE_INPUT_NV, GL_TEXTURE1_ARB);
        
        // With light color and intensity
        //
        glCombinerParameterfvNV(GL_CONSTANT_COLOR0_NV, diffuse_color);
        glCombinerParameterfvNV(GL_CONSTANT_COLOR1_NV, light_color);

        // The register combiner will do the multiplication between
        // the illumination and the decal color
        //
        glEnable(GL_REGISTER_COMBINERS_NV);

        
#ifndef DEBUGGING_VERTEX_PROGRAM
        glCombinerParameteriNV(GL_NUM_GENERAL_COMBINERS_NV, 2);
#else
        // For testing, only use one general register combiner.
        glCombinerParameteriNV(GL_NUM_GENERAL_COMBINERS_NV, 1);
#endif

        float constColor0[4];
        constColor0[0] = constColor0[1] = constColor0[2] = constColor0[3] = 1.0;
        glCombinerParameterfvNV(GL_CONSTANT_COLOR0_NV, constColor0);

#ifndef DEBUGGING_VERTEX_PROGRAM
        // Combiner stage 0 does the illumination modulation on the surface decal color
        //
        glCombinerInputNV(GL_COMBINER0_NV, GL_RGB, GL_VARIABLE_A_NV, GL_TEXTURE0_ARB, GL_UNSIGNED_IDENTITY_NV, GL_RGB);
        glCombinerInputNV(GL_COMBINER0_NV, GL_RGB, GL_VARIABLE_B_NV, GL_TEXTURE3_ARB, GL_UNSIGNED_IDENTITY_NV, GL_RGB);
        glCombinerInputNV(GL_COMBINER0_NV, GL_RGB, GL_VARIABLE_C_NV, GL_TEXTURE0_ARB, GL_UNSIGNED_IDENTITY_NV, GL_ALPHA);
        glCombinerInputNV(GL_COMBINER0_NV, GL_RGB, GL_VARIABLE_D_NV, GL_TEXTURE3_ARB, GL_UNSIGNED_IDENTITY_NV, GL_ALPHA);

        glCombinerOutputNV(GL_COMBINER0_NV, GL_RGB, GL_DISCARD_NV, GL_DISCARD_NV, GL_SPARE1_NV, 
                                           GL_NONE, GL_NONE, GL_FALSE, GL_FALSE, GL_FALSE);

        // Combiner stage 1, modulate the surface color by the light color
        //
        glCombinerInputNV(GL_COMBINER1_NV, GL_RGB, GL_VARIABLE_A_NV, GL_SPARE1_NV, GL_UNSIGNED_IDENTITY_NV, GL_RGB);
        glCombinerInputNV(GL_COMBINER1_NV, GL_RGB, GL_VARIABLE_B_NV, GL_CONSTANT_COLOR1_NV, GL_UNSIGNED_IDENTITY_NV, GL_RGB);

        glCombinerOutputNV(GL_COMBINER1_NV, GL_RGB, GL_DISCARD_NV, GL_DISCARD_NV, GL_SPARE1_NV, 
                                           GL_NONE, GL_NONE, GL_FALSE, GL_FALSE, GL_FALSE);
#else
        // Simplified register combiners to help debugging vertex program.
        glCombinerInputNV(GL_COMBINER0_NV, GL_RGB, GL_VARIABLE_A_NV, GL_PRIMARY_COLOR_NV, GL_UNSIGNED_IDENTITY_NV, GL_RGB);
        glCombinerInputNV(GL_COMBINER0_NV, GL_RGB, GL_VARIABLE_B_NV, GL_CONSTANT_COLOR0_NV, GL_UNSIGNED_IDENTITY_NV, GL_RGB);
        glCombinerInputNV(GL_COMBINER0_NV, GL_RGB, GL_VARIABLE_C_NV, GL_TEXTURE0_ARB, GL_UNSIGNED_IDENTITY_NV, GL_ALPHA);
        glCombinerInputNV(GL_COMBINER0_NV, GL_RGB, GL_VARIABLE_D_NV, GL_TEXTURE3_ARB, GL_UNSIGNED_IDENTITY_NV, GL_ALPHA);

        glCombinerOutputNV(GL_COMBINER0_NV, GL_RGB, GL_SPARE1_NV, GL_DISCARD_NV, GL_DISCARD_NV, 
                                           GL_NONE, GL_NONE, GL_FALSE, GL_FALSE, GL_FALSE);
#endif // DEBUGGING_VERTEX_PROGRAM

        // The final Combiner just pass through
        //
        glFinalCombinerInputNV(GL_VARIABLE_A_NV, GL_ZERO, GL_UNSIGNED_IDENTITY_NV, GL_RGB);
        glFinalCombinerInputNV(GL_VARIABLE_B_NV, GL_ZERO, GL_UNSIGNED_IDENTITY_NV, GL_RGB);
        glFinalCombinerInputNV(GL_VARIABLE_C_NV, GL_ZERO, GL_UNSIGNED_IDENTITY_NV, GL_RGB);
        glFinalCombinerInputNV(GL_VARIABLE_D_NV, GL_SPARE1_NV, GL_UNSIGNED_IDENTITY_NV, GL_RGB);

        view.endGL();

        return MS::kSuccess;
}


/* virtual */
MStatus hwDecalBumpShader_NV20::unbind(const MDrawRequest& request,
                           M3dView& view)
{
        view.beginGL();
        
        glDisable(GL_REGISTER_COMBINERS_NV);
        glDisable(GL_TEXTURE_SHADER_NV);

        glActiveTextureARB( GL_TEXTURE0_ARB );

        glPopClientAttrib();
        glPopAttrib();

        view.endGL();

        return MS::kSuccess;
}

// Compute array of binormals. Return the pointer to the array if succesful,
// NULL otherwise.
float* hwDecalBumpShader_NV20::computeBinormals(int indexCount,
                                                                                   const unsigned int * indexArray,
                                                                                   int vertexCount,
                                                                                   const float* vertexArray, 
                                                                                   const float* normalArray, 
                                                                                   const float* texCoordArray)
{
        // Allocate the array of binormals.
        float *biNormalArray = new float[3*vertexCount];

        // Allocate space for a triangle of vertices, textures, normals, binormals.
        // This triangle will be used to compute the binormal vector.
        //
        const float *   v[3];   // Vertex               (x,y,z)
        const float *   t[3];   // Texture              (s,t)
        const float *   n[3];   // Normal               (x,y,z)
        float *                 b[3];   // BiNormal             (x,y,z)
        
        for (int i = 0; i < indexCount; i += 3)
        {
                int i0 = indexArray[i+0];
                int i1 = indexArray[i+1];
                int i2 = indexArray[i+2];
                
                // Get the xyz coords of the corners of the triangle.
                //
                v[0] = vertexArray + 3 * i0;
                v[1] = vertexArray + 3 * i1;
                v[2] = vertexArray + 3 * i2;
                
                // Get the st coords of the corners of the triangle.
                //
                t[0] = texCoordArray + 2 * i0;
                t[1] = texCoordArray + 2 * i1;
                t[2] = texCoordArray + 2 * i2;
                
                // Get the normals at the corners of the triangle.
                //
                n[0] = normalArray + 3 * i0;
                n[1] = normalArray + 3 * i1;
                n[2] = normalArray + 3 * i2;
                
                // Get pointers to the binormal vectors.
                //
                b[0] = biNormalArray + 3 * i0;
                b[1] = biNormalArray + 3 * i1;
                b[2] = biNormalArray + 3 * i2;
                
                // *********************************************
                // ******** compute the binormal vector ********
                // *********************************************
                vec3f   plane[3];
                vec3f   c0, c1, c2;
                vec3f   s0, s1;
                
                // Calculate plane equations for the planes defined
                // by the (x, s, t), (y, s, t), and (z, s, t) coords.
                int idx;
                for (idx = 0; idx < 3; ++idx)
                {
                        // Set up the three corners
                        c0.set_value(v[0][idx], t[0][0], t[0][1]);
                        c1.set_value(v[1][idx], t[1][0], t[1][1]);
                        c2.set_value(v[2][idx], t[2][0], t[2][1]);
                        
                        // Calculate two sides
                        s0 = c0 - c2;
                        s1 = c1 - c2;
                        
                        // Calculate the normal of the plane
                        plane[idx] = s1.cross(s0);
                }
                
                // Now solve for the texture gradients dsdx, dsty, dsdt, ...
                vec3f ds, dt, dn;
                
                for (idx = 0; idx < 3; ++idx)
                {
                        ds[idx] = -plane[idx][1]/plane[idx][0];
                        dt[idx] = -plane[idx][2]/plane[idx][0];
                }

                dt.normalize();
                dn = ds.cross(dt);
        
                // Make sure that our computed normal vector points in the
                // same direction as the input normal vector.
                vec3f normal(n[0]);
                if (normal.dot(dn) < 0)
                {
                        // They pointed in different directions, negate
                        ds.negate();
                        dt.negate();
                        dn.negate();
                }
                
                // Compute the biNormal vector and store them in the biNormal array
                for (idx = 0; idx < 3; ++idx)
                {
                        vec3f vn = n[idx];
                        vec3f vb = vn.cross( dt );
                        vb.normalize();
                        
                        for( int j = 0; j < 3; ++j )
                                b[idx][j] = vb[j];
                }
        }

        return biNormalArray;
}


/* virtual */
MStatus hwDecalBumpShader_NV20::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)
{
        // We assume triangles here.
        //
        if (prim != GL_TRIANGLES)
                return MS::kSuccess;            

        view.beginGL();

        // Bind the vertex program. Note that this will automatically
        // create and compile the vertex program, the first time
        // this function gets called.
        //
    loadVertexProgramGL();

        // Bind and enable the vertex program
        //
        glBindProgramNV(GL_VERTEX_PROGRAM_NV, vertex_program_id);
        glEnable(GL_VERTEX_PROGRAM_NV);

        // VERTEX REGISTERS (Attributes):
        // 0 - coord
        // 1 - normal
        // 2 - texcoord0 (decal 2D texture)
        // 3 - texcoord1 (bump 2D texture)
        // 4 - texcoord2 (binormal vector (in object space))
        glVertexAttribPointerNV( 0, 3, GL_FLOAT, 0, vertexArray );
        glVertexAttribPointerNV( 1, 3, GL_FLOAT, 0, normalArrays[0] );
        glVertexAttribPointerNV( 2, 2, GL_FLOAT, 0, texCoordArrays[0] );
        glVertexAttribPointerNV( 3, 2, GL_FLOAT, 0, texCoordArrays[0] );
        glVertexAttribPointerNV( 4, 3, GL_FLOAT, 0, normalArrays[2] );

        glEnableClientState( GL_VERTEX_ATTRIB_ARRAY0_NV );
        glEnableClientState( GL_VERTEX_ATTRIB_ARRAY1_NV );
        glEnableClientState( GL_VERTEX_ATTRIB_ARRAY2_NV );
        glEnableClientState( GL_VERTEX_ATTRIB_ARRAY3_NV );
        glEnableClientState( GL_VERTEX_ATTRIB_ARRAY4_NV );

        glDrawElements(GL_TRIANGLES, indexCount, GL_UNSIGNED_INT, indexArray);

        glDisableClientState( GL_VERTEX_ATTRIB_ARRAY0_NV );
        glDisableClientState( GL_VERTEX_ATTRIB_ARRAY1_NV );
        glDisableClientState( GL_VERTEX_ATTRIB_ARRAY2_NV );
        glDisableClientState( GL_VERTEX_ATTRIB_ARRAY3_NV );
        glDisableClientState( GL_VERTEX_ATTRIB_ARRAY4_NV );

        glDisable(GL_VERTEX_PROGRAM_NV);

        glClientActiveTextureARB(GL_TEXTURE0_ARB);

        view.endGL();

        return MS::kSuccess;
}

/* virtual */
int             hwDecalBumpShader_NV20::normalsPerVertex()
{
        return 3;
}

/* virtual */
int             hwDecalBumpShader_NV20::texCoordsPerVertex()
{
        return 1;
}

// Release the lookup texture/image.
void hwDecalBumpShader_NV20::release_lookup_texture()
{
        if (lookup_table)
        {
                delete lookup_table;
                lookup_table = NULL;
        }
        
        if (lookup_texture)
        {
                delete lookup_texture;
                lookup_table = NULL;
        }
}