hwRefractReflectShader_NV20/hwRefractReflectShader_NV20.cpp
 
 
 
hwRefractReflectShader_NV20/hwRefractReflectShader_NV20.cpp
//-
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// material (collectively the "Data") in these files contain unpublished 
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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 produces reflection and refraction effects.
//
//  This shader builds on the foundation demonstrated in the hwUnlitShader.
//
//

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

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

#include <maya/MString.h>
#include <maya/MPlug.h>
#include <maya/MDagPath.h>
#include <maya/MFnDependencyNode.h>
#include <maya/MFnNumericAttribute.h>
#include <maya/MFnTypedAttribute.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/MQuaternion.h>
#include <maya/MEulerRotation.h>

#include <GL/gl.h>
#include <GL/glext.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.
//
#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 "hwRefractReflectShader_NV20.h"
#include "ShadingConnection.h"

MTypeId hwRefractReflectShader_NV20::id( 0x00105445 );


void hwRefractReflectShader_NV20::postConstructor( )
{
        setMPSafe(false);
}

// Static attribute instances.
//
MObject  hwRefractReflectShader_NV20::color;
MObject  hwRefractReflectShader_NV20::colorR;
MObject  hwRefractReflectShader_NV20::colorG;
MObject  hwRefractReflectShader_NV20::colorB;

MObject  hwRefractReflectShader_NV20::refractionIndex;
MObject  hwRefractReflectShader_NV20::reflectivity;



// The Vertex Program for the reflection&refraction shading effect.
//
// CONSTANTS:
//  0- 3        4x4 ModelView-Projection composite matrix
//  4- 7        4x4 ModelView   inverseTranspose matrix
//  8- 11       4x4 ModelView   matrix
//  12-15       4x4 Texture             matrix
//
// 58   refraction index [rIdx, rIdx*rIdx, 0.0, 0.0]
// 59   camera position in eye space [0.0, 0.0, 0.0, 1.0]  
//              (camera could be offseted if necessary, should work but untested)
//
// 64   misc constants [0.0, 1.0, 2.0, 3.0]


// VERTEX REGISTERS (mapped so that standard gl calls work):
// 0 - coord
// 2 - normal
//
// RESULTS:
// texcoord0    (Refraction coords in eye-space)
// texcoord1    (Reflection coords in eye-space)
//
char vertexProgramString[] = 

                "!!VP1.0 # Refraction and Reflection\n"

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

                // =====================================================
                // The rest of the computations are done in the eyeSpace
                // =====================================================

        // Transform, vertex position to eye space, with the MODELVIEW matrix
                //
                "DP4    R9.x, c[8],  v[OPOS];"
                "DP4    R9.y, c[9],  v[OPOS];"
                "DP4    R9.z, c[10], v[OPOS];"
                "DP4    R9.w, c[11], v[OPOS];"          // R9 = eye space Position of this vertex

                // Using the inverseTranspose of the MODELVIEW matrix,
        // transform the vertex normal to eye space and normalize it
                //
                "DP3    R0.x, c[4], v[NRML];"
                "DP3    R0.y, c[5], v[NRML];"
                "DP3    R0.z, c[6], v[NRML];"
        "DP3    R11.w, R0, R0;"
                "RSQ    R11.w, R11.w;"
                "MUL    R11, R0, R11.w;"                        // R11 = normalized normal vector in the eyeSpace

                // Compute the 'vertex->eye' vector and normalize it
                //
                "ADD    R0, -R9, c[59];"                        // c[59] = eye position in eye space (0,0,0,1)
        "DP3    R8.w, R0, R0;"
                "RSQ    R8.w, R8.w;"
                "MUL    R8, R0, R8.w;"                          // R8 = the eye/incident vector (I)

        // Calculate REFRACTION: Renderman style
                // float        eta;    // the refraction index value
                //
        // float        IdotN = I.N;
        // float        k = 1 - eta*eta*(1 - IdotN*IdotN);
        // return       k < 0 ? (0,0,0) : eta*I - (eta*IdotN + sqrt(k))*N;
                //
                "DP3    R0.x, R11, -R8;"                                // R0 = N.I
        //
                "MAD    R1.x, -R0.x, R0.x, c[64].y;"    // R1.x = (1 - IdotN * IdotN)           == SQR( sin(Ti) )
                "MUL    R1.x, R1.x, c[58].y;"                   // R1.x = R1.x * eta*eta
        "ADD    R1.x, c[64].y, -R1.x;"                  // R1.x = (1 - (R1.x * eta * eta) )     == 1 - SQR( eta * sin(Ti) )
        //
        "RSQ    R2.x, R1.x;"                                    // R2.x = 1 / SQRT(R1.x)
        "RCP    R2.x, R2.x;"                                    // R2.x = cos(Tr) = SQRT(R1.x)  <=== OK
        "MAD    R2.x, c[58].x, R0.x, R2.x;"             // R2.x = eta*(IdotN) + cos(Tr)
        "MUL    R2, R11, R2.x;"                                 // R2 = N * R2.x
        "MAD    R2, c[58].x, -R8, R2;"                  // R2 is the refracted ray direction
                //
        // Transform refracted ray by cubemap transform (texture matrix)
                //
        "DP3    o[TEX0].x, c[12], R2;"
        "DP3    o[TEX0].y, c[13], R2;"
        "DP3    o[TEX0].z, c[14], R2;"

        // Calculate REFLECTION in cubeMap space
        //
        "MUL    R0, R11, c[64].z;"              // R0   = 2*N
        "DP3    R3.w, R11, R8;"                 // R3.w = N.dot.I
        "MAD    R3, R3.w, R0, -R8;"             // R3   = 2*N*(N.dot.I) - I
                //
        // Transform reflected ray by cubemap transform (texture matrix)
                //
        "DP3    o[TEX1].x, c[12], R3;"
        "DP3    o[TEX1].y, c[13], R3;"
        "DP3    o[TEX1].z, c[14], R3;"

        "END";




void initVertexProgram(const char vertexProgramCode[], GLuint* pVertexProgramId)
{
        // Allocate and initialize the vertex program.
        glGenProgramsNV(1, pVertexProgramId);
        GLenum error = glGetError();
        assert(error == GL_NO_ERROR);

        // Load the program.
        unsigned int length = strlen(vertexProgramCode);
        glLoadProgramNV(GL_VERTEX_PROGRAM_NV, *pVertexProgramId, length, 
                (const GLubyte *) vertexProgramCode);
        error = glGetError();

        // If an error occured, find the location in the vertex program
        // code and assert.
        if (error != GL_NO_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);

                        // Most likely a bug in the vertex program code...
                        assert(0);
                }
        }
}

// Load the vertexProgram and fill in the necessary constants used in the vertex program.
//
void hwRefractReflectShader_NV20::loadVertexProgramGL( M3dView& view )
{
        view.beginGL();
        {
                // Don't load/initialize the vertex program more than once.
                //
                if (vertex_program_id == 0)     
                        initVertexProgram(vertexProgramString, &vertex_program_id);

                // Set up the constant values.
                //
                // CONSTANTS:
                //  0- 3        4x4 ModelView-Projection composite matrix
                //  4- 7        4x4 ModelView   inverseTranspose matrix
                //  8- 11       4x4 ModelView   matrix
                //  12-15       4x4 Texture             matrix
                //
                glTrackMatrixNV(GL_VERTEX_PROGRAM_NV, 0,  GL_MODELVIEW_PROJECTION_NV, GL_IDENTITY_NV);
                glTrackMatrixNV(GL_VERTEX_PROGRAM_NV, 4,  GL_MODELVIEW,               GL_INVERSE_TRANSPOSE_NV);
                glTrackMatrixNV(GL_VERTEX_PROGRAM_NV, 8,  GL_MODELVIEW,               GL_IDENTITY_NV);
                glTrackMatrixNV(GL_VERTEX_PROGRAM_NV, 12, GL_TEXTURE,                 GL_IDENTITY_NV);
                
                float rIdx = fRefractionIndex;
                glProgramParameter4fNV(GL_VERTEX_PROGRAM_NV, 58, rIdx, rIdx*rIdx, 0.0, 0.0);    // refraction index
                glProgramParameter4fNV(GL_VERTEX_PROGRAM_NV, 59, 0.0, 0.0, 0.0, 1.0);                   // eye position
                glProgramParameter4fNV(GL_VERTEX_PROGRAM_NV, 64, 0.0, 1.0, 2.0, 3.0);                   // misc constants
        }
        view.endGL();
}

// Load the file textures for the cube maps.
//
MStatus hwRefractReflectShader_NV20::loadTextures(const MDrawRequest& request, M3dView& view)
{
        // Get the cube map file names
        //
        MStringArray    decalNames;
        MString                 decalName;

        // Find the cubemap textures by tracing through the connection from the color atttribute
        //
        ShadingConnection       colorConnection(thisMObject(), request.multiPath().partialPathName(), "color");

        // If the color attribute is ultimately connected to a environment, 
        // find its filenames, otherwise use the default color texture.
        //
        bool gotAllEnvironmentMaps = TRUE;
        if (colorConnection.type() == ShadingConnection::TEXTURE &&
                colorConnection.texture().hasFn(MFn::kEnvCube))
        {
                // Get the filenames of the texture.
                MFnDependencyNode textureNode(colorConnection.texture());
                MString attributeName;
                MString envNames[6] = { "top", "bottom", "left", "right", "front", "back" };

                // Scan for connected file textures to the environment map node
                //
                for (int i=0; i<6; i++)
                {
                        ShadingConnection conn(colorConnection.texture(), request.multiPath().partialPathName(), 
                                                        envNames[i]);

                        if (conn.type() == ShadingConnection::TEXTURE &&
                                conn.texture().hasFn(MFn::kFileTexture))
                        {
                                MFnDependencyNode envNode(conn.texture());
                                MPlug filenamePlug( conn.texture(), envNode.attribute(MString("fileTextureName")) );

                                filenamePlug.getValue(decalName);

                                if (decalName.length() == 0)    decalName = "internalDefaultTexture";

                                // Append next environment map name
                                decalNames.append( decalName );
                        }

                        // If any of the environment maps are not mapped put in a fake texture
                        else
                        {
                                decalName = "internalDefaultTexture";
                                decalNames.append( decalName );
                        }
                }
        }
        else
        {
                // Put in a fake texture for each side
                decalName = "internalDefaultTexture";
                for (int i=0; i<6; i++)
                {
                        decalNames.append( decalName );
                }
        }

        // Reload cube maps if the name of the textures
        // for any of the cube maps changes
        //
        bool reload = FALSE;
        for (int i=0; i<6; i++)
        {
                if (currentTextureNames[i] != decalNames[i])
                {
                        reload = TRUE;
                        break;
                }
        }

        view.beginGL();
        {
                if ( reload )
                {
                        MString ypTexName(decalNames[0]);       // y+ == top
                        MString ynTexName(decalNames[1]);       // y- == bottom
                        MString xpTexName(decalNames[2]);       // x+ == left
                        MString xnTexName(decalNames[3]);       // x- == right
                        MString zpTexName(decalNames[4]);       // z+ == front
                        MString znTexName(decalNames[5]);       // z- == back

                        MStatus stat;
                        if (! (stat = theImage_XP.readFromFile(xpTexName)) )    return MS::kFailure;
                        if (! (stat = theImage_XN.readFromFile(xnTexName)) )    return MS::kFailure;
                        if (! (stat = theImage_YP.readFromFile(ypTexName)) )    return MS::kFailure;
                        if (! (stat = theImage_YN.readFromFile(ynTexName)) )    return MS::kFailure;
                        if (! (stat = theImage_ZP.readFromFile(zpTexName)) )    return MS::kFailure;
                        if (! (stat = theImage_ZN.readFromFile(znTexName)) )    return MS::kFailure;

                        // Only create texture names the first time
                        if (fTextureName == -1)         glGenTextures(1, &fTextureName);

                        glBindTexture( GL_TEXTURE_CUBE_MAP_ARB, fTextureName );
                        glEnable( GL_TEXTURE_CUBE_MAP_ARB );

                        // The cubeMap textures have to have the same size
                        //
                        unsigned int width, height;
                        stat = theImage_XP.getSize( width, height );

                        glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X_ARB,
                                0, GL_RGBA8, width,     height, 0, GL_RGBA,     GL_UNSIGNED_BYTE, theImage_XP.pixels() );
                        glTexImage2D(GL_TEXTURE_CUBE_MAP_NEGATIVE_X_ARB,
                                0, GL_RGBA8, width,     height, 0, GL_RGBA,     GL_UNSIGNED_BYTE, theImage_XN.pixels() );
                        glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_Y_ARB,
                                0, GL_RGBA8, width,     height, 0, GL_RGBA,     GL_UNSIGNED_BYTE, theImage_YP.pixels() );
                        glTexImage2D(GL_TEXTURE_CUBE_MAP_NEGATIVE_Y_ARB,
                                0, GL_RGBA8, width,     height, 0, GL_RGBA,     GL_UNSIGNED_BYTE, theImage_YN.pixels() );
                        glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_Z_ARB,
                                0, GL_RGBA8, width,     height, 0, GL_RGBA,     GL_UNSIGNED_BYTE, theImage_ZP.pixels() );
                        glTexImage2D(GL_TEXTURE_CUBE_MAP_NEGATIVE_Z_ARB,
                                0, GL_RGBA8, width,     height, 0, GL_RGBA,     GL_UNSIGNED_BYTE, theImage_ZN.pixels() );

                        glTexParameteri(GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
                        glTexParameteri(GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
                        glTexParameteri(GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
                        glTexParameteri(GL_TEXTURE_CUBE_MAP_EXT, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
                        glTexParameteri(GL_TEXTURE_CUBE_MAP_EXT, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
                        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);

                        for (i=0; i<6; i++)             currentTextureNames[i] = decalNames[i];
                }

                // stage 0 -- cubeMap texture for the refraction
                //
                glActiveTextureARB( GL_TEXTURE0_ARB );
                glBindTexture( GL_TEXTURE_CUBE_MAP_ARB, fTextureName );
                glEnable( GL_TEXTURE_CUBE_MAP_ARB );

                // stage 1 -- cubeMap texture for the reflection
                //
                glActiveTextureARB( GL_TEXTURE1_ARB );
                glBindTexture( GL_TEXTURE_CUBE_MAP_ARB, fTextureName );
                glEnable( GL_TEXTURE_CUBE_MAP_ARB );
        }
        view.endGL();

        return MS::kSuccess;
}


// Initialize the register combiners setting
//
void    hwRefractReflectShader_NV20::initCombiners(const MDrawRequest& request, M3dView& view)
{
        view.beginGL();
        {
                // Use only the 1st stage of the register combiner stages
                //
                glCombinerParameteriNV(GL_NUM_GENERAL_COMBINERS_NV, 1);

                {
                        float refractivity[4], reflectivity[4];
                        refractivity[0] = refractivity[1] = refractivity[2] = refractivity[3] = 1.0f - fReflectivity;
                        reflectivity[0] = reflectivity[1] = reflectivity[2] = reflectivity[3] = fReflectivity;

                        glCombinerParameterfvNV(GL_CONSTANT_COLOR0_NV, refractivity);
                        glCombinerParameterfvNV(GL_CONSTANT_COLOR1_NV, reflectivity);
                }
                
                // combiner 0
                // a*b+c*d
                // a is from the refractive color
                // c is from the refrlective texture
                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_CONSTANT_COLOR0_NV, GL_UNSIGNED_IDENTITY_NV, GL_RGB);
                glCombinerInputNV(GL_COMBINER0_NV, GL_RGB, GL_VARIABLE_C_NV, GL_TEXTURE1_ARB, GL_UNSIGNED_IDENTITY_NV, GL_RGB);
                glCombinerInputNV(GL_COMBINER0_NV, GL_RGB, GL_VARIABLE_D_NV, GL_CONSTANT_COLOR1_NV, GL_UNSIGNED_IDENTITY_NV, GL_RGB);
                
                // output:
                // (stage, portion, abOutput, cdOutput, sumOutput, scale, bias, abDotProduct, cdDotProduct, muxSum)
                glCombinerOutputNV(GL_COMBINER0_NV, GL_RGB, GL_DISCARD_NV, GL_DISCARD_NV, GL_SPARE0_NV, GL_NONE, GL_NONE, GL_FALSE, GL_FALSE, GL_FALSE);
                
                // final combiner
                // output: Frgb = A*B + (1-A)*C + D
                // (variable, input, mapping, componentUsage);
                // Just pass through the D variable
                //
                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_SPARE0_NV, GL_UNSIGNED_IDENTITY_NV, GL_RGB);
        }
        view.endGL();
}


// Load the textures, update the necessary variable values, initialize register combiners,
// save and load the matrices with the proper values
//
MStatus hwRefractReflectShader_NV20::preDraw(const MDrawRequest& request, M3dView& view)
{
        MStatus stat = loadTextures( request, view);

        if( MS::kSuccess != stat )              return stat;

        // get the reflectivity value
        //
        MPlug   tPlug(thisMObject(), reflectivity);
        if( tPlug.getValue( fReflectivity ) )
        {
                if( fReflectivity < 0.01f )     fReflectivity = 0.01f;
                if( fReflectivity > 1.0f )      fReflectivity = 1.0f;
        }
        else    fReflectivity = 0.5f;
        
        // get the refraction index value
        //
        MPlug   rPlug(thisMObject(), refractionIndex);
        if( rPlug.getValue( fRefractionIndex ) )
        {
                if ( fRefractionIndex < 1.0f )  fRefractionIndex = 1.0f;
                if ( fRefractionIndex > 2.0f )  fRefractionIndex = 2.0f;
        }
        else    fRefractionIndex = 1.0f;
        
        initCombiners( request, view );
        
        // Compute the camera rotation angle and axis
        //
        MDagPath        cameraPath;
        MStatus         status = view.getCamera( cameraPath );
        MMatrix         mmatrix = cameraPath.inclusiveMatrix( &status );
        MTransformationMatrix tmatrix( mmatrix );
        
        MQuaternion camRotation = tmatrix.rotation();
        MVector         camAxis;
        double          camTheta;
        camRotation.getAxisAngle(  camAxis, camTheta );
        
        // Convert to degrees from radians
        camTheta *= 57.295779513082320876798154814105;  // == (180 / M_PI)
        
        view.beginGL();
                glMatrixMode( GL_TEXTURE );
                glPushMatrix();
                glLoadIdentity();
                glScalef(1.0, -1.0, 1.0);
                glRotated( camTheta, camAxis[0], camAxis[1], camAxis[2]);
                glMatrixMode( GL_MODELVIEW );
        view.endGL();

        return stat;
}


/* virtual */
MStatus hwRefractReflectShader_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;

        // Save the current states of the openGL attributes
        //
        view.beginGL();
                glPushAttrib( GL_ALL_ATTRIB_BITS );
                glPushClientAttrib(GL_CLIENT_VERTEX_ARRAY_BIT);
        view.endGL();

        MStatus preDrawStatus = preDraw( request, view );

        if( MS::kSuccess == preDrawStatus )
        {       
                loadVertexProgramGL( view );
                
                view.beginGL();
                {
                        glEnable(GL_REGISTER_COMBINERS_NV);
                        //
                        // Load, bind and enable the vertex program
                        //
                        glBindProgramNV(GL_VERTEX_PROGRAM_NV, vertex_program_id);
                        glEnable(GL_VERTEX_PROGRAM_NV);
                        {                               
                                // VERTEX REGISTERS (Attributes):
                                // 0 - coord
                                // 2 - normal
                                //
                                glVertexAttribPointerNV( 0, 3, GL_FLOAT, 0, vertexArray );
                                glVertexAttribPointerNV( 2, 3, GL_FLOAT, 0, normalArrays[0] );
                                
                                glEnableClientState( GL_VERTEX_ATTRIB_ARRAY0_NV );
                                glEnableClientState( GL_VERTEX_ATTRIB_ARRAY2_NV );
                                
                                glDrawElements(GL_TRIANGLES, indexCount, GL_UNSIGNED_INT, indexArray);
                                
                                glDisableClientState( GL_VERTEX_ATTRIB_ARRAY0_NV );
                                glDisableClientState( GL_VERTEX_ATTRIB_ARRAY2_NV );
                        }
                        glDisable(GL_VERTEX_PROGRAM_NV);
                        //
                        glDisable(GL_REGISTER_COMBINERS_NV);
                }
                view.endGL();

                postDraw( request, view );
        }

        // Restore the openGL attributes
        //
        view.beginGL();
                glPopClientAttrib();
                glPopAttrib();
        view.endGL();

        return preDrawStatus;
}


// Retore the openGL matrices and the openGL texture objects states
//
MStatus hwRefractReflectShader_NV20::postDraw(
        const MDrawRequest& request,
        M3dView& view )
{
        view.beginGL();
        {
                glMatrixMode( GL_TEXTURE );
                glPopMatrix();
                glMatrixMode( GL_MODELVIEW );
                
                glActiveTextureARB( GL_TEXTURE1_ARB );
                glBindTexture( GL_TEXTURE_CUBE_MAP_ARB, 0 );
                glDisable(GL_TEXTURE_CUBE_MAP_ARB);
                
                glActiveTextureARB( GL_TEXTURE0_ARB );
                glBindTexture( GL_TEXTURE_CUBE_MAP_ARB, 0 );
                glDisable(GL_TEXTURE_CUBE_MAP_ARB);
        }
        view.endGL();

        return MS::kSuccess;
}


/* virtual */
int             hwRefractReflectShader_NV20::normalsPerVertex()
{
        return 1;
}

/* virtual */
int             hwRefractReflectShader_NV20::texCoordsPerVertex()
{
        return 1;
}

// Initialize the necessary OpenGL extensions
//
void hwRefractReflectShader_NV20::init_ext(const char * ext)
{
        if(!glh_init_extension(ext))
        { cerr << "Failed to initialize " << ext << "!" << endl; exit(0); }
}


// The constructor
//
hwRefractReflectShader_NV20::hwRefractReflectShader_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");

        // Initialize the cubeMap texture names
        //
        fTextureName = -1;
        currentTextureNames[0] = "";
        currentTextureNames[1] = "";
        currentTextureNames[2] = "";
        currentTextureNames[3] = "";
        currentTextureNames[4] = "";
        currentTextureNames[5] = "";

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

        vertex_program_id = 0;          // handle for the Vertex Program
}

hwRefractReflectShader_NV20::~hwRefractReflectShader_NV20()
{
        detachSceneCallbacks();
}

void releaseVertexProgram(GLuint* pVertexProgramId)
{
        // If the vertex program id is set...
        if (*pVertexProgramId > 0)
        {
                // Unbind any vertex program...
                glBindProgramNV(GL_VERTEX_PROGRAM_NV, 0);

                glDeleteProgramsNV(1, pVertexProgramId);

                // For sanity, set the id to 0.
                *pVertexProgramId = 0;
        }
}


void hwRefractReflectShader_NV20::releaseEverything()
{
        if (fTextureName != -1) glDeleteTextures(1, &fTextureName);

        releaseVertexProgram(&vertex_program_id);

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

void hwRefractReflectShader_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 hwRefractReflectShader_NV20::releaseCallback(void* clientData)
{
        hwRefractReflectShader_NV20 *pThis = (hwRefractReflectShader_NV20*) clientData;
        pThis->releaseEverything();
}

void hwRefractReflectShader_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, "4.0", "Any");
        status = plugin.registerNode( "hwRefractReflectShader_NV20", hwRefractReflectShader_NV20::id, 
                                              hwRefractReflectShader_NV20::creator, hwRefractReflectShader_NV20::initialize,
                                                                  MPxNode::kHwShaderNode, &UserClassify );
        if (!status) {
                status.perror("registerNode");
                return status;
        }

        return MS::kSuccess;
}

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

        status = plugin.deregisterNode( hwRefractReflectShader_NV20::id );
        if (!status) {
                status.perror("deregisterNode");
                return status;
        }

        return MS::kSuccess;
}


void * hwRefractReflectShader_NV20::creator()
{
    return new hwRefractReflectShader_NV20();
}

// Initialize the plug-in. Called once when the plug-in is loaded.
// This mostly involve creating attributes.
MStatus hwRefractReflectShader_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);

    refractionIndex = nAttr.create( "refractionIndex", "ri", MFnNumericData::kFloat);
    nAttr.setStorable(true);
    nAttr.setKeyable(true);
    nAttr.setMin(1.0f);
    nAttr.setMax(2.0f);
    nAttr.setDefault(1.1f);

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

 // Add the attributes here

    addAttribute(color);
    addAttribute(refractionIndex);
    addAttribute(reflectivity);

    attributeAffects (colorR, outColor);
    attributeAffects (colorG, outColor);
    attributeAffects (colorB, outColor);
    attributeAffects (color,  outColor);

    attributeAffects (refractionIndex,   outColor);
    attributeAffects (reflectivity,   outColor);

    return MS::kSuccess;
}


// This function gets called by Maya to evaluate the texture.
// See "Writing a shading node plug-in" in the documentation
// for more information.
//
// CAVEAT: This part of the HW shader plug-in is meant to allow
// seamless transition from HW to SW rendering.
// Unfortunately, as of 4.0.1 it's somewhat flaky.
// Meanwhile, it is recommended to build two shading networks
// in parallel (one for SW, one for HW) and use MEL scripts
// to switch from one to the other.
//
MStatus hwRefractReflectShader_NV20::compute(
const MPlug&      plug,
      MDataBlock& block ) 
{ 
        // Get color and lightModel from the input block.
        // Get UV coordinates from the input block.
        
        bool k = false;
    k |= (plug==outColor);
    k |= (plug==outColorR);
    k |= (plug==outColorG);
    k |= (plug==outColorB);
    if( !k ) return MS::kUnknownParameter;

    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;
}