source: GTP/trunk/App/Demos/Vis/FriendlyCulling/src/DeferredShader.cpp @ 2859

#include "DeferredShader.h"
#include "FrameBufferObject.h"
#include "RenderState.h"


using namespace std;


namespace CHCDemoEngine
{


static void PrintGLerror(char *msg)
{
        GLenum errCode;
        const GLubyte *errStr;
        
        if ((errCode = glGetError()) != GL_NO_ERROR) 
        {
                errStr = gluErrorString(errCode);
                fprintf(stderr,"OpenGL ERROR: %s: %s\n", errStr, msg);
        }
}


static CGprogram sCgDeferredProgram;
static CGparameter sColorsTexParam;
static CGparameter sPositionsTexParam;
static CGparameter sNormalsTexParam;


DeferredShader::DeferredShader(int w, int h):
mWidth(w), mHeight(h)
{}


void DeferredShader::Init(CGcontext context)
{
        
        sCgDeferredProgram = 
                cgCreateProgramFromFile(context, 
                                                                CG_SOURCE,
                                                                "src/shaders/deferred.cg", 
                                                                RenderState::sCgFragmentProfile,
                                                                "main",
                                                                NULL);

        if (sCgDeferredProgram != NULL)
        {
                cgGLLoadProgram(sCgDeferredProgram);

                // we need size of texture for scaling
                sPositionsTexParam = cgGetNamedParameter(sCgDeferredProgram, "positions");  
                sColorsTexParam = cgGetNamedParameter(sCgDeferredProgram, "colors");  
                sNormalsTexParam = cgGetNamedParameter(sCgDeferredProgram, "normals"); 
        }
        else
                cerr << "deferred program failed to load" << endl;


        PrintGLerror("init");
}


void DeferredShader::Render(FrameBufferObject *fbo)
{
        GLuint positionsTex = fbo->GetColorBuffer(0)->GetTexture();
        GLuint colorsTex = fbo->GetColorBuffer(0)->GetTexture();
        GLuint normalsTex = fbo->GetColorBuffer(0)->GetTexture();

        glPushAttrib(GL_VIEWPORT_BIT);
        glViewport(0, 0, mWidth, mHeight);

        glDisable(GL_ALPHA_TEST);
        glDisable(GL_TEXTURE_2D);
        glDisable(GL_LIGHTING);
        
        glMatrixMode(GL_PROJECTION);
        glPushMatrix();
        glLoadIdentity();

        glMatrixMode(GL_MODELVIEW);
        glPushMatrix();
        glLoadIdentity();

        const float offs = 0.5f;
        
        glOrtho(-offs, offs, -offs, offs, 0, 1);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        cgGLEnableProfile(RenderState::sCgFragmentProfile);

        cgGLBindProgram(sCgDeferredProgram);

        cgGLSetTextureParameter(sColorsTexParam, colorsTex);
        cgGLEnableTextureParameter(sColorsTexParam);

        cgGLSetTextureParameter(sPositionsTexParam, positionsTex);
        cgGLEnableTextureParameter(sPositionsTexParam);

        cgGLSetTextureParameter(sNormalsTexParam, normalsTex);
        cgGLEnableTextureParameter(sNormalsTexParam);
        
        glColor3f(1.0f, 1.0f, 1.0f);

        glBegin(GL_QUADS);

        float offs2 = 0.5f;

        glTexCoord2f(0, 0); glVertex3f(-offs2, -offs2, -0.5f);
        glTexCoord2f(1, 0); glVertex3f( offs2, -offs2, -0.5f);
        glTexCoord2f(1, 1); glVertex3f( offs2,  offs2, -0.5f);
        glTexCoord2f(0, 1); glVertex3f(-offs2,  offs2, -0.5f);

        glEnd();

        cgGLDisableTextureParameter(sColorsTexParam);
        cgGLDisableTextureParameter(sPositionsTexParam);
        cgGLDisableTextureParameter(sNormalsTexParam);

        cgGLDisableProfile(RenderState::sCgFragmentProfile);
        
        glEnable(GL_LIGHTING);
        glDisable(GL_TEXTURE_2D);
        
        glMatrixMode(GL_PROJECTION);
        glPopMatrix();

        glMatrixMode(GL_MODELVIEW);
        glPopMatrix();

        glPopAttrib();

        PrintGLerror("deferred shading");
}


} // namespace