FBO_Filter.h

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#ifndef __FBO_FILTER_H
#define __FBO_FILTER_H

#include <GL/gl.h>
#include <GL/glext.h>
#include <GL/glu.h>
#include <GL/glut.h>
#include <stdio.h>
#include <assert.h>
#include <Cg/cgGL.h>

#include <openvidia/errutil.h>

class FBO_Filter {

private :
    CGprogram cgProgram;
    CGprofile cgProfile;
    CGcontext cgContext;

    GLuint fb, oTex;
    int tWidth; int tHeight;
    int previousViewportDims[4] ;
    float depth;

    CGprogram load_cgprogram(CGprofile prof, char *name) 
    {
        fprintf(stderr, "loading %s\n", name);
        return cgCreateProgramFromFile( cgContext, CG_SOURCE,
                                    name, prof, "FragmentProgram", 0);
    }

    void renderBegin() 
    {
      //since we might be operating on downsampled images, we need 
      // to reshape our current drawing area. Record the previous
      // settings first though. 
   
      glGetIntegerv(GL_VIEWPORT, previousViewportDims );

      glViewport(0, 0, (GLsizei) tWidth, (GLsizei) tHeight );
      glMatrixMode(GL_PROJECTION);
      glPushMatrix();
      glLoadIdentity();

      float scale = 1.0;
      glFrustum(0.0, 1.0/scale,  0.0/scale, 1.0/scale,   1.0/scale,   100.0);
      gluLookAt(0.0,0.0,0.0,  0.0, 0.0,  depth,   0.0,   1.0, 0.0);
      glMatrixMode(GL_MODELVIEW);
      glPushMatrix();
      glLoadIdentity();
    }

    //return the rendering state to what it was before.
    void renderEnd() 
    {
      glViewport( previousViewportDims[0], previousViewportDims[1],
                  previousViewportDims[2], previousViewportDims[3] );
      glMatrixMode(GL_PROJECTION);
      glPopMatrix();
      glMatrixMode(GL_MODELVIEW);
      glPopMatrix();
    }

    void drawQuadTex()
    {
      glBegin(GL_QUADS);

       glMultiTexCoord2fARB(GL_TEXTURE0_ARB, 0.0f, (float)tHeight);
       glVertex3f(0.0, 0.0, depth);

        glMultiTexCoord2fARB(GL_TEXTURE0_ARB, 0.0f, 0);
        glVertex3f(0.0, 1.0, depth);

        glMultiTexCoord2fARB(GL_TEXTURE0_ARB, (float)tWidth , 0);
        glVertex3f(1.0, 1.0, depth);

        glMultiTexCoord2fARB(GL_TEXTURE0_ARB, (float)tWidth , (float)tHeight);
        glVertex3f(1.0, 0.0, depth);
    
      glEnd();
    }

    void drawQuadFBT()
    {
      glBegin(GL_QUADS);

        glMultiTexCoord2fARB(GL_TEXTURE0_ARB, 0.0f, 0);
        glVertex3f(0.0, 0.0, depth);
    
        glMultiTexCoord2fARB(GL_TEXTURE0_ARB, 0.0f, (float)tHeight);
        glVertex3f(0.0, 1.0, depth);

        glMultiTexCoord2fARB(GL_TEXTURE0_ARB, (float)tWidth , (float)tHeight);
        glVertex3f(1.0, 1.0, depth);

       glMultiTexCoord2fARB(GL_TEXTURE0_ARB, (float)tWidth , 0);
       glVertex3f(1.0, 0.0, depth);

      glEnd();
    }


public :
    
    FBO_Filter( CGprofile cgp, 
                char *name, 


                GLuint outputTex, 

                 int W, 
                 int H )  
    {
        depth = -1.0;
        //Load the Cg Program.
        cgProfile = cgp;
        cgContext = cgCreateContext();
        cgProgram  = load_cgprogram(cgProfile, name );
        cgGLLoadProgram( cgProgram );

        tWidth = W; tHeight = H;

        //create the framebuffer object.
        oTex = outputTex ;
        glGenFramebuffersEXT( 1, &fb );
        glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, fb );
        glBindTexture(GL_TEXTURE_RECTANGLE_NV, oTex );
        glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT,
              GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_RECTANGLE_NV, oTex, 0);
        CHECK_FRAMEBUFFER_STATUS()
        glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
    }


    GLuint apply( GLuint iTex,    
                  bool FBOtex  )  

    {
        //XXX all this frambuffer binding is suboptimal, but will work for now.
        glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, fb );
        glBindTexture(GL_TEXTURE_RECTANGLE_NV, iTex );
        glEnable(GL_TEXTURE_RECTANGLE_NV);

        renderBegin();
        cgGLEnableProfile(cgProfile);
        cgGLBindProgram(cgProgram);
        ( FBOtex ? drawQuadFBT() : drawQuadTex() );
        cgGLDisableProfile(cgProfile);
        renderEnd();

        glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, 0);
  
        return oTex ;
    }
};

#endif

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