Thread: Frame buffer not working

I am trying to render to an off-screen texture using OpenGL = for post processing effects - but the frame buffer doesn't seem to work. If I just render straight to the back buffer like normal the scene is rendered fine. But when I try to do the simplest use of frame buffers - draw to a frame buffer and then just read out of that frame buffer - I just get a black screen. This has been bugging me for hours.

So here's the setup stuff at the start of the program for the FBOs:

Code:

void init(){
// Setup GL etc....

    //Buffer textures
    glGenTextures(2, ppTexture);
	glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, ppTexture[0]);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, textureWidth, textureHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
    glBindTexture(GL_TEXTURE_2D, ppTexture[1]);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, textureWidth, textureHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);

    //Render buffer for depth buffer
    glGenRenderbuffersEXT(1, &renderbufferID);
    glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, renderbufferID);
    glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT32, textureWidth, textureHeight);

    //FBOs
    glGenFramebuffersEXT(6, framebufferID);
    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, framebufferID[0]);
    const GLenum bufs[2] = {GL_COLOR_ATTACHMENT0_EXT, GL_COLOR_ATTACHMENT1_EXT};
    glDrawBuffers(2, bufs);
    glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, renderbufferID);
    glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, ppTexture[0], 0);
    glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT1_EXT, GL_TEXTURE_2D, ppTexture[2], 0);  
}

Yes I do generate and attach a second texture, but I don't use it.

And here's the display function:

Code:

//GLUT displays the scene with this function
void display(){
    glEnable(GL_DEPTH_TEST);
    
    glBindFramebuffer(GL_FRAMEBUFFER, framebufferID[0]);
    glViewport(0,0,textureWidth, textureHeight);
    glUseProgram(GM->getShaderProgram());
    
    //Set projection
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(45, static_cast<float>(SCREEN_WIDTH) / SCREEN_HEIGHT, Z_NEAR_CLIP, Z_FAR_CLIP);
    
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    //.... draw the scene
    
    //Now read back from the frame buffer
    glUseProgram(0);
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
    glDisable(GL_LIGHTING);
    glDisable(GL_DEPTH_TEST);
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, ppTexture[0]);
    
    glClear(GL_COLOR_BUFFER_BIT);
    
    glBegin(GL_QUADS);
        glMultiTexCoord2f(GL_TEXTURE0, 0.0f, 0.0f);
        glVertex2f(-1.0f, -1.0f);
        glMultiTexCoord2f(GL_TEXTURE0, 1.0f, 0.0f);
        glVertex2f(1.0f, -1.0f);
        glMultiTexCoord2f(GL_TEXTURE0, 1.0f, 1.0f);
        glVertex2f(1.0f, 1.0f);
        glMultiTexCoord2f(GL_TEXTURE0, 0.0f, 1.0f);
        glVertex2f(-1.0f, 1.0f);            
    glEnd();
    
    //And flush
    glutSwapBuffers();
}

My shader does use glFragData[0] and glFragData[1] instead of glFragColor.

There are no OpenGL errors and the frame buffer has no error status.

Can anyone see a problem here?

I am using Windows XP and Dev-C++, old I know but I've gotten used to it and VC++ doesn't want to work for some reason.