I'm trying to get FBOs setup and display a simple example of them.
I'm trying to render a simple scene to a texture, and then render that texture onto a square.
FBO setup:
//
// set up FBO
//
// FBO
glGenFramebuffersEXT(1, &FramebufferObject);
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, FramebufferObject);
//glEnable (GL_TEXTURE_2D);
// texture
glGenTextures(1, &FramebufferImage);
glBindTexture(GL_TEXTURE_2D, FramebufferImage);
glTexImage2D(GL_TEXTURE_2D, 0, 3, 512, 512, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
//glDisable(GL_TEXTURE_2D);
// render buffer
glGenRenderbuffersEXT(1, &FramebufferRender);
glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, FramebufferRender);
glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT, 512, 512);
glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, FramebufferRender);
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, FramebufferImage, 0);
CheckFBOStatus ();
The CheckFBOStatus returns ok.
Rendering:
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear Screen And Depth Buffer
glLoadIdentity();
GLfloat r = SoundInfo->waveform [0][1] / 255.0;
GLfloat g = SoundInfo->waveform [0][151] / 255.0;
GLfloat b = SoundInfo->waveform [0][301] / 255.0;
//
// renders this to a texture (FBO)
//
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, FramebufferObject);
glPushAttrib(GL_VIEWPORT_BIT);
glViewport(0,0,512, 512);
glTranslatef(0.0f,0.0f,-6.0f);
glBegin(GL_TRIANGLES);
glColor3f(r,0.0f,0.0f); // Set The Color To Red
glVertex3f( 0.0f, 1.0f, 0.0f); // Move Up One Unit From Center (Top Point
glColor3f(0.0f,g,0.0f); // Set The Color To Green
glVertex3f(-1.0f,-1.0f, 0.0f); // Left And Down One Unit (Bottom Left)
glColor3f(0.0f,0,b); // Set The Color To Blue
glVertex3f( 1.0f,-1.0f, 0.0f); // Right And Down One Unit (Bottom Right)
glEnd();
glPopAttrib();
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
//
// end rendering to texture
//
// now render the texture
// glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear Screen And Depth Buffer
// glLoadIdentity();
glClearColor(0.5f, 0.5f, 0.5f, 0.5f);
glTranslatef(0.0f,0.0f,-6.0f);
glRotatef (rY,0,1,0);
rY++;
glEnable(GL_TEXTURE_2D);
glBindTexture (GL_TEXTURE_2D, FramebufferImage);
glBegin(GL_QUADS);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(-3.0f, -3.0f, 0.0f);
glTexCoord2f(1.0f, 0.0f);
glVertex3f( 3.0f, -3.0f, 0.0f);
glTexCoord2f(1.0f, 1.0f);
glVertex3f( 3.0f, 3.0f, 0.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(-3.0f, 3.0f, 0.0f);
glEnd(); // Done Drawing A Quad
glDisable(GL_TEXTURE_2D);
It does render to a texture, and the texture does get rendered onto the square... But for some odd reason, it only renders the last color used to the FBO. So in this example, you only see a little bit of blue, when each corner of the triangle should have a different color.
It's hard to find examples of how to get this working right. Anyone know why it's only rendering the last color used to the FBO? Shoot, I guess I should also ask if I'm even using FBOs correctly.
-Chris
