EDIT: I took FBOs out of the equation to make sure the problem wasn't coming from there, so now I am just doing the following:
setup texture:
GLuint FB0Texture;
glGenTextures(1, &FB0Texture);
glBindTexture(GL_TEXTURE_2D, FB0Texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_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_DEPTH_COMPONENT16, size.width, size.height,
0, GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE, 0);
and then to render:
[self drawScene];
[(EAGLView *)self.view bindFB0];
glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, 320, 480);
[self drawFullScreenQuad]; (it's actually not full screen so I can see both the 3d scene and the resulting texture)
and I get the same results! Black texture if I setup FB0Texture as a "DEPTH_COMPONENT" texture, but normal scene if I setup FB0Texture as a regular GL_RGBA texture...
So I guess I am either setting up the depth texture wrong, or is it possible I am doing something wrong in the rendering which would result in the RGBA texture looking normal but the depth texture being screwed? GL_DEPTH_TEST is enabled and working fine (models look correct) so I think there is nothing wrong with the actual rendering, but at this point I am desperate for clues ...
Please help!
// END OF EDIT
I am trying to implement some basic shadow mapping on iphone, but I am stuck at rendering the depth values to a texture ... This is driving me crazy, I am obviously doing something wrong but cannot figure out what it is ...
So what I am doing :
- setup default framebuffer, attach color render buffer and depth render buffer
- setup a new framebuffer (call it FB0), attach a texture to the depth component
Then when I render:
- draw scene to FB0
- switch to default framebuffer
- draw full screen quad using FB0 as a texture
And I get ... nothing! (well I get a full white texture)
If I attach the texture to the color component of FB0 instead of the depth component, everything works fine, as in I draw the scene to FB0, then use FB0 as a texture to draw a full screen quad, and I see exactly what I would see if I was drawing directly to the default framebuffer.
However when I attach the texture to the depth component, all I get is this white screen / texture.
Some code:
setup buffers:
// Create default framebuffer object.
glGenFramebuffers(1, &defaultFramebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, defaultFramebuffer);
// Create color render buffer and allocate backing store.
glGenRenderbuffers(1, &colorRenderbuffer);
glBindRenderbuffer(GL_RENDERBUFFER, colorRenderbuffer);
[context renderbufferStorage:GL_RENDERBUFFER fromDrawable:(CAEAGLLayer *)self.layer];
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, colorRenderbuffer);
// Create depth render buffer
glGenRenderbuffers(1, &depthRenderbuffer);
glBindRenderbuffer(GL_RENDERBUFFER, depthRenderbuffer);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, 320, 480);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthRenderbuffer);
// Create Depth Map Frame Buffer
glGenFramebuffers(1, &FB0);
glBindFramebuffer(GL_FRAMEBUFFER, FB0);
// Attach texture to depth component
glGenTextures(1, &FB0Texture);
glBindTexture(GL_TEXTURE_2D, FB0Texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_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_DEPTH_COMPONENT, size.width, size.height,
0, GL_DEPTH_COMPONENT, GL_UNSIGNED_SHORT, 0);
glFramebufferTexture2D(GL_FRAMEBUFFER,
GL_DEPTH_ATTACHMENT,
GL_TEXTURE_2D,
FB0Texture,
0);
If I check the status of the framebuffers after this I get no error messages, so I am assuming the buffers are created correctly.
Then in the rendering:
[(EAGLView *)self.view setFB0]; (just binds the framebuffer)
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
[self drawScene];
[(EAGLView *)self.view setFramebuffer]; (binds back the default frame buffer)
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
[(EAGLView *)self.view bindFB0Texture];
[self drawFullScreenQuad];
[(EAGLView *)self.view presentFramebuffer];
At this point I would expect to see a black and white texture with levels of gray indicating the depth, but instead I just get a solid white quad / texture.
Again, if I attach FB0Texture to GL_COLOR_ATTACHMENT0 instead of GL_DEPTH_ATTACHMENT everything works as expected, my scene gets rendered to the texture correctly. So I guess the problem is coming from how I am attaching the texture, or maybe the order in which I am doing stuff ?
