I am trying to implement post-processing (blur, bloom, etc.) on the iPhone using OpenGL ES 2.0. I am running into some issues. When rendering during my second rendering step, I end up drawing a completely black quad to the screen instead of the scene (it appears that the texture data is missing) so I am wondering if the cause is using a single FBO. Is it incorrect to use a single FBO in the following fashion?

For the first pass (regular scene rendering),

• I attach a texture as COLOR_ATTACHMENT_0 and render to a texture. glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texturebuffer, 0)

For the second pass (post-processing),

• I attach the color renderbuffer to COLOR_ATTACHMENT_0 glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, colorRenderbuffer)
• Then use the texture from the first pass for rendering as a quad on the screen.