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iphoneopengl-esopengl-es-2.0post-processing

iPhone post-processing with a single FBO with Opengl ES 2.0?

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.
Solution

  • No, that FBO usage is fine. The cause is very likely to be that you didn't set the MIN/MAG filters of your texture (texturebuffer), after binding, set the GL_MIN_FILTER and GL_MAG_FILTER to GL_NEAREST or GL_LINEAR using glTexParameter, and your texture should be working.