Here, totally free for everyone, is my current graphics engine and sample game project using VBOs, shaders, and even post processing.* It has a material system as well.* My goal is to make this demo run as fast as possible and remove or change any code that is not correct. It uses GL ES 2.0 exclusively.
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Download my project here: http://www.mediafire.com/file/5cswgi2z8 ... Engine.zip
It's 70mb but it should download pretty quick.
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It should run on all devices 3GS and up.
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Can you help me with these few things?
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1) Why can't I remove the clear command on line 3218 of ES2Renderer.m in the classes, graphics folder of the project?* Removing it causes artifacts on the simulator and a black screen on the iPhone 4.
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2) Is there anything you can see wrong with the code in general that can be fixed? (see the setRenderTarget, createRenderTarget, and other functions)
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3) Is there anything that can be done to the project in general to make it run faster?
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Currently, without render to texture and post processing I get about 38 FPS but with it I get about 28... a 10 FPS loss!

I'd like to be able to run with at least 2 post processes at a solid 30 FPS if possible.
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What do you get out of helping me?* You get free code that the whole internet can examine, share, and learn from!* Maybe other people will be able to avoid common mistakes by the responses to this thread.
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I have spent many hours on this completely on my own and now I'm ready for some real input.
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Thanks, guys!