I wrote this to learn something about writing iOS applications, and about OpenGL.
The original is here: Substrate.
Since there isn't any concept natively under iOS of blitting bitmapped 2D graphics to the screen, I had to write a custom rendering layer on top of OpenGL. (This is what Cocos2D does too, btw.)
The actual implementation approach is mildly hair-raising and more than a little hacky: I render to a texture which then gets mapped onto a quad which is lit and displayed in the viewport. I've implemented a simple antialiased line drawing algorithm and color blending.
The cracks are rendered using a thread that writes to the texture whilst another one renders the texture to the screen. This is not the best approach, since on a platform as constrained as this one, threading overhead is to be avoided. However, it resulted in the most straightforward port of the Processing code, and I thought I might want to port other Processing scripts one day. Dunno.
Perhaps this is useful to someone! If so, enjoy.
Copyright (C) 2011 by Jon Cooper
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