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Re: GL4ES: another OpenGL over OpenGLES2 emulation - some tech. info and porting progress

Subject: Re: GL4ES: another OpenGL over OpenGLES2 emulation - some tech. info and porting progress
by Hans on 2019/3/27 15:54:50

@kas1e

Sorry kas1e. This is a really weird one, and so far none of us can think of a way that our code could trigger this behaviour. I hope you'll continue to be patient just a little bit longer.

I just thought of one possible way this might happen. If the same VBO is reused for multiple quads/tri-fans but the offset/indices used get out of sync with the vertex data, then it might cause what we're seeing.** Remember how the texture in the top quad is rotated wrongly? Well, if the wrong offset/indices were used, then one or more of the vertices would be from the previous quads/tri-fans, which could cause what you see. Assuming things get further out of sync with each quad, then the later quads would get even worse.

This is just a guess, but it's as good as anything else we've thought of so far. You could test the theory by changing the order that the quads are drawn in, and seeing what effect that has.

Hans


P.S., I thought you already had access to the debug version of Warp3D Nova.


** By this I mean that the start index in glDrawArrays, or the indices passed to glDrawElements are out of line with where the vertex data is actually stored.
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