GL_APPLE_shader _framebuffer_fetch

PowerVR Insider
1
Hi, I saw at https://developer.apple.com/videos/wwdc/2012/?id=513 that iOS6 devices will support a new GL extension GL_APPLE_shader_framebuffer_fetch for programmable blending. I've been thinking about this is for a bit and now I think this is a really cool extension. Thanks to Imagination for providing this feature! (Apparently the hardware supports this for a long time already.)

My question is: does this extension show a similar performance as usual (non-commutative) blending on PowerVR GPUs?

Thanks


2

Hi Martin,

Both options should be comparable as they both should access the on-chip colour buffer directly, but blending operations written in your own shaders may be affected by precision conversions, how they are interpreted by the shader compiler and, of course, human error.

Thanks,
Joe