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Re: FBO+GLSL write to texture with less than 4 components

Subject: Re: FBO+GLSL write to texture with less than 4 components
From: Mark <email@hidden>
Date: Thu, 29 Nov 2007 16:38:43 +0100
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Am Donnerstag, 29. November 2007 13:41:09 schrieb Mark:
On 29.11.2007, at 13:35, Stefan Dösinger wrote:
The reason I really want to have the information on a 1 (or 2)
component texture is I will be reading it back to the CPU, so
avoiding
the 3 (or 2) extra components will make the readback a lot faster.
You can just read back single channels, e.g. GL_RED or GL_ALPHA
Oh, so simple it didn't come to my mind. Can this be done together
with PBO's?
I see no reason why it would fail, but the question is how the driver handles this. It might be a non 1:1 copy, so the driver might fall back to downloading everything to the CPU anyway. I guess this needs some benchmarking

Thanks for the help Stefan, I think I'll work around it using an ARGB texture and PBO one forth the size of the original texture and effectively "pack" my one component information into the destination 4 components, swizzling as needed so all looks right when back to main memory... guess that's the easiest way.

Mark _______________________________________________
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Follow-Ups:
- Re: FBO+GLSL write to texture with less than 4 components
  - From: Stefan Dösinger <email@hidden>

References:
	>FBO+GLSL write to texture with less than 4 components (From: Mark <email@hidden>)
	>Re: FBO+GLSL write to texture with less than 4 components (From: Stefan Dösinger <email@hidden>)
	>Re: FBO+GLSL write to texture with less than 4 components (From: Mark <email@hidden>)
	>Re: FBO+GLSL write to texture with less than 4 components (From: Stefan Dösinger <email@hidden>)

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