Re: glReadPixels and glDrawPixels optimized
Re: glReadPixels and glDrawPixels optimized
- Subject: Re: glReadPixels and glDrawPixels optimized
- From: "Andy O'Meara" <email@hidden>
- Date: Wed, 13 Dec 2006 13:17:03 -0500
I'm pretty sure that glDrawPixels() doesn't have the performance and
architecture considerations compared to the usual texture upload
approach. My best recommendation is to not use glDrawPixels() at all
and instead use normal texture uploads (followed by a single quad
draw) using the GL_UNPACK_CLIENT_STORAGE_APPLE extension. Search in
ADC or this list archive (search.lists.apple.com) for it and you'll
get tons of info and sample code.
andy
On Dec 13, 2006, at 12:21 PM, Yaron Tadmor wrote:
Hi,
In order to support color profiles, I render my scene and then I
need to convert to the screen profile.
To do that I use glReadPixels to read the data, convert it using
ColorSync, and then write the pixels back using glDrawPixels.
I used GL_BGRA and GL_UNSIGNED_INT_8_8_8_8_REV since I understand
this is the best format.
The questions I have are theses:
1) When profiling I see that both glReadPixels and
glDrawPixels call glgVectorCopy<GLGProfile_Generic32, (GLGMemory)2>
(…). Does this mean openGL really only copies the pixels, or does
it convert something as well? Is what I'm doing utilizes openGL in
the best way?
2) Is there a better way to convert things to the screen
profile? I can't upload textures in the screen profile as blending
is affected by profile, so I need to let openGL blend is the
specific profile I choose (which isn't the screen profile).
Thanx
Yaron Tadmor
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