| Re: [AD] Memory Bitmap to Display blit slow? |
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- To: Coordination of admins/developers of the game programming library Allegro <alleg-developers@xxxxxxxxxx>
- Subject: Re: [AD] Memory Bitmap to Display blit slow?
- From: Evert Glebbeek <eglebbk@xxxxxxxxxx>
- Date: Sun, 1 Mar 2009 15:17:25 -0800
On 1 mrt 2009, at 14:44, Stefanos A. wrote:
Some recent posts on GameDev (or was it Beyond3D?) indicated an
unoptimized upload speed of ~400MB/sec from system memory to OpenGL.
The
poster was able to improve speed significantly by breaking up the
updates
in smaller calls to glTexSubImage2D, presumably because a single big
call
would thrash the cache.
Weird. I would always have expected a single block copy to be faster
than multipl smaller block copies...
Which reminds me: you are using glTexSubImage2D instead of
glTexImage2D
for blitting, right? The latter allocates video memory anew and will
positively destroy performance.
Hmm. We seem to use glTexImage2D to upload a bitmap and use
glTexSubImage2D to synchronise when an image is unlocked. I can play
around with that, I suppose.
Evert