On 06/10/2012 11:42 PM, Eric Anholt wrote:
On Fri, 8 Jun 2012 14:31:52 -0600, Brian Paul<bri...@vmware.com> wrote:
I've now seen a couple apps that replace a whole texture image with a
glTexImage() call instead of glTexSubImage(). The later is better
because we can skip freeing/allocating texture memory.
This patch checks if the new glTexImage's format and size matches the
current image. If so, use the TexSubImage path.
This only makes sense if drivers consistently do blit uploads for
texsubimage -- otherwise, teximage (which does) is better. Right now
i965 only manages to do so for non-depth, GL_TEXTURE_2D textures,
pre-gen6. Hopefully that will get fixed now that we've got the 3d blit
code, so that wouldn't block this patch for us.
For hardware drivers, I expect this to be no change or a loss, though.
Do you have any numbers for any driver, including software?
Most apps that want to replace a whole texture image will be using
glTexSubImage() already. I've seen many apps, examples and texts that
use/recommend this approach. So it seems to me that using this path
in an infrequent/corner case shouldn't have any downside (in principle
at least).
This change lets of skip some texture state validation and memory
free/alloc so it should be a win, modulo the blit issue.
-Brian
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/mesa-dev
