[Mesa-dev] [PATCH] mesa: implement glTexImage as glTexSubImage when possible

[Eric Anholt]

On Fri,  8 Jun 2012 14:31:52 -0600, Brian Paul <brianp at 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?
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