On 12/04/2013 03:46 PM, Courtney Goeltzenleuchter wrote:
It's come to my attention that Mesa's handling of GL_TEXTURE_BASE_LEVEL
and GL_TEXTURE_MAX_LEVEL in glTexParameter and glGetTexParameter may be
incorrect. The issue happens with the following sequence:
glTexStorage2D(GL_TEXTURE_2D, 4, GL_RGBA8, 128, 128);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 5);
glGetTexParameter(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, &n);
The key question is: What is the value of n?
Right now, the Mesa driver will clamp the glTexParameter call to the
range 0 .. 3 (as specified by the TexStorage call) and n = 3 after the
GetTexParameter call. However, the value returned on the Intel Windows
driver and NVIDIA's Linux driver return 5. This has apparently been
discussed among Kronos members in bug: 9342
(https://cvs.khronos.org/bugzilla/show_bug.cgi?id=9342
<https://urldefense.proofpoint.com/v1/url?u=https://cvs.khronos.org/bugzilla/show_bug.cgi?id%3D9342&k=oIvRg1%2BdGAgOoM1BIlLLqw%3D%3D%0A&r=lGQMzzTgII0I7jefp2FHq7WtZ%2BTLs8wadB%2BiIj9xpBY%3D%0A&m=SrPAWBW251dxCErQJNhB0m93E9Vb62KGHxK3yiRBRuU%3D%0A&s=a0c086b7a31a804e3e786118fd1771b53c85717a4cf0c8dea41b60e5acd0406b>)
which I don't have visibility of.
To match that behavior the texture object will likely need two BaseLevel
and MaxLevel attributes. One that's clamped and used locally and the
other that simply holds the set value as given by the application in the
glTexParameter call.
Thoughts?
From reading the bug report, it sounds like the ARB decided that
clamping should be done when the texture is used, not when
glTexParameter is called. In the GL 4.3 spec I don't see any language
about clamping in glTexParameter either.
We should be doing the use-time clamping already. So I think we just
have to remove the clamping step in glTexParameter.
-Brian
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/mesa-dev
