[Mesa-dev] [PATCH 7/9] mesa: Fill out ARB_texture_view entry points

[Courtney Goeltzenleuchter]

Okay, that makes it easier.

Should this change be conditional based on the type of context created?

Courtney


On Thu, Dec 5, 2013 at 8:52 AM, Brian Paul <brianp at vmware.com> wrote:

> 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=SrPAWBW251dxCErQJNhB0m93E9Vb62
>> KGHxK3yiRBRuU%3D%0A&s=a0c086b7a31a804e3e786118fd1771
>> b53c85717a4cf0c8dea41b60e5acd0406b>)
>>
>> 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
>
>


-- 
Courtney Goeltzenleuchter
LunarG
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