[Mesa-dev] [PATCH] mesa: fix maximum allowed proxy texture size condition

[Ian Romanick]

On 01/28/2012 04:04 AM, Jose Fonseca wrote:
>
>
> ----- Original Message -----
>> width, height parameter of glTexImage2D() includes: texture image
>> width + 2 * border (if any). So when doing the texture size check
>> in _mesa_test_proxy_teximage() width and height should not exceed
>> maximum supported size for target texture type.
>> i.e. 1<<  (ctx->Const.MaxTextureLevels - 1)
>>
>> This patch fixes Intel oglconform test case: max_values
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=44970
>>
>> Note: This is a candidate for mesa 8.0 branch.
>>
>> Signed-off-by: Anuj Phogat<anuj.phogat at gmail.com>
>> ---
>>   src/mesa/main/teximage.c |   22 +++++++++++-----------
>>   1 files changed, 11 insertions(+), 11 deletions(-)
>>
>> diff --git a/src/mesa/main/teximage.c b/src/mesa/main/teximage.c
>> index d11425d..018aca0 100644
>> --- a/src/mesa/main/teximage.c
>> +++ b/src/mesa/main/teximage.c
>> @@ -1179,7 +1179,7 @@ _mesa_test_proxy_teximage(struct gl_context
>> *ctx, GLenum target, GLint level,
>>      switch (target) {
>>      case GL_PROXY_TEXTURE_1D:
>>         maxSize = 1<<  (ctx->Const.MaxTextureLevels - 1);
>> -      if (width<  2 * border || width>  2 + maxSize)
>> +      if (width<  2 * border || width>  maxSize)
>
> Anuj,
>
> I may be missing something, but I'm still unsure about this, because this will create problems for drivers that do support borders.

AFAIK, the only desktop graphics hardware that ever supported borders is 
NVIDIA.  Their driver follows the convention (width + 2 * border) < 
maxSize, and their driver advertises a maximum size of 2^n.  I tried 
creating a proxy texture that was the full 2^n plus a border on their 
closed-source Linux driver, and it was rejected.  A proxy texture 2^n-2 
plus a border was accepted.

Based on that, I believe this patch is correct.

> Intel driver sets:
>
>     ctx->Const.StripTextureBorder = GL_TRUE
>
> So I'd expect the right expression to be
>
>          if (width<  2 * border || width>  2 * border + maxSize)
>
> and that we do one two things:
>
> - we return FALSE here if border>  0 and ctx->Const.StripTextureBorder == GL_TRUE
>
> - or we make sure that the border is striped _everywhere_, including whatever upload path that caused the segfault in bug 44970.
>
>
> Jose