[Mesa-dev] Fwd: [PATCH] mesa: Correctly set base and max texture levels in glTexparameterf

[Ian Romanick]

On 01/02/2013 06:44 PM, Anuj Phogat wrote:
> On Wed, Jan 2, 2013 at 11:50 PM, Brian Paul <brianp at vmware.com> wrote:
>>
>> On 01/02/2013 10:39 AM, Paul Berry wrote:
>>>
>>> On 2 January 2013 07:38, Anuj Phogat <anuj.phogat at gmail.com
>>> <mailto:anuj.phogat at gmail.com>> wrote:
>>>
>>>      @@ -670,6 +668,28 @@ _mesa_TexParameterf(GLenum target, GLenum
>>>      pname, GLfloat param)
>>>                 need_update = set_tex_parameteri(ctx, texObj, pname, p);
>>>              }
>>>              break;
>>>      +   case GL_TEXTURE_BASE_LEVEL:
>>>      +   case GL_TEXTURE_MAX_LEVEL:
>>>      +      {
>>>      +         GLint p[4];
>>>      +         /* Check if param exceeds maximum value an integer can
>>>      hold */
>>>      +         if (param > 2147483647.0f) {
>>>      +            p[0] = (GLint) 2147483647.0f;
>>>      +         }
>>>      +         else if (param < 0.0f) {
>>>      +            p[0] = 0;
>>>      +        }
>>>
>>>
>>> I'm not convinced that this amount of thoroughness is necessary.
>>> There's no language in the spec (or test cases that I'm aware of) to
>>> indicate that out-of-range floats need to be translated to INT_MAX or
>>> 0.  I think it would be adequate to just do "p[0] = (int)
>>> round(param);" and just let the behaviour be undefined for
>>> out-of-range values.
>>>
> Yes, there is no such text in the spec. But gles3 conformance is testing
> this case. GTF/Source/GL3Tests/GTFTestSGISTextureLod.c in gles3
> conformance sets param=8589934592.0f using glTexParameterf() and
> expect 2147483647 when queried using glGetTexParameteriv(). if not
> handled correctly we get param=-2147483648.
> What conformance test expects is logical but not exactly follow
> the text in spec. I'm not sure if we should file a bug in conformance
> test suite.

I believe they are relying on table 3.17 (page 145, page 157 of the PDF) 
that says TEXTURE_MAX_LEVEL can be "any non-negative integer".  I would 
expect

	glGetTexParameteriv(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, &m);
	glTexParameteriv(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, m);

to always work.  If the Get call returns -2147483648, the second call 
will generate an error.

I'll submit this as a spec bug.