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On 07/23/2011 07:53 AM, Brian Paul wrote:
> On Sat, Jul 23, 2011 at 2:58 AM, Ian Romanick <i...@freedesktop.org> wrote:
>> From: Ian Romanick <ian.d.roman...@intel.com>
>>
>> ---
>> src/mesa/main/texcompress.c | 63
>> +++++++++++++++++++++++++++++++++++++++++++
>> src/mesa/main/texcompress.h | 3 ++
>> 2 files changed, 66 insertions(+), 0 deletions(-)
>>
>> diff --git a/src/mesa/main/texcompress.c b/src/mesa/main/texcompress.c
>> index d820ae9..4a8094f 100644
>> --- a/src/mesa/main/texcompress.c
>> +++ b/src/mesa/main/texcompress.c
>> @@ -40,6 +40,69 @@
>>
>>
>> /**
>> + * Get the GL base format of a specified GL compressed texture format
>> + *
>> + * \return
>> + * The base format of \c format if \c format is a compressed format (either
>> + * generic or specific. Otherwise 0 is returned.
>> + */
>> +GLenum
>> +_mesa_gl_compressed_format_base_format(GLenum format)
>> +{
>> + switch (format) {
>> + case GL_COMPRESSED_RGB:
>> + case GL_COMPRESSED_SRGB:
>> + case GL_COMPRESSED_RED:
>> + case GL_COMPRESSED_RG:
>> + case GL_COMPRESSED_RED_RGTC1:
>> + case GL_COMPRESSED_SIGNED_RED_RGTC1:
>> + case GL_COMPRESSED_RG_RGTC2:
>> + case GL_COMPRESSED_SIGNED_RG_RGTC2:
>> + case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
>> + case GL_COMPRESSED_RGB_FXT1_3DFX:
>> + case GL_COMPRESSED_SRGB_S3TC_DXT1_EXT:
>> + return GL_RGB;
>
> I think these cases need to be split up to return GL_RED and GL_RG
> base formats. The GL_ARB texture_rg extension defines those base
> formats so I'd assume that the glGetTexLevel query should return them
Arg.
The GL_ARB_texture_rg spec says:
(Add the following to Table 3.17: "Generic and specific compressed
internal formats")
Compressed Internal Format Base Internal Format Type
-------------------------- -------------------- ---------
COMPRESSED_RED RED Generic
COMPRESSED_RG RG Generic
But, the GL_ARB_texture_compression_rgtc spec says:
Add to Table 3.17 (page 155): Specific compressed internal formats
Compressed Internal Format Base Internal Format
--------------------------------- --------------------
COMPRESSED_RED_RGTC1 RGB
COMPRESSED_SIGNED_RED_RGTC1 RGB
COMPRESSED_RG_RGTC2 RGB
COMPRESSED_SIGNED_RG_RGTC2 RGB
Some consistency would have been great. I used the
GL_ARB_texture_compression_rgtc spec when I wrote the code and the
piglit test case.
The OpenGL 3.3 spec uses RED and RG for the specific compressed formats.
I'll file a bug against the GL_ARB_texture_compression_rgtc spec (since
it doesn't match the 3.x core spec), and I'll update the patch.
> too. Though, we should probably check what other vendors do.
I tested both NVIDIA and ATI. They either return a specific compressed
format (correct if the texture was compressed), a generic compressed
format (wrong), or a sized non-compressed format (wrong). I haven't
tested Apple, so they might do the right thing.
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