[Mesa-dev] [PATCH] mesa: fix tex format selection for GL_R32F and other R/G float formats

[Jose Fonseca]

----- Original Message -----
> The i965 driver advertises GL_ARB_texture_float and GL_ARB_texture_rg
> support but the ctx->TextureFormatSupported[] table entries for
> MESA_FORMAT_R_FLOAT32 and MESA_FORMAT_RGBA_FLOAT32 are false on gen 4
> hardware.  So the case for GL_R32F would fail and we'd print an
> implementation error.
> 
> This patch adds more Mesa tex format options for GL_R32F and other
> R/G
> formats so we fall back to 16-bit formats when 32-bit formats aren't
> available.
> 
> Eric made the same fix in commit 6216a5b4 for the non R/G formats.
> 
> This should fix https://bugs.freedesktop.org/show_bug.cgi?id=44039
> 
> NOTE: This is a candidate for the 8.0 branch.
> ---
>  src/mesa/main/texformat.c |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/src/mesa/main/texformat.c b/src/mesa/main/texformat.c
> index 7e60541..2f680d9 100644
> --- a/src/mesa/main/texformat.c
> +++ b/src/mesa/main/texformat.c
> @@ -788,19 +788,25 @@ _mesa_choose_tex_format( struct gl_context
> *ctx, GLint internalFormat,
>  	 RETURN_IF_SUPPORTED(MESA_FORMAT_R_FLOAT16);
>  	 RETURN_IF_SUPPORTED(MESA_FORMAT_R_FLOAT32);

Since we're touching this code, I think that MESA_FORMAT_RG_FLOAT(16|32) should be attempted here before MESA_FORMAT_RGBA_FLOAT(16|32), as it takes half the memory / bandwidth.

>  	 RETURN_IF_SUPPORTED(MESA_FORMAT_RGBA_FLOAT32);
> +	 RETURN_IF_SUPPORTED(MESA_FORMAT_RGBA_FLOAT16);

I think that MESA_FORMAT_RGBA_FLOAT16 should be attempted before MESA_FORMAT_RGBA_FLOAT32 for GL_*16F formats, and not after, as it is both more accurate & efficient.

>  	 break;
>        case GL_R32F:
>  	 RETURN_IF_SUPPORTED(MESA_FORMAT_R_FLOAT32);
>  	 RETURN_IF_SUPPORTED(MESA_FORMAT_RGBA_FLOAT32);

Ditto (try RG before RGBA)

> +	 RETURN_IF_SUPPORTED(MESA_FORMAT_R_FLOAT16);
> +	 RETURN_IF_SUPPORTED(MESA_FORMAT_RGBA_FLOAT16);
>  	 break;
>        case GL_RG16F:
>  	 RETURN_IF_SUPPORTED(MESA_FORMAT_RG_FLOAT16);
>  	 RETURN_IF_SUPPORTED(MESA_FORMAT_RG_FLOAT32);
>  	 RETURN_IF_SUPPORTED(MESA_FORMAT_RGBA_FLOAT32);
> +	 RETURN_IF_SUPPORTED(MESA_FORMAT_RGBA_FLOAT16);

Ditto (insert FLOAT16 before  FLOAT32).

>  	 break;
>        case GL_RG32F:
>  	 RETURN_IF_SUPPORTED(MESA_FORMAT_RG_FLOAT32);
>  	 RETURN_IF_SUPPORTED(MESA_FORMAT_RGBA_FLOAT32);
> +	 RETURN_IF_SUPPORTED(MESA_FORMAT_RG_FLOAT16);
> +	 RETURN_IF_SUPPORTED(MESA_FORMAT_RGBA_FLOAT16);
>  	 break;
>  
>        default:

Otherwise looks good. Good find.

Jose