[Mesa-dev] [PATCH 2/2] i965: Disable Z16 in all APIs.

[Chia-I Wu]

On Mon, Apr 14, 2014 at 1:04 PM, Kenneth Graunke <kenneth at whitecape.org> wrote:
> We originally thought that GL 3.0 required GL_DEPTH_COMPONENT16 to map
> exactly to Z16.  However, we misread the specification, thanks in part
> to LaTeX reordering the tables in the PDF.
>
> Page 180 of the GL 3.0 specification (glspec30.20080923.pdf) says:
> "[...] memory allocation per texture component is assigned by the GL to
> match the allocations listed in tables 3.16-3.18 as closely as possible.
> [...]
>
> Required Texture Formats
> [...]
> In addition, implementations are required to support the following sized
> internal formats.  Requesting one of these internal formats for any
> texture type will allocate exactly the internal component sizes and
> types shown for that format in tables 3.16-3.17:"
>
> Notably, however, GL_DEPTH_COMPONENT16 does /not/ appear in table 3.16
> or table 3.17.  It appears in table 3.18, where the "exact" rule doesn't
> apply, and it falls back to the "closely as possible" rule.
>
> The confusing part is that the ordering of the tables in the PDF is:
>
> Table 3.16 (pages 182-184)
> Table 3.18 (bottom of page 184 to top of 185)
> Table 3.17 (page 185)
>
> Presumably, people saw table 3.16, then saw the table immediately
> following with DEPTH_COMPONENT* formats, and assumed it was 3.17.
>
> Based on a batch by Chia-I Wu, but without the driconf option to force
s/batch/patch/

Both patches look good to me.  Unless I overlooked your patch for
piglit, this is needed

http://lists.freedesktop.org/archives/piglit/2014-February/009650.html

to avoid a false regression.  It would be great if you could review
and commit the piglit fix, as I do not have commit access.

> Z16 to be used.  It's not required, and there's apparently no benefit
> to actually using it.
>
> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> ---
>  src/mesa/drivers/dri/i965/brw_surface_formats.c | 6 ------
>  1 file changed, 6 deletions(-)
>
> Sorry if this is a duplicate of an earlier patch...the only one I could
> find in my inbox was the one with the driconf option.
>
> diff --git a/src/mesa/drivers/dri/i965/brw_surface_formats.c b/src/mesa/drivers/dri/i965/brw_surface_formats.c
> index 196f139..5907dd9 100644
> --- a/src/mesa/drivers/dri/i965/brw_surface_formats.c
> +++ b/src/mesa/drivers/dri/i965/brw_surface_formats.c
> @@ -608,7 +608,6 @@ brw_init_surface_formats(struct brw_context *brw)
>     brw->format_supported_as_render_target[MESA_FORMAT_Z24_UNORM_S8_UINT] = true;
>     brw->format_supported_as_render_target[MESA_FORMAT_Z24_UNORM_X8_UINT] = true;
>     brw->format_supported_as_render_target[MESA_FORMAT_S_UINT8] = true;
> -   brw->format_supported_as_render_target[MESA_FORMAT_Z_UNORM16] = true;
>     brw->format_supported_as_render_target[MESA_FORMAT_Z_FLOAT32] = true;
>     brw->format_supported_as_render_target[MESA_FORMAT_Z32_FLOAT_S8X24_UINT] = true;
>
> @@ -630,12 +629,7 @@ brw_init_surface_formats(struct brw_context *brw)
>      *
>      * Other speculation is that we may be hitting increased fragment shader
>      * execution from GL_LEQUAL/GL_EQUAL depth tests at reduced precision.
> -    *
> -    * However, desktop GL 3.0+ require that you get exactly 16 bits when
> -    * asking for DEPTH_COMPONENT16, so we have to respect that.
>      */
> -   if (_mesa_is_desktop_gl(ctx))
> -      ctx->TextureFormatSupported[MESA_FORMAT_Z_UNORM16] = true;
>
>     /* On hardware that lacks support for ETC1, we map ETC1 to RGBX
>      * during glCompressedTexImage2D(). See intel_mipmap_tree::wraps_etc1.
> --
> 1.9.2
>
> _______________________________________________
> mesa-dev mailing list
> mesa-dev at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/mesa-dev



-- 
olv at LunarG.com