On 01/20/2013 09:16 PM, Kenneth Graunke wrote:
On 01/20/2013 05:49 PM, Ian Romanick wrote:
From: Ian Romanick <ian.d.roman...@intel.com>

There really isn't any point.  There is no resource savings, and we have
to do gymnastics in the driver to make it work.

There are also bad interactions with multisampling and OpenGL ES 3.0.
In ES3, a multisample-to-singlesample blit must have identical source
and destination format.  This means a multisample RGBA8 to singlesample
RGB8 (window) blit will generate an error.  Also in ES3, RGB8 is not a
renderable format.  This means that the application CANNOT make an RGB8
multisample renderbuffer.

As a result, if an application gets an RGB8 window and wants to do
multisample FBO rendering, it will probably break.

"Fixes" gles3conform
framebuffer_blit_functionality_multisampled_to_singlesampled_blit test
on RGB8 visuals.

Signed-off-by: Ian Romanick <ian.d.roman...@intel.com>
---
There are a couple alternative ways to fix this problem, but they all
involve a lot more owrk with little imaginable benefit.  We should also
add a piglit test that checks that there are no RGB8 visuals that are
marked as conformant and ES3 capable.

  src/mesa/drivers/dri/intel/intel_screen.c | 1 -
  1 file changed, 1 deletion(-)

diff --git a/src/mesa/drivers/dri/intel/intel_screen.c
b/src/mesa/drivers/dri/intel/intel_screen.c
index 347b3dd..8609572 100644
--- a/src/mesa/drivers/dri/intel/intel_screen.c
+++ b/src/mesa/drivers/dri/intel/intel_screen.c
@@ -906,7 +906,6 @@ intel_screen_make_configs(__DRIscreen *dri_screen)
  {
     static const gl_format formats[3] = {
        MESA_FORMAT_RGB565,
-      MESA_FORMAT_XRGB8888,
        MESA_FORMAT_ARGB8888
     };

You need to reduce the array size as well, or else the loop below (using
ARRAY_SIZE(formats)) will use undefined values.  I would just remove the
explicit size and let the compiler figure it out.

Yes and no. The value of the unspecified element is defined (by the C standard) to be zero... which is still probably bad. :) I'll fix that.

I agree with removing XRGB visuals.  There's no benefit at all.  Feel
free to add by R-b on Acked-by.

--Ken


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