[Mesa-dev] [PATCH] mesa: Don't advertise GL_OES_read_format in core profile

[Ian Romanick]

From: Ian Romanick <ian.d.romanick at intel.com>

OpenGL ES implementations are not allowed to ship ARB extensions, and
OpenGL implementations are not allowed to ship OES extensions.

The functionality is also included in GL_ARB_ES2_compatibility.  Ever
OpenGL core-profile driver currently exposes both extensions.  I don't
know of any applications that explicitly check for GL_OES_read_format,
so removing it seems very unlikely to cause problems.  No functionality
is removed.

I have left this extension in place for compatibility profile.  There
are still OpenGL 1.x drivers in Mesa, and adding code to check for
compatibility profile and not GL_ARB_ES2_compatibility for
GL_IMPLEMENTATION_COLOR_READ_TYPE and GL_IMPLEMENTATION_COLOR_READ_FORMAT
just feels dumb.

Three other other alternatives considered:

 - Remove the string from compatibility profile drivers but leave the
   functionality in place.

 - Add a flag to expose the extension string, and set it in every OpenGL
   driver that does not expose GL_ARB_ES2_compatibility (and those
   drivers only).  I tried this.  You can't have two instances of an
   extension in the extension table (one dummy_true for ES1 and one with
   a flag for compatibility profile), so the implementation requires a
   bit of effort.

 - Only expose the extension in compatibility if the version is less
   than 2.0.  I didn't see an easy way to do this.

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
Cc: mesa-stable at lists.freedesktop.org
---
 src/mesa/main/extensions_table.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/mesa/main/extensions_table.h b/src/mesa/main/extensions_table.h
index 91918c2..b12a9af 100644
--- a/src/mesa/main/extensions_table.h
+++ b/src/mesa/main/extensions_table.h
@@ -364,7 +364,7 @@ EXT(OES_point_size_array                    , dummy_true
 EXT(OES_point_sprite                        , ARB_point_sprite                       ,  x ,  x , ES1,  x , 2004)
 EXT(OES_primitive_bounding_box              , OES_primitive_bounding_box             ,  x ,  x ,  x ,  31, 2014)
 EXT(OES_query_matrix                        , dummy_true                             ,  x ,  x , ES1,  x , 2003)
-EXT(OES_read_format                         , dummy_true                             , GLL, GLC, ES1,  x , 2003)
+EXT(OES_read_format                         , dummy_true                             , GLL,  x , ES1,  x , 2003)
 EXT(OES_rgb8_rgba8                          , dummy_true                             ,  x ,  x , ES1, ES2, 2005)
 EXT(OES_sample_shading                      , OES_sample_variables                   ,  x ,  x ,  x ,  30, 2014)
 EXT(OES_sample_variables                    , OES_sample_variables                   ,  x ,  x ,  x ,  30, 2014)
-- 
2.7.4