Add the MESA_bgra GLES extension
This extensions adds the pairs BGRA_EXT/RGBA8 and BGR_EXT/RGB8
to the accepted combinations for format/internalformat in the
TexImage and TexSubImage calls. This is of interest in virtualized
enviornments where one wants to emulate a subset of OpenGL in a guest
that runs on a host that supports only GLES.
diff --git a/extensions/MESA/MESA_bgra.txt b/extensions/MESA/MESA_bgra.txt
new file mode 100644
index 0000000..269d04e
--- /dev/null
+++ b/extensions/MESA/MESA_bgra.txt
@@ -0,0 +1,106 @@
+Name
+
+ MESA_bgra
+
+Name Strings
+
+ GL_MESA_bgra
+
+Contact
+
+ Gert Wollny (gert.wollny 'at' collabora.com)
+
+Notice
+
+ Copyright (c) 2021 Collabora LTD
+ Copyright (c) 2009-2013 The Khronos Group Inc. Copyright terms at
+ http://www.khronos.org/registry/speccopyright.html
+
+Version
+
+ Version 1, 2021/04/30.
+ Based on EXT_bgra version 1, modified 1997/05/19.
+
+Number
+
+ OpenGL ES extension #335
+
+Dependencies
+
+ OpenGL ES 2.0 is required.
+ Written based on the wording of the OpenGL ES 3.2 specification.
+ There are interactions with the extensions EXT_clear_texture.
+
+Overview
+
+ MESA_bgra extends the list of combinations host-memory color formats
+ with internal formats to include BGRA and BGR as acceptable formats
+ with RGB8/SRGB8 and RGBA/sRGB8_ALPHA8 as internal formats respectively.
+ This feature is of interest in virtualized environments, where the host
+ supports OpenGL ES only, and the virtualized guest is supposed to support
+ a subset of OpenGL including textures created with the format BGRA.
+
+IP Status
+
+ Open-source; freely implementable.
+
+Issues
+
+ None.
+
+New Procedures and Functions
+
+ None
+
+New Tokens
+
+ Accepted by the <format> parameter of TexImage2D and TexSubImage2D:
+
+ GL_BGR_EXT 0x80E0
+ GL_BGRA_EXT 0x80E1
+
+Additions to Chapter 8 of the GLES 3.2 Specification (Textures and Samplers)
+
+ Add to table 8.2 (Pixels data formats, valid combinations of format,
+ type, and unsized internalformat).
+
+ Format Type External Internal Format
+ Bytes
+ per Pixel
+ -------------------------------------------------------------
+ BGRA UNSIGNED_BYTE 4 RGBA
+ BGR UNSIGNED_BYTE 3 RGB
+
+
+
+ Add to table 8.5 (Pixels data formats).
+
+ Format Name Elements Meaning and Order Target Buffer
+ -------------------------------------------------------------
+ BGR_EXT B, G, R Color
+ BGRA_EXT B, G, R, A Color
+
+
+ Add to table 8.9 (Effective internal format correspondig to
+ external format).
+
+ Format Type Effective
+ Internal format
+ -------------------------------------------------------------
+ BGRA_EXT UNSIGNED_BYTE RGBA8
+ BGR_EXT UNSIGNED_BYTE RGB8
+
+Interactions with EXT_clear_texture
+
+ When EXT_clear_texture is supported the accepted formats for
+ ClearTextureEXT and ClearSubTextureEXT are extended to include
+ the entries added above.
+
+
+Revision History
+
+ Original draft, revision 1.0, May 4, 2021 (Gert Wollny)
+ rewrite EXT_bgra against OpenGL ES 3.2 instead of OpenGL 1,0.
+
+ Revision 1.1 (May 5. 2021): Add the new tokens, and fix
+ Clear*Texture function names.
diff --git a/extensions/registry.py b/extensions/registry.py
index ff8d81a..4dbaa25 100644
--- a/extensions/registry.py
+++ b/extensions/registry.py
@@ -3001,6 +3001,13 @@
'supporters' : { 'MESA' },
'url' : 'extensions/MESA/GLX_MESA_copy_sub_buffer.txt',
},
+ 'GL_MESA_bgra' : {
+ 'esnumber' : 335,
+ 'flags' : { 'public' },
+ 'supporters' : { 'MESA' },
+ 'url' : 'extensions/MESA/MESA_bgra.txt',
+ },
+
'GL_MESA_framebuffer_flip_x' : {
'number' : 548,
'esnumber' : 327,
diff --git a/xml/gl.xml b/xml/gl.xml
index a61e6d7..3a2f859 100644
--- a/xml/gl.xml
+++ b/xml/gl.xml
@@ -43117,6 +43117,13 @@
<enum name="GL_TEXTURE_2D_STACK_BINDING_MESAX"/>
</require>
</extension>
+ <extension name="GL_MESA_bgra" supported="gles2">
+ <require>
+ <enum name="GL_BGR_EXT"/>
+ <enum name="GL_BGRA_EXT"/>
+ </require>
+ </extension>
+
<extension name="GL_MESA_framebuffer_flip_x" supported="gl|glcore|gles2">
<require>
<enum name="GL_FRAMEBUFFER_FLIP_X_MESA"/>
