[ mesa3d-Bugs-834673 ] GL.h: functions assigned to wrong extensions

Bugs item #834673, was opened at 2003-11-02 19:26
Message generated for change (Comment added) made by elf-stone
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=100003&aid=834673&group_id=3

Category: mesa-core
Group: other
Status: Open
Resolution: None
Priority: 5
Submitted By: Ben Woodhouse (elf-stone)
Assigned to: Nobody/Anonymous (nobody)
Summary: GL.h: functions assigned to wrong extensions

Initial Comment:
The GL.h file included in mesa 5.0.2 has a number of
bugs which are causing my extension loading library not
to work with mesa's headers. 

These problems are due to the fact that a number of
extension functions are defined as being part of the
wrong extensions. 

The bugs are as follows:
- glCopyTexSubImage3DEXT is part of
GL_EXT_copy_texture, not GL_EXT_texture3D (line 2189)

- glColorSubTableEXT is part of GL_EXT_color_subtable,
not GL_EXT_paletted_texture (line 2394)

- glPointParameterfvSGIS and glPointParameterfSGIS are
part of GL_SGIS_point_parameters, not
GL_EXT_point_parameters (lines 2362, 2363)

This can be verified by looking at the official
extension specs at
http://oss.sgi.com/projects/ogl-sample/registry/

----------------------------------------------------------------------

>Comment By: Ben Woodhouse (elf-stone)
Date: 2003-11-03 20:14

Message:
Logged In: YES 
user_id=900284

The library I'm writing is a cross-platform extension
loading library based on glext.h. It defines function
pointers for all extensions listed in glext.h, and provides
automatic linking for every extension function. It is
designed to replace glext.h. 

In the header file, I'm including GL.h, with GL_GLEXT_LEGACY
defined to avoid the inclusion of glext.h. The header then
defines function pointers and typedefs for every extension
not already defined in the gl.h, using #ifndef blocks. In
this way, the extensions already defined in mesa's gl.h are
ignored in the build.

The problem arises because in some cases the functions
defined in Mesa's gl.h are assigned to different extensions
to those defined in glext.h (upon which my library is based)

As an example:
Mesa's gl.h doesn't define the EXT_copy_texture extension,
so in my header, the function pointers associated with the
extension are declared. But mesa has already declared
glCopyTexSubImage3DEXT as a different type (in the
EXT_texture3D definition), so a conflict occurs. 

I realise I can define __gl_ext_h in my file to activate the
include guard on the glext.h file, and this may achieve what
I need more effectively. This seemed like a nasty hack though. 

The alternative would be to write some special-case code to
make the library compatible with mesa, but since the header
is currently ~6000 lines and automatically generated, this
is easier said than done.

----------------------------------------------------------------------

Comment By: Ian Romanick (idr)
Date: 2003-11-03 19:18

Message:
Logged In: YES 
user_id=423974

This is a bit tricky.  glCopyTexSubImage3DEXT is part of
EXT_copy_texture, but it is only defined if EXT_texture3D is
also defined.  glColorSubTableEXT is part of *both* those
extensions.  I'm not sure why EXT_point_parameters has both
the SGIS and the EXT versions of the functions, but I assume
it was as a convenience.

What are you trying to accomplish?  Unless you explicitly
define GL_GLEXT_LEGACY (which you probably shouldn't do),
you won't even see those definitions.  The definitions in
glext.h are the official cannonized defines.  You'll be
*much* better off to use that instead.  If GL_GLEXT_LEGACY
is not defined, glext.h will automatically be included.

But again, what are you trying to accomlish?  Maybe we need
to meet in the middle somewhere.

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=100003&aid=834673&group_id=3

-------------------------------------------------------
This SF.net email is sponsored by: SF.net Giveback Program.
Does SourceForge.net help you be more productive?  Does it
help you create better code?   SHARE THE LOVE, and help us help
YOU!  Click Here: http://sourceforge.net/donate/