Sorry, my bad. I didn't understand how Apple's gcc interacts with
system frameworks (looks like I'm still a Unix guy ...), that's why I
thought we'd have to use the include files from X11 (but then link
against the framework libraries).
Apparently, gcc automatically locates header files in the system
frameworks if the #include in C specifies a subdirectory that has the
same name as the system framework. That's why we need
#include <GLUT/glut.h>
instead of <GL/glut.h> to build directly with the GLUT framework. For
OpenGL, the framework is called OpenGL, so we need includes
#include <OpenGL/gl.h>
#include <OpenGL/glu.h>
instead of <GL/gl.h> and <GL/glu.h>. These includes are nicely
encapsulated in the module's source code, so this would be a fairly
easy change (I suggest using an #ifdef HAVE_AGL_GLUT, because that
indicates we're building the AGL interface).
However, there are a few drawbacks:
1. Everything breaks down because of zillions of conflicting
definitions. Almost everything in "glext_procs.h" is also defined in
Apple's <OpenGL/gl.h> (but doesn't seem to be in the X11 <GL/gl.h>
header); a notable exception is the GLAPI macro. Also, various
functions like glUniformMatrix2x3fv() (from "gl_util.h") are also
defined in <OpenGL/gl.h>.
2. This only works as long as people use the standard Perl and GCC
that come with Mac OS X. Antonio said he'd built his own Perl, and
there's a chance he picked up a gcc installed with Fink, which won't
automatically include the system frameworks (I think).
I suspect that problem 1 can be fixed, but it will probably take some
patience and a few rounds of trial and error. I don't understand
enough about OpenGL to know where all these macros and functions
should be declared.
When trying to track down the header files, I got very confused
because the Perl build seemed to be picking up a <GL/gl.h> that it
shouldn't be able to see. It turned out that ON EVERY PLATFORM EXCEPT
WINDOWS, the local file "include/GL/gl.h" is used instead of the
system headers, by the following code on lines 16 .. 21 of "gl_util.h":
> /* Provide GL header files for Windows */
> #define INCLUDE_LOCAL_HEADER !defined(HAVE_W32API)
> #if INCLUDE_LOCAL_HEADER
> #include "./include/GL/gl.h"
> #else
> #include <GL/gl.h>
> #endif
I can't believe this is intentional, as it does the exact opposite of
what the comment says. The strange thing is that the module builds
correctly without X11 if we include <OpenGL/glu.h> and <GLUT/glut.h>
from the frameworks, but use local "include/GL/gl.h" instead of the
system header. But isn't that inviting disaster? Can you be sure
that this local header file is compatible with the actual OpenGL
libraries?
Rather confusedly,
Stefan
PS: I'll send a patch for the messy version (GLU and GLUT from
frameworks, local gl.h header) off list. It compiles and passes all
tests on my machine, but I'm still worried about not using a system
header file!
>
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