The tesselator code uses some defines that it expects to be in the GL
headers such as GLAPI and GLAPIENTRY. These are used to mark the entry
points as exportable on each platform. We don't really want the
tesselator code to use these but we also don't want to modify the C
files so instead they are #defined to be empty in the stub glu.h. That
header is only included internally when building the tesselator/ files
so it shouldn't affect the rest of Cogl.
GLES also doesn't have a GLdouble type so we just #define this to be a
regular double.
This copies the files for the GLU tesselator from Mesa. The Mesa code
is based on the original SGI code and is released under a BSD license.
The memalloc.h header has been replaced with one that forces the code
to use g_malloc and friends. The rest of the files are not altered
from the original so it should be possible to later upgrade the files
by simply overwriting them.
There is a tesselator.h header which is expected to be included by
rest of Cogl to use the tesselator. This contains a trimmed down
version of glu.h that only includes parts that pertain to the
tesselator. There is also a stub glu.h in the GL directory which is
just provided so that the tesselator code can include <GL/gl.h>
without depending on the system header. It just redirects to
tesselator.h
