[cl-opengl-devel] problem with vertex arrays

[Bart Botta]

On Wed, Sep 10, 2008 at 6:55 AM, Sebastian Berchtold
<Stoned-Jonny at gmx.net> wrote:
> This leads me to the following questions:
> Whats the difference between the "%gl:" und the "gl" package?   it spent some time on it but didnt get it

%gl: is for the C level bindings, which take exactly the arguments the
C functions take, so you need to pass C pointers where expected
instead of lisp data structures, and uses specific data types, etc.
%gl is mostly autogenerated, so has everything C has.

gl: is the lisp side of the API, which uses lisp data structures, and
handles (some) data type translations for you, etc. but is hand
written, so less complete.

%gl is mainly for implementing the gl package, but is also available
for implementing higher level abstractions when going through gl would
be inefficient.

> Does anybody know how to fix that?^^
implement gl:vertex-pointer, or allocate a C array using cffi, store
the vertices in it, and pass that to %gl:vertex-pointer (make sure to
deal with memory management, etc. properly by hand in that case, since
GC can't deal with it for you)

> Does this example run on somebody elses machine?
Probably not, which is probably why it isn't loaded by default :)
Those APIs are sort of hard to wrap nicely, since they may need to
keep pointers around, and that sort of thing, so they aren't quite
done yet.
I think there is an example of the current code for that in
examples/misc/opengl-array.lisp.

--
b