[cl-opengl-devel] playing with opengl at the repl

[Luís Oliveira]

On Sat, Jul 12, 2008 at 10:49 PM, Jose A. Ortega Ruiz <jao at gnu.org> wrote:

> what would be the best way to have an OpenGL/GLUT window open and
> manipulate it from a (non-blocked) REPL, maybe even while the GLUT main
> loop is running.

If you are using a multi-threaded Lisp, you can redefine e.g. your
glut:display method and GLUT's main loop will pick it up. Otherwise,
you'll have to interrupt the loop, redefine things, then resume it.

If you want to try GL commands at the REPL and watch their effect
interactively then try something like this:

    CL-USER> (let ((glut:*run-main-loop-after-display* nil))
               (glut:display-window (make-instance 'glut:window)))
    NIL
    CL-USER> (progn
               (gl:clear-color 1 0 0 0)
               (gl:clear :color-buffer)
               (gl:flush))

Running glut:main-loop in a separate thread seems to confuse GLUT, so
when you need GLUT's help to handle some window event, you can call
glut:main-loop-event which only handles at most one event per call,
IIUC.

HTH

-- 
Luís Oliveira
http://student.dei.uc.pt/~lmoliv/