[cl-opengl-devel] bug in render-to-texture example?

[Johann Korndoerfer]

Hi

When invoking the misc/render-to-texture.lisp example the second time
(the first time works perfectly), the whole screen flickers black
although the example runs windowed. After pressing esc, the flickering
stops but the glut window stays open. The lisp is still alive, but no
calls to gl will have any effect so i have to restart sbcl to continue
working.

This may be a bug in opengl or the graphics card driver (nvidia's in my
case) that does not surface when programming in C (creating multiple
contexts one after another is not a common use case since you restart
everything all the time).

Explicitly deleting the framebuffer, renderbuffer and texture objects
did not help. I eventually succeeded in creating a workaround as
follows: Unbind the texture after it has been drawn onto the quads, then
draw another, untextured quad (e.g. of size zero). Which does not make
any sense at all.

Does anybody have the same problems?

Johann