On 2005 Apr 12, Claus Reinke
there are some opengl debuggers and tracers around - I'm googling for a free windows one, mac users seem to have such support provided by apple, other platforms have their own.
Claus, Thank you for the response. I haven't found one yet for XFree86 on FreeBSD. But I did do a number of more experiments. I have a couple of odd results that maybe someone can help with. Here is the strangest one (from my perspective). I've commented which objects can be drawn, and which ones crash. I can't find *any* reason for this behavior, by looking at the code. E.g., Sphere' crashes but Cone draws fine. Looking at the .../GLUT/Objects.hs, the foreign import statements are basically identical for the two functions (Cone takes one extra argument). If anyone can imagine a way that Cone would succeed but Sphere' would fail, I'm all ears. :-) A C program can call glutSolidSphere just fine. Also, I trimmed out every unneeded OpenGL-related call; if I put in the usual boilerplate of setting the projection matrix, etc., it still has the same behavior. -- cut ----------------------------------------------- import Graphics.UI.GLUT import qualified System.Environment as Env main :: IO () main = do objIndex <- getObjIndex createWindow "test" displayCallback $= display objIndex mainLoop display :: Int -> DisplayCallback display objIndex = do renderObject Solid (objects !! objIndex) flush -- comment this out, and it still crashes on 5-6,8-11 -- This is sloppy, sorry... getObjIndex :: IO Int getObjIndex = do args <- Env.getArgs return (intOfFirstArg args) where intOfFirstArg [] = 0 intOfFirstArg (a:_) = read a objects :: [Object] objects = [ Cube 1, -- 0: OK Dodecahedron, -- 1: OK Icosahedron, -- 2: OK Octahedron, -- 3: OK Tetrahedron, -- 4: OK RhombicDodecahedron, -- 5: Crash / user error (freeglut) Sphere' 1 5 5, -- 6: Crash Cone 1 1 5 5, -- 7: OK Cylinder' 1 1 5 5, -- 8: Crash / user error (freeglut) Torus 0.75 1 5 5, -- 9: Crash Teapot 1, -- 10: Crash SierpinskiSponge 1 -- 11: Crash / user error (freeglut) ] -- cut ----------------------------------------------- The "Crash / user error (freeglut)" comment means that those three objects crash with the current GLUT code, but return this error when I "#define GLUT_GET_PROC_ADDRESS_IS_BROKEN 1" in GLUT/cbits/HsGLUT.c: objs: user error (unknown GLUT call glutSolidRhombicDodecahedron, check for freeglut) There's no configure tests which define that - it's not mentioned anywhere else besides HsGLUT.c - so I don't know if that's meaningful, but I thought I would explain it. There's another class of crashes related to lighting & display lists, but this is way too long as it is. I'll stop here, and hope that someone might be able to suggest a reason for the strange behavior. Thanks a lot for reading this far! Tim -- If you're not part of the solution, you're part of the precipitate.