]> Hi I've sortof resolved the original problem by a) being awake, b) realising what the compiler was actually saying and c) simplifying the code to always convert to rgba32 and hence all textures will be in that format. I am still unsure how to handle the general problem of determining the type of class and passing to specific functions but it'll keep! Regards, Chris ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners