No, that doesn't look like a problem in the model's setup...at least not as the sole reason of the problem. But it's actually impossible to tell what's going on there. Maybe some other GL setup going wrong, but it will be quite hard to find out. I would add a log output to every GL call in the Java version and then compare the trace that this produces with the same thing taken from the C# version while rendering the exact same scene. And then see, if there is a difference between the calls that these versions do. It will be quite a lot of work, I suppose, but you need some kind of reference to track this down and currently, you have none.