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We're developing a multiplatform game using Irrlicht engine for Mac OS X and Windows. We have actually two problems. The first problem is present on both platforms: it seems smooth groups from Maya object file don’t work in a proper way. The second one is just present on Mac OS X: it seems like some kind of Z-Buffer problem.
Smoothing groups are not supported, but .obj files can store per-vertex normals. Just export with smoothed normals and it will work as expected.
The z-buffer problem could also be a too much triangles problem. At least I don't see another surface which could trigger z-fighting. But you can test for this problem by a) getting the number of vertices of your mesh and b) changing near and far value of the camera tom something like 1;5000 (which would resolve most z-fighting artifacts). Also make sure that you don't put too many surfaces nect to each other or exactly on the same position.
It can also be (depending on the exporter) that normals/verts are getting messed. For example, in blender, you turn on HQ normals, select export normals, and turn on "Keep vert order" , often without it the meshes come out completely wacky. The vert order normally makes all the normals stable with smoothing in irrlicht as hybrid says
Last time I checked, the z-buffer on the quake example was also rather ugly if you fly up in to the sky and look down, but I didn't look into it in depth. Maybe OpenGL drivers only support a 16-bit zbuffer on the Mac. What Mac are you using?
We tried it on 3 different Macs: 2 iMac, one width ATI Radeon X1600, another width NVidia card, I guess, and on a Mac Book width Intel GMA950. The result was always the same, but under Vista and XP it was fine.
As soon as we have tried out what you’ve suggested I’ll write you about the results.
