I'm trying to track the cause of 'jagged edges' on a primitive. My application can render a surface primitive or a solid primitive (using the Parasolids kernel). When I render a surface, for example, a cylinder, it looks fine. If I render a solid cylinder, I get jagged edges. When I rotate the solid cylinder, the edges smoothe out and disappear when I've rotated it so I'm looking directly down on it. It almost appears to be a problem with lighting or shadows. Eventhough I can make out the boundary of the solid, the triangles at the edge appear to be in the 'dark'. Anyone have an idea what's casuing this?

Sounds like Z-buffering.. shouldn't be if I understand the scenario... but jagged edges are (always?) the cause of Z-buffer when the precision gets too low.

It could be a couple different things, depending on the serverity of jaggedness. Like Syranide suggested, it could be a z-buffer error. Could you post your projection matrix code? This is usually a source of z-buffer errors.

It could also be an aliasing issue, but the jaggies are usually a lot less noticable if this is the case.