   Wrapping objects to screen boundaries in 3D
  I'm writing a simple game demo in DirectX 9, and am looking for a method to wrap game objects (eg space ship) around the screen boundaries (ie moving past the left side of the screen brings object in on the right side).This is obviously simple in a 2D environment, but the objects are represented by 3D meshes. The game still plays like a 2D game, as in the z-values of objects do not change. The viewport is also static throughout the game.I guess what I really need is a way to determine if an object's centre has passed a screen boundary.Any ideas?   
  What I would suggesst, although it may not be the best answer, is to use a frustrum culling-esque algorithm to test whether the object is to the left of the left plane of your viewing frustrm or right of the right plane of your viewing frustrum.  To do this you're going to need extract the planes from your world, view, and projection matrices.  There's an article here on frustrum culling that has a a link to a paper on extracting the matrices you need.  The article itself then goes on to explain how to peform the required tests.  Hope this helps.-AJ   ;  Another solution which is should be really quick is to project your objects position to screen coordinates (if you're in opengl you would use gluProject) I'm not sure what direct x uses. After the position is in screen coordinates you can do a simple test between the size you have set for your screen and the position of your object.Jon   ;  First, test whether it intersects with the edge of the screen. If it doesn't, just render it normally. If it does, then render it twice, once at each side.   