I want to draw a surface and I need to set bounds of a 3D surface I'm drawing (using BoundingBox, BoundingSphere, BoundinLeaf or something else) because I'm working with infinite surface (in some cases I devide with number that is very close to 0). Computer automaticly sets bounds, but I need something else (for example only cube with diagonal points (-6,-6,-6) and (6,6,6). Any suggestion are welcome. Thanks!