Original Post
Hello! I''ve been doing a 3D tile based map viewer recently. The view is isometric. I generate a bounding box for each tile, and then before rendering one tile, I check if its bounding box is visible (I don''t render it when it is not visible). I do this by checking the visibility of the box''s corners (with gluProject). This works fine when at least one corner is visible. But in some cases none of the corners are visible but the box is still visible because an edge of the box is visible (this happens mainly at the screen corners). So my question is how can I make a fast visibility test that works in any case?