Hi Everybody. I rode Stan Melax interesting article dealing with Dynamic Plan Shifting( available at: http://www.cs.ualberta.ca/~melax/bsp/ ). I''m trying to test it. I found one bug with special world geometry, even if using a quite good CSG algorithm. When you have two polytopes very close then if you shift dynamicly planes, and if distance between the two polytopes is lower than the distance of your shift, then I noticed a collision bug. Maybe because we do not keep our BSP tree valid and have to recompute one.. Is that 1)my shift fonctiun is invalid, 2) my geometry remain invalid even after CSG operations or 3) this is a knwon bug of dynamic plane shift ? Is yes do you know how to compute a BSP tree with offset value ? Thank You, -- Julien Meyer www.jadeware.org