First and second levels are the terrain levels. Third level is for example road that should be on the terrain surface. screenshot(without z and looking at optimal direction): www25.brinkster.com/supcode/Image1.png There are problems: In many places terrain is seen over the road. Z-fight is problem since the two levels should be in the very same level. If I don''t use z-buffer I need to sort all the stuff. I use quad-tree, so it might be enought to sort quad-nodes. Are there better solutions than sorting? Sorting still doesn''t solve all problems, does it? I''v heard that stencil-buffer can be used to achieve better z-control? How to use stencil-buffer (using OpenGL)? Note that there might be multiple terrain levels all sharing corner vertices but the road doesn''t share terrain grid-vertices. Thanks.