On Mon, 2010-12-13 at 18:55 +0000, Tomas Frydrych wrote: > > * Make the Window actor (a custom actor) munge the x/y coordinates > > when painting with Cogl so after the perspective transform the x/y > > coordinates are the same independent of Z. > > IIRC the depth test is quite sensitive; even if the z coordinate in the > window stack varies by as little as 0.05 pixel this should be enough to > reduce the overdraw, but the difference should not have any real impact > on the appearance of the windows in the x,y plane even with a stack of 8 > windows or so.
Yeah, based on the formulas in: http://www.opengl.org/resources/faq/technical/depthbuffer.htm#dept0045 I calculate that for a 24-bit depth buffer, the precision around the z=0 location of the stage is somewhat better than 1e-6. You probably wouldn't want to use that amount of separation since float round-off could collapse windows but stacking 10 or 20 windows with a separation of 1e-5 is probably fine. Worth experimenting with anyways compared to more complex techniques. - Owen _______________________________________________ clutter-app-devel-list mailing list [email protected] http://lists.clutter-project.org/listinfo/clutter-app-devel-list
