Hello Christoph, Christoph John wrote: > Hey Daniel, > thanks I just found the tutorial. But I remembered that the OpenSG tutorial > stated somewhere that ray intersection performs quite weak in presence of > larger geometry. It says it should not be used for collision detection and > things like that as it checks for ray intersection on each object (polygon? > have not checked the source yet). > Therefore I was interested if there is a faster way to get to the polygon > like color picking. > There is an tutorial which uses this technique for fast object picking but > not for single polygons. I assume I have to implement it myself :(
right, the color picking tutorial (Tutorials/30ID_Buffer.cpp) works on the object level not the polygon level. The IntersectAction uses the bounding boxes of the objects in the scene to determine which object(s) are hit, then goes through all polygons to distinguish close objects and get the hit point and normal etc. This last part is what makes the operation somewhat slow, as the OpenSG data structures are optimized for fast rendering not fast intersection tests. However, I would not expect color picking on the level of individual polygons to be very fast either, as that requires a state change for each polygon which slows the rendering pipeline down. If you are interested in collision detected, take a look at the CollDet library (<http://cg.in.tu-clausthal.de/research/colldet/>). Hope it helps, Carsten ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Opensg-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/opensg-users
