>-- Messaggio originale -- >Date: Thu, 29 Apr 2004 10:19:08 -0700 >From: Andy Ross <[EMAIL PROTECTED]> >To: FlightGear developers discussions <[EMAIL PROTECTED]> >Subject: Re: [Flightgear-devel] YASIM question (for Andy Ross) >Reply-To: FlightGear developers discussions <[EMAIL PROTECTED]> > > >Marco Gugel wrote: >> My idea is to develop a truck simulation inside FlightGear and I >> have thought to start from Yasim because it uses the rigidbody >> dynamics; > >Right. That's the RigidBody/Integrator/BodyEnvironment >implementation. You set masses on the body, calculate forces inside >the environment, and let the integrator figure out the result. > >> But there is a "little" problem: the collision detection, which is >> not implemented. Moreover the airplanes on the gorund don't follow >> the slope of the terrain in a realistic manner: [...] is this >> behavior due to the fact that the only point of reference is the cg >> of the aircraft and not the position of the wheels? > >This is a different problem, and not the only one you are going to >discover. Indeed, the collision detection is a hack right now, which >presumes a horizontal ground plane under the aircraft. This works >just fine for airfields, but not so well for hills (or ships/carriers, >for that matter). > >It's not related to c.g. or positioning issues at all; in fact the >application of force at the position of the wheels *is* modelled >correctly in YASim, and the c.g. is computed dynamically from the mass >distribution; it isn't a "user visible" parameter... All (heh) that >is required to fix this bug is for the gear model to calculate a >proper intersection with the terrain polygons instead of using a >ground plane defined for the whole aircraft.
Is this solution reasonable to implement or is it too difficult? It's only a week that I study FlightGear code and now I don't know if this modify is easy or not to do? >A more serious problem, though, is that the current YASim gear force >model works rather poorly for ground vehicles. It "slips" against >side forces instead of holding position. See recent posts about the >gear model for more notes. A few ideas have been kicked around, but >all of them are kinda scary to implement. For the gear model I think I'll use a different wheel model. However, the main problem remain the collision detection (I have doubts that it could be done on flightgear): my idea is to identify collision between the truck and other aircraft/buildings on the scene, but still I don't understand how in the code the single object of the scene are loaded!! I know that the scenery is loaded in tiles dinamically using a cache method, but I have to investigate more about! _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
