RE: [Algorithms] Simple Air Resistance Simulation for Shells
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RE: [Algorithms] Simple Air Resistance Simulation for Shells
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From: Jamie F. <ja...@qu...> - 2002-09-18 10:43:39
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take your pick, really. just have some acceleration opposing your velocity. you can have a factor of your velocity, or the square of your velocity, or whatever. all are variously inaccurate, but may well give you the effect you're after. then it's simple integration to get your velocity and position. but you may well not find an analytic solution, if that's what you're after, as they don't always exist. jamie -----Original Message----- From: gda...@li... [mailto:gda...@li...]On Behalf Of Hansen, Daniel Sent: 18 September 2002 09:22 To: gda...@li... Subject: RE: [Algorithms] Simple Air Resistance Simulation for Shells Has anyone parametricized the velocity and position taking air-resistance into consideration. I.e v(t) = v0 + a * t p(t) = p0 + (v0 + 0.5 * a * t) * t ..could be used when there's no air-resistance. I'd like something similar with air-resistance. I've seen some formulas with alot of nasty exponents in them, I'm looking for a simpler hack. Anyone? -----Original Message----- From: Charles Bloom [mailto:cb...@cb...] Sent: den 11 september 2002 07:58 To: gda...@li... Subject: RE: [Algorithms] Simple Air Resistance Simulation for Shells This "midpoint method" is 2nd order Runge-Kutta. See, for example : http://www.sst.ph.ic.ac.uk/angus/Lectures/compphys/node11.html http://csep1.phy.ornl.gov/ode/node7.html The traditional so-called "Runge-Kutta method" is the 4th order method. Anyway, all silliness, but some of the stuff on the web is pretty good. At 12:19 AM 9/11/2002 -0400, ja...@jn... wrote: >Thanks to all. Using the midpoint method combined with a small enough time >step appears to provide a reasonable amount of accuracy for my use. I'll >keep Runge-Kutta in mind for future use if it proves necessary. > >Jack > >-----Original Message----- >From: Chris Butcher (BUNGIE) [mailto:cbu...@mi...] >Sent: Monday, September 09, 2002 2:52 PM >To: Jon Watte; ja...@jn...; gda...@li... >Subject: RE: [Algorithms] Simple Air Resistance Simulation for Shells > > >Even using something as simple as the midpoint method (a second-order >integrator) will give much better results for minimal effort. Runge-Kutta >is probably overkill... ? > >v_intermediate= v - 0.5*k(v^2)t; >v_final= v - k(v_intermediate^2)t; > >-- >Chris Butcher >Rendering & Simulation Lead >Halo 2 | Bungie Studios >bu...@bu... > > >-----Original Message----- >From: Jon Watte [mailto:hp...@mi...] >Sent: Monday, September 09, 2002 12:43 >To: ja...@jn...; gda...@li... >Subject: RE: [Algorithms] Simple Air Resistance Simulation for Shells > > >> I'm trying to do a simple ballistics model for shells. The formula I'm >> using is: >> >> v' = v - k(v^2)t; > >This is a first-order Euler integrator (I believe). These are known >to be unstable at any time step -- as you notice :-) > >The typical answer when faced with numerical integration problems >is to turn to a fourth-order Runge-Kutta integrator. I'm sure if you >plug that into Google, you'll get a massive number of hits. It might >show up on MathWorld, too. > >Cheers, > > / h+ > > > > >-------------------------------------------------------------------- >mail2web - Check your email from the web at >http://mail2web.com/ . > > > > >------------------------------------------------------- >In remembrance >www.osdn.com/911/ >_______________________________________________ >GDAlgorithms-list mailing list >GDA...@li... >https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list >Archives: >http://sourceforge.net/mailarchive/forum.php?forum_ida88 > ------------------------------------------------------- Charles Bloom cb...@cb... http://www.cbloom.com ------------------------------------------------------- In remembrance www.osdn.com/911/ _______________________________________________ GDAlgorithms-list mailing list GDA...@li... https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list Archives: http://sourceforge.net/mailarchive/forum.php?forum_id=6188 ------------------------------------------------------- This SF.NET email is sponsored by: AMD - Your access to the experts on Hammer Technology! Open Source & Linux Developers, register now for the AMD Developer Symposium. Code: EX8664 http://www.developwithamd.com/developerlab _______________________________________________ GDAlgorithms-list mailing list GDA...@li... https://lists.sourceforge.net/lists/listinfo/gdalgorithms-list Archives: http://sourceforge.net/mailarchive/forum.php?forum_id=6188 |