From: metanet software <metanet_gda4@ya...>  20100206 15:20:28

> Since the capsules are mathematically defined by a length > and a radius there are no surfaces so I suggest using > standard collision detection instead. There are standard > intersection tests that return a collision normal along with > a intersection distance. I'm guessing you can find it in > most open source physics libraries or just google it. This is tricky, because the actual collision surface (i.e the outer surface of the union of capsules) is implicit; you can't simply apply a capsulebased method and expect a correct result. For example: L1 S1     _ac___S2  *b _____L2 L1 and L2 are capsule linesegments; the capsule surfaces (S1,S2) intersect at c. If you query at the asterisk, you should get c as closest point on the surface. There's no way to arrive at this through simple pointvscapsule queries  pointvsL1 will give you b, pointvsL2 will give you a. You _can_ try to iteratively push the point out of each capsule and hope that it eventually reaches the surface; in the above case this would work, but in general it doesn't. AFAIK there is no correct way to take the many local solutions you would get from individual pointvscapsule queries and "munge" them together to arrive at a correct global solution. If there *is* such a method, I'd love to know about it though since it would be extremely useful. Currently we just use "iteratively project out of local collisions, and pray" :) raigan  On Thu, 2/4/10, pontus birgersson <herruppohoppa@...> wrote: > From: pontus birgersson <herruppohoppa@...> > Subject: Re: [Algorithms] Algorithm to return point to surface of concave volume > To: "GDAlgorithms" <gdalgorithmslist@...> > Received: Thursday, February 4, 2010, 10:36 AM > > > > > > Andreas, > > Since the capsules are mathematically defined by a length > and a radius there are no surfaces so I suggest using > standard collision detection instead. There are standard > intersection tests that return a collision normal along with > a intersection distance. I'm guessing you can find it in > most open source physics libraries or just google it. > > If you need increased performance you can always attempt to > use proxy objects or perhaps switch primitive from capsule > to something easier. > > Hope that helps, > Pontus > > > Date: Wed, 3 Feb 2010 11:54:45 +0100 > From: andreas.brinck@... > To: gdalgorithmslist@... > Subject: [Algorithms] Algorithm to return point to surface > of concave volume > > Hi, > > I have a point inside a concave volume, does anyone know of > an algorithm to find the shortest vector from the point to > the surface of the volume? The volume in this case is > defined as the union of a number of overlapping capsules > (lines with radius). > > > Thanks > > Andreas Brinck > > Skaffa en Windows phone så kan du > chatta på Messenger var du än är! Skaffa en > Windows phone så kan du chatta på Messenger var du än > är! > > Inline Attachment Follows > >  > The Planet: dedicated and managed hosting, cloud storage, > colocation > Stay online with enterprise data centers and the best > network in the business > Choose flexible plans and management services without > longterm contracts > Personal 24x7 support from experience hosting pros just a > phone call away. > http://p.sf.net/sfu/theplanetcom > Inline Attachment Follows > > _______________________________________________ > GDAlgorithmslist mailing list > GDAlgorithmslist@... > https://lists.sourceforge.net/lists/listinfo/gdalgorithmslist > Archives: > http://sourceforge.net/mailarchive/forum.php?forum_name=gdalgorithmslist __________________________________________________________________ Ask a question on any topic and get answers from real people. Go to Yahoo! Answers and share what you know at http://ca.answers.yahoo.com 