These algorithms have been very helpful; thanks everyone :) -Dusten
2008/11/27 Middleton, Colin (GE EntSol, Intelligent Platforms) < [EMAIL PROTECTED]> > > > Another simple way of calculating the volume of a arbitary closed 3d mesh > is > > Choose an arbitary point ( let's call it o ) > For each triangle with vertices ( a,b,c ) > Calculate the volume of the tetrahedron ( a,b,c,o ) using a scalar triple > product ( ((b-a)x(c-a)).(o-a)/3 ). > Add the volumes of all of the tetrahedrons together, some of these volume > will be negative and some will be positive, depending on whether the > triangle is facing the arbitary point or not. These negative volumes cancel > out the positive ones, leaving only the enclosed area. > > This relies on the 2 assumptions:- > 1) All of the triangles in the 3d object have the same winding order, > otherwise the volumes' sign cannot be trusted. > 2) The object has no holes. > > If the object has holes then the placing of the arbitary point will affect > the volume of the object, a triangular hole will mean that the volume of a > tetrahedron between the hole and the arbitary point will be missed in the > calcalation. As a result of this placing it in the centroid of the 3d object > is probably the best plan. > > I hope this helps. > > Colin. > > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] On Behalf > > Of Alberto Luaces > > Sent: 27 November 2008 08:42 > > To: OpenSceneGraph Users > > Subject: Re: [osg-users] Calculating the volume of a model through OSG > > > > Hi, > > > > in addition to Janusz pointers, if you need also the rest of > > the mass properties, you could take a look at this famous paper: > > > > http://www.cs.berkeley.edu/~jfc/mirtich/massProps.html > > > > Alberto > > > > El Jueves 27 Noviembre 2008ES 09:09:34 [EMAIL PROTECTED] escribió: > > > Dusten: > > > > > > You might find these two helpful: > > > > > > accurate: http://tetgen.berlios.de/ > > > approximate & simple: > > > http://www.gamedev.net/reference/articles/article2247.asp > > > > > > The second one could be easily added to osg I guess. > > > Janusz > > > > > > Dnia Wed, 26 Nov 2008 23:47:57 -0600, Dusten Sobotta napisał(a): > > > > Hello, > > > > > > > > Manually modifying various attributes of models is quite tedious, > > > > and tends to set back the development of games. To work > > around this > > > > issue, I'd like to implement a feature to calculate the > > volume of an > > > > in-game model, so that given a surface attribute such as > > 'wood' or > > > > 'metal', (which have pre-defined density values), the mass of an > > > > object can be computed and later exported. Might anyone have an > > > > example for finding the approximate volume of an object > > through OSG? > > > > > > > > > > > > Thanks in advance, > > > > > > > > Dusten > > > > _______________________________________________ > > > > osg-users mailing list > > > > [email protected] > > > > > > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegrap > > > > h.org > > > > > > _______________________________________________ > > > osg-users mailing list > > > [email protected] > > > > > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph. > > > org > > > > > > _______________________________________________ > > osg-users mailing list > > [email protected] > > http://lists.openscenegraph.org/listinfo.cgi/osg-users-opensce > > negraph.org > > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >
_______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
