IRC log for #brlcad on 20120926

00:34.29 brlcad starseeker: uhm, because "The code embodies decades of research and experience by Pixar, and a more recent and still active collaboration on fast GPU drawing between Microsoft Research and Pixar." :)
00:36.46 brlcad interesting font, looks like adobe themselves published it: http://www.tested.com/news/443102-adobe-releases-monospaced-open-source-font-source-code-pro/
00:38.09 brlcad elf11_: I guess I'm still not seeing the problem -- if you know the values being fed to bullet are always a specific unit, you are providing bullet with a model sized consistently
00:39.01 brlcad elf11_: is the problem that small objects will traverse a large distance with very few simulation steps or something like that?
00:48.28 elf11_ brlcad, the thing is that you are feeding bullet what's stored in brl-cad, so if for example the simulation I did in mm will be translated to m, then since brl-cad stores sizes in mm, bullet will get 50000 m and not 50 000 mm from brl-cad, hence the scaling
00:49.36 elf11_ and small geometry results are not reliable because, bullet has a tolerance of 0.04m that's like 40mm, the simulation I did the biggest geometry was 30mm, lower than the tolerance
00:49.42 elf11_ so the cube was penetrating the surface
00:50.33 brlcad elf11_: okay, but the mm to m translation would just be a one-time bug to get fixed
00:51.14 brlcad that also seems like a very high tolerance -- is it configurable?
00:52.15 brlcad moreover, what would be the impact of scaling the geometry up so that it's always an order bigger than that tolerance?
00:52.52 elf11_ the mm to m translation is a few lines of code fix
00:53.23 elf11_ about the configurable part looked into it, didn't find yet a way to get it lower
00:53.27 brlcad or always scaling 10^6 even unless values are >10^6 already
00:55.56 elf11_ hmm I tried the simulation I did for values like 10^2 bigger than the ones used, and it worked - the cube didn't fall through the plane, like just meter scaling all the geometry under the tolerance
01:08.46 brlcad elf11_: the issue might be the rate at which it simulates
01:09.29 brlcad you want X time steps to equate to the same amount of time and for the mass being simulated to reflect the sizes in brl-cad, not whatever size it might have been scaled to
01:10.12 brlcad you could compensate with a 10^6 scaling with a similar mass scaling, but it'd have to be done carefully to be correct
01:11.11 brlcad best to start as simple possible, unscaled and just document that you the model should be larger than 40mm in order for collision detection to be evaluated correctly
01:11.58 elf11_ okay
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03:04.59 yukonbob hello #brlcad
03:17.47 brlcad howdy
03:18.46 yukonbob :)
03:19.13 yukonbob just saw news of Sony OSL, looked at license. Very impressed.
03:42.57 yukonbob brlcad: how're things going?
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13:34.37 brlcad starseeker: interesting, rhino mostly punted: http://wiki.mcneel.com/rhino/meshtonurb
13:35.02 brlcad though that base case does have some interesting implications that could be useful to support
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20:53.42 starseeker Hmm - CIA still not working
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