OpenSimulator currently only uses bounding boxes for llCastRay(), regardless of the physics engine selected. Other collisions are computed in the physics engine, and in the case of BulletSIm or ODE, are computed against mesh triangles or convex hulls, and are usually quite accurate.
On Tue, Feb 25, 2014 at 7:46 PM, Dr Ramesh Ramloll <r.raml...@gmail.com>wrote: > Hello, are we to assume that opensim will only use bounding boxes for > llCastRay or when detecting collisions? There are a lot of compelling > applications that require the data for the point at which the ray hits the > surface of a mesh object or for the point of collision on a mesh object. Is > this one area where Second Life is definitely ahead because of Havok4? I am > not very familiar with the underlying opensim infrastructure, so would be > glad to hear more about this. > Thanks > R > > > On Tue, Feb 25, 2014 at 12:00 PM, Chris <mewtwo0...@gmail.com> wrote: > >> If I recall correctly, the default physics engine was switched to >> BulletSim some time ago although I can't recall when. Assuming recent code >> is being used and also assuming the physics engine hadn't been switched >> from default I would venture to say that BulletSim is likely being used, >> but, that is just a guess on my part based on what I've seen and >> experimented with myself; I have no idea what setup OSGrid is using since >> it has been a while since I've ran a sim connected there. >> >> I haven't had a chance to test this myself on BulletSim but I have >> noticed some slight quirkiness with cast ray on some surfaces (especially >> angled prims). I've not given it a full run on tests as I haven't used the >> cast ray functions all that much in my scripting. >> >> >> On 2/25/2014 10:48 AM, Handy Low wrote: >> >>> Gwyneth Llewelyn <gwyneth.llewelyn <at> gwynethllewelyn.net> writes: >>> >>> Hi Handy, >>>> >>>> Just for the sake of completeness, did you test with ODE or BulletSim? I >>>> >>> believe the implementation might be >>> >>>> slightly different (or, then again, it's just my not-so-precise >>>> testing). >>>> >>>> Thanks, >>>> >>>> - Gwyn >>>> >>>> On 25/02/2014, at 16:09, Handy Low wrote: >>>> >>>> Currently it seems that the OpenSim implementation of llCastRay() gives >>>>> coordinates on a target object that lie on the bounding box of the >>>>> >>>> object >>> >>>> rather than on the face of the prim itself. >>>>> >>>>> For example, casting a ray at a pair of linked cubes in OpenSim will >>>>> >>>> generate >>> >>>> coordinates that lie on the cuboid bounding box that constrains both >>>>> >>>> cubes. >>> >>>> Likewise, casting a ray at a sphere will generate a point on the >>>>> >>>> sphere's >>> >>>> cubic bounding box. >>>>> >>>>> In SL, the same tests will both return points on the prim surfaces. >>>>> >>>>> Is this expected behaviour? >>>>> >>>>> Thanks >>>>> >>>> Thanks to Michael and Gwen for the fast replies. >>> >>> Off the top of my head, I don't know which physics engine they were >>> using, >>> or how I can find out - the tests I've been doing have been in OSGrid >>> (Sandbox Plaza) and in Kitely, if that's any help. >>> >>> -- >>> Handy >>> >>> _______________________________________________ >>> Opensim-users mailing list >>> Opensim-users@lists.berlios.de >>> https://lists.berlios.de/mailman/listinfo/opensim-users >>> >> >> >> -- >> OpenSim: 10 Region Standalone on 0.7.6 Dev >> Physics: Open Dynamics Engine >> OS: Windows 7 (x64) >> CPU: AMD Phenom II X4 840 3.2 GHz >> Memory: 11 GB DDR3 >> Database: MySQL 5.1.63 (x64) >> >> >> _______________________________________________ >> Opensim-users mailing list >> Opensim-users@lists.berlios.de >> https://lists.berlios.de/mailman/listinfo/opensim-users >> > > > > -- > 'Consider how the lilies grow. They do not labor or spin.' > *Rameshsharma Ramloll* PhD, CEO CTO DeepSemaphore LLC, Affiliate *Research > Associate Professor*, Idaho State University, Pocatello, ID 83209 Tel: > 208-240-0040 > LinkedIn <http://www.linkedin.com/in/rameshramloll>, DeepSemaphore > LLC<http://www.deepsemaphore.com>, > RezMela <http://www.rezmela.com>, Google+ > profile<https://plus.google.com/103652369558830540272/about> > > _______________________________________________ > Opensim-users mailing list > Opensim-users@lists.berlios.de > https://lists.berlios.de/mailman/listinfo/opensim-users >
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