[Opensim-users] llCastRay and object shapes

[Dr Ramesh Ramloll]

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 <mewtwo0641 at 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
>>
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>
>
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