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Re: Repulsion between physical and other objects
by Jippen Faddoul
::
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I've had to deal with making a ferris wheel in SL. Since they move
quite slowly, I just use llSetRot and llSetPos to make it rotate one
degree a second. Swiped most of the code for it from a circle building
tool. You can prolly find it at Yadni's. Gave me a 6 minute revolution
time, which is pretty nice for a ferris wheel, and was smooth enough.
Making the carriages swing would add some additional math to it, but
shouldn't be too complicated.
On Wed, Sep 3, 2008 at 5:52 AM, Ron Blechner <ron@...> wrote:
> "Havok (our physics engine) uses a Collision Tolerance of 0.1m. What
> this means basically is that there is a 0.1m buffer between objects.
> This makes the physics calculations simpler and helps prevent
> interpenetrations."
>
> Hm, maybe I missed the memo... wasn't Havok4 supposed to reduce this?
>
> On Wed, Sep 3, 2008 at 8:24 AM, G <gcanaday@...> wrote:
>> The physics engine doesn't work well with machinery. Generally speaking, I'd
>> write in a sensor that locates a central object and uses llSetPos() and
>> llSetRot() to match. I did this with a rotating clock pendulum and a swing.
>> You can still rotate the central object and the wheel will follow within the
>> sensor repeat time. If the object hasn't moved (or has only moved < .1M,
>> say), you can easily just rotate it around where the "shaft" would be and
>> people can hop on and ride at will. This also frees you from the 31-prim
>> (including sitters!) physical prim limit since you don't need physics, so
>> you can make a huge one if you like. The only hard part is remembering how
>> to multiply / divide the quaternion rotations ;)
>>
>> G
>>
>> Anderson Philbin wrote:
>>>
>>> Hi,
>>> I'm trying to build a rotating mechanism similar to a ferris wheel.
>>> llTargetOmega should do the trick but my problem is controlling the
>>> repulsion between the objects. For example, a hollow cylinder around a shaft
>>> will tear itself off the shaft if you change it to physical. The repulsion
>>> effect seems to die down at about 100-125 mm clearance.
>>> I've left a hollow cylinder happily spinning about a shaft with end caps,
>>> all with 125 mm clearance. I come back an hour later and the cylinder is
>>> laying on the ground. I understand the repulsion is provided by Havok 4 when
>>> objects interpenetrate but I'm trying to find out how to measure it and,
>>> perhaps, control it. Also, there seems to be a friction effect too. My
>>> full-size object just binds, it doesn't rotate at all.
>>> Is there any documentation on this? Should I be trying to independently
>>> move the components rather than using spacial contraints?
>>> TIA
>>> Anderson Philbin
>>> ------------------------------------------------------------------------
>>>
>>> _______________________________________________
>>> Click here to unsubscribe or manage your list subscription:
>>> https://lists.secondlife.com/cgi-bin/mailman/listinfo/secondlifescripters
>>>
>>
>> _______________________________________________
>> Click here to unsubscribe or manage your list subscription:
>> https://lists.secondlife.com/cgi-bin/mailman/listinfo/secondlifescripters
>>
>
>
>
> --
> Ron Blechner
> Chief Technology Officer
> Involve, Inc
> www.involve3d.com
> SL: Hiro Pendragon
> _______________________________________________
> Click here to unsubscribe or manage your list subscription:
> https://lists.secondlife.com/cgi-bin/mailman/listinfo/secondlifescripters
>_______________________________________________
Click here to unsubscribe or manage your list subscription:
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quite slowly, I just use llSetRot and llSetPos to make it rotate one
degree a second. Swiped most of the code for it from a circle building
tool. You can prolly find it at Yadni's. Gave me a 6 minute revolution
time, which is pretty nice for a ferris wheel, and was smooth enough.
Making the carriages swing would add some additional math to it, but
shouldn't be too complicated.
On Wed, Sep 3, 2008 at 5:52 AM, Ron Blechner <ron@...> wrote:
> "Havok (our physics engine) uses a Collision Tolerance of 0.1m. What
> this means basically is that there is a 0.1m buffer between objects.
> This makes the physics calculations simpler and helps prevent
> interpenetrations."
>
> Hm, maybe I missed the memo... wasn't Havok4 supposed to reduce this?
>
> On Wed, Sep 3, 2008 at 8:24 AM, G <gcanaday@...> wrote:
>> The physics engine doesn't work well with machinery. Generally speaking, I'd
>> write in a sensor that locates a central object and uses llSetPos() and
>> llSetRot() to match. I did this with a rotating clock pendulum and a swing.
>> You can still rotate the central object and the wheel will follow within the
>> sensor repeat time. If the object hasn't moved (or has only moved < .1M,
>> say), you can easily just rotate it around where the "shaft" would be and
>> people can hop on and ride at will. This also frees you from the 31-prim
>> (including sitters!) physical prim limit since you don't need physics, so
>> you can make a huge one if you like. The only hard part is remembering how
>> to multiply / divide the quaternion rotations ;)
>>
>> G
>>
>> Anderson Philbin wrote:
>>>
>>> Hi,
>>> I'm trying to build a rotating mechanism similar to a ferris wheel.
>>> llTargetOmega should do the trick but my problem is controlling the
>>> repulsion between the objects. For example, a hollow cylinder around a shaft
>>> will tear itself off the shaft if you change it to physical. The repulsion
>>> effect seems to die down at about 100-125 mm clearance.
>>> I've left a hollow cylinder happily spinning about a shaft with end caps,
>>> all with 125 mm clearance. I come back an hour later and the cylinder is
>>> laying on the ground. I understand the repulsion is provided by Havok 4 when
>>> objects interpenetrate but I'm trying to find out how to measure it and,
>>> perhaps, control it. Also, there seems to be a friction effect too. My
>>> full-size object just binds, it doesn't rotate at all.
>>> Is there any documentation on this? Should I be trying to independently
>>> move the components rather than using spacial contraints?
>>> TIA
>>> Anderson Philbin
>>> ------------------------------------------------------------------------
>>>
>>> _______________________________________________
>>> Click here to unsubscribe or manage your list subscription:
>>> https://lists.secondlife.com/cgi-bin/mailman/listinfo/secondlifescripters
>>>
>>
>> _______________________________________________
>> Click here to unsubscribe or manage your list subscription:
>> https://lists.secondlife.com/cgi-bin/mailman/listinfo/secondlifescripters
>>
>
>
>
> --
> Ron Blechner
> Chief Technology Officer
> Involve, Inc
> www.involve3d.com
> SL: Hiro Pendragon
> _______________________________________________
> Click here to unsubscribe or manage your list subscription:
> https://lists.secondlife.com/cgi-bin/mailman/listinfo/secondlifescripters
>
Click here to unsubscribe or manage your list subscription:
https://lists.secondlife.com/cgi-bin/mailman/listinfo/secondlifescripters
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