Re: Repulsion between physical and other objects

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

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.  But it also means physical things won't really touch.  You can see this effect clearly if you rez 1 physical cube, then rez another above it and let it drop onto the first.  After they settle you can clearly see the gap between them.

 - Kelly

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