[ODE] Electro static forces

NoWay InHell zinkala at gmail.com
Mon Jun 13 10:05:33 MST 2005

Your solution to this problem depends on the reason why you need a
magnet and how you're planning on using it.  If you're just looking to
create a point source then the suggested solutions will work fine.
The easiest method would be to create a custom geom, define an AABB
for the max range of your magnet force, and then apply your forces
during the collision calls (IMHO).  This would at least immediately
filter out all those objects outside of your magnets range.

However, this will not simulate a magnet to any degree of accuracy.
You've got three main issues -

(1) A magnet's force should be generated across the entire surface
area of the source object.  This is an important distinction.

(2) Creating a force field in ODE is problematic as it tends to induce
rotations.  We all know what happens to objects rotating in ODE

(3) Because of the penalty method itself, your fero-magnetic objects
will NOT tend to there state of greatest entropy. They will come to
rest at unnatural positions/rotations in relation to the magnet

Solving the above three problems is left as an exercise to the reader -)

 - Zink

On 6/11/05, Mohamed Matar <Mohamed.Matar at gmx.de> wrote:
> TO all brilliant minds and ODE geeks :) :)
> I have two objects that acts like a magnet. Anyone have any idea how to
> model this. Forces start to kick off before the objects touch.
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