[ODE] Adding Negative Masses

[Bram Stolk]

Wesley Smith wrote:
> Hi,
> I'm curious is if it's possible to use dMassAdd() to add a negative
> mass to a large mass and have the result be as if a chunk of that mass
> went missing of the corresponding form.  For  example, if I do
> dMassAdd(), combining 3 objects, and now want to take one of them
> away.  Assuming that I've kept some record of the original small
> body's mass, can I negate it's mass params in the dMass struct and
> then call dMassAdd(&compositeMass, &body2) and have it behave as if
> body 2 had been taken away?  I'm guessing yes, but I want to be sure.
> 

Hey... nice idea.
I can't say for sure, but my guess is that it works.
You'll just have to try.

It would be nice to have an example that simulates a 
helium balloon in ODE. Or a hindenburg? Cool! I just may try that
in my spare time :-)

 Bram