reference application

muppet · Post by **muppet** » Mon Jan 17, 2005 10:51 pm

Hi,

I noticed that if you hit a box against the stairs/steps in the bsp collision demo, the box random acts like it has been given an extra push of force and flies off with a very fast speed. This obviously doesnt simulate what would really happen.

Does anyone know the reason for this? If so how is it solvable? I have studied the code for it, but cannot figure out why this occurs.

Thanks in advance.

Post by **sinbad** » Tue Jan 18, 2005 2:34 pm

It's because Q3A only provides planes for collision, and is really only designed for single-point collision. To do it properly we'd have to construct more complex collision proxies from the intersection of planes, which we haven't done in this case - it's just an example which is convincing enough in most cases.

muppet · Post by **muppet** » Tue Jan 18, 2005 10:44 pm

Ok cool thx for that its cleared some stuff up for me...although I'm still not sure why this thing occurs with the boxes. I mean what actually causes them to speed up like they do? and obviously what difference does more complex geometry make?

Thanks

muppet · Post by **muppet** » Wed Jan 19, 2005 11:47 pm

Sorry to be a pain but...has anyone got any suggestions?

Post by **sinbad** » Thu Jan 20, 2005 12:07 am

It's the inaccuracy - the collision is probably detected at a penetration depth deeper than would notmally happen if you had more accurate collision so it thinks the response force should be higher than it actually is.

You might be able to improve this by increasing the number of contact points on the boxes, see the ODE docs for details.