[ODE] Kinematic objects

[J. Perkins]

On 10/28/05, Jaroslav Sinecky <jsinecky at tiscali.cz> wrote:
> Good point, the friction. If you just move static geoms around in each step,
> you don't get correct friction on them. Fortunately what you call "moving
> ground point" - don't we have the dContactMotion flag in ODE? (feature that
> I have seen no use so far) Seems like perfect solution waiting for this
> problem.

My original suggestion was to use a body for kinematic objects, but it
a different ODE world, and apply impulses to the body to move it
around. So the trick is how to pass this information into ODE to
resolve the collision, but no allow ODE to apply forces to the
kinematic body.

There was a discussion quite a ways back about having a special case
in the collider for objects with widely disparate masses, like a tank
hitting a beach ball. The idea was to treat the heavier object as if
it had infinite mass. That solution would also help with kinematic
objects. I don't think anything came of it, but it might be something
I can look into.


> Jason, what happens if kinematic object hits the wall ... sounds to me like
> the problem of "What happens if all-penetrating ball hits unpenetratable
> armour ..."

I don't agree with this. I have a player character, and I want it to
push dynamic objects out the way. I don't want it to walk through
walls. Which is why I want to have a dBody behind the kinematic
object, so that it can still collide with static geometry.

I hadn't thought of a kinematic player on a moving platform, where the
platform should be able to push the player around. Have to think about
that.

Jason