View Full Version : Colision detection?

06 June 2002, 05:15 PM
How do you get a null to detect collisions? Can you do it on the object level or is it limited to the soft-body (and particle/fluid) operators? Soft body creates too many problems to work around.
Thanks in advance.

06 June 2002, 06:23 AM
nah lakehaze there's no way to do that...I'm 99.99% sure

What are you trying to do that softbodies are giving u such problems with. Cause if ya specifically say what ya trying to do we might have some solutions\workarounds for ya :)

07 July 2002, 05:06 PM
Im trying to setup a vehicle suspension rig. The wheels would ride on an 'axel' which was a child of a floor hieght null that would collide with the (uneven) ground plane and be pulled by a constraint to a 'shock' that would attach it to the body. Anyway that was the plan. I tried to use a single poly grid instead of a null and apply a soft body, but only the grids geometry was effected, not the center (which would punch right through the floor, and bring the wheel with it). And it would stop listening to its parent, the 'shock', and just sit in one spot in x and z.


07 July 2002, 06:42 PM
How about if you went back to the grid method and set up a cluster on it. Then, with compensation, constrain the wheel to the cluster centre.
Might take a little playing with/tweaking, but I think it should work.

07 July 2002, 06:47 PM
maybe i got you completely wrong, but is an object to cluster constraint what youīr looking for? for example: get a simple 4 point grid --> shrinkwrap it to your uneven ground--->select itīs points --> make a cluster--> constraint a null to that cluster.

as i said, i might got you wrong due to my horrible english skills.

cheers, felix

07 July 2002, 06:51 PM
Felixx, I think we more or less suggested similar solutions:beer:
Run with it lakehaze, see what happens.

07 July 2002, 07:26 PM
hehe, cheers Bradf0rd010 :beer:

didnīt see your post when replying.

lakehaze: iīm interested in how you plan to make the shockabsorbers. do you write a scripted op from scratch?


07 July 2002, 04:50 PM
Thanks for the replies,

The problm with constraining the wheel to a cluster center is that constraints are center-to-center. The wheel would just stick to the center of the cluster, it wouldn't go up or down are be able to 'roll' anywhere.

What is 'shrinkwrap', and what effect would it have with only 4 points?

" you plan to make the shockabsorbers. do you write a scripted op from scratch?"-Nono, Im no programmer, i would just set up a constraint on the 'Axel' that would be offset however many units below a 'strut-mount' (Implicit cube...). It would do all it could to stay down there, but when the floor-hight hit the ground it would push the axel back toward the strut, similar to a leg rig.

The problem with the leg rig is that you have to animate the floor-hight. Not to big a problem when the foot doesn't move on the ground, you can move it when the foot is in the air. But on a wheel, it rests on the ground always, if i were going to animate the floor-hight to match the terrain i may as well just animate the wheel itself, in which case there is no rig at all.

I need a floor-hight device that collides with the ground, a dynamic. The only thing i can think of is really compcated script. I think ill post that as a new post so that it isn't buried in this reply.

Again thanks for the ideas,:wip:

07 July 2002, 08:27 AM
might be totally wrong here but have you messed around with constrain -> bounding plane and selecting your ground grid as the object?? Should solve the problem of the wheels crashing through the ground..
As for the shock absorbers i'd put in some bones and constrain the apposing effectors positionally to the roots and parenting the appropriate pieces of the shocks/wheels to the bones.

Hope this helps!

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