Deforming Rigidbody By Chops

[Rafal123]

let's say I gotta sphere connected to transform, then scaleY of the transform is connected to CHOP wave so it's scaled by wave up and down,

now I use this sphere in DOPs as a RBD, what I want is spheres scaleY be updated in DOPs, there's no problem with animated sphere-->transform-->scaleY channel, but with CHOPs I don't know how do it... can anybody help?

[peship]

You are using CHOPs to animate object's transformation channels ? Then inside the RBD Object check "use object's transform".

You will meet the old problem with animated transformations and DOP's, i would love to hear any solution about that. Anyone ?

[craig]

You are using CHOPs to animate object's transformation channels ? Then inside the RBD Object check "use object's transform".

You will meet the old problem with animated transformations and DOP's, i would love to hear any solution about that. Anyone ?

27570[/snapback]

What is this old problem? If you want to use an animated transform that doesn't deform the object's shape, then you should use one of the nodes in the Position submenu of the tab menu, namely

Motion

Object Position

Position

RBD State

RBD Keyframe

Point Position

If the object is deforming (as it is in Rafal123's example) then you need to turn on

"Use Object Transform" AND set "Use Animated Geometry" to 1.

[Rafal123]

it was somethin with my H (I think), coz now it works, strange...

sorry

[peship]

Oh, sorry, i should mention what i mean.

So, the problem i am talking about can be easily seen if you create a objectOP and put inside it a sphereSOP, turn the sphere to polygons.

Animate the scaleY of the objectOP ( a sin function with low frequency is going to be good for that ).

Create a DOP network with RBD object, ground plane and gravity.

Use the sphere as RBD and play the simulation.

When the sphere stop bouncing on the ground plane you will see that when scaleY is decreasing the dynamic simulation looks right, but when the scaleY is increasing, then the sphere is penetrating with the ground plane ( or other RBD objects ) instead of colliding properly.

Do you know how to avoid this ?

Thanks.

[Rafal123]

man, check on 'use point velocity on collisions'' --> on rbd_solver

p.s

hey people can U also check setup like here? :

http://www.rafal.stnet.pl/dyn_test.jpg

is that normal that sphere behave like it behave? I mean it go through to box surface, I thought it somethin with normals on box but not, I reversed normals and it still behave the same way

[peship]

Great.

This thing bugged me out for long time.

[craig]

man, check on 'use point velocity on collisions''  --> on rbd_solver

p.s

hey people can U also check setup like here? :

http://www.rafal.stnet.pl/dyn_test.jpg

is that normal that sphere behave like it behave? I mean it go through to box surface, I thought it somethin with normals on box but not, I reversed normals and it still behave the same way

27623[/snapback]

If you set the Contact Grouping Method to "Average Point" in the RBD Solver, then you get the same motion for Volume Based Collisions as for Surfaces. And if you set the ball object's collision volume Mode to Implicit Sphere, you also get a straight bounceback. So my theory is that with the surface collision, you only get a single collision, so the ball bounces back up in the direction it came from. With the volume based collision, you actually get several tiny impacts, and so it bounces off at an angle.

[Rafal123]

yo craig, thanks for info man