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VermilionCat
02-10-2013, 01:56 AM
Hi,

It seems collision mesh as Deforming Body in Bullet doesn't retain its shape.
For instance, open Sleeve_Deforming_Body_Collider.lws from contents and see the result by ticking Bullet on and off.
In my opinion, collision mesh should completely retain the shape. Is there any ways to achieve this?

VermilionCat
02-10-2013, 11:52 PM
Any comment would be nice. I think this is serious in the world 10mm matters.

UnCommonGrafx
02-11-2013, 03:21 AM
Mesh filter and shape retention are your friend in this case.

As everything can be a collision, only in differing body shapes, Bullet presumably only knows what you tell it to; you have to tell it that the deforming body that is the collision needs to keep it's shape, 100%, not flatten nor bend with 100% stiffness and so on.

They do work great as collision pieces in the scene.

Thomas Leitner
02-11-2013, 04:28 AM
Mesh filter and shape retention are your friend in this case.

As everything can be a collision, only in differing body shapes, Bullet presumably only knows what you tell it to; you have to tell it that the deforming body that is the collision needs to keep it's shape, 100%, not flatten nor bend with 100% stiffness and so on.

They do work great as collision pieces in the scene.

Hi,
No, Mesh Filter doesn´t work because you only can separate a mesh from bullet complete (no collision too).
And Shape Retention at 100% doesn´t stop bullet simulation complete (there is still a deformation) and I think this is what VermilionCat means.

ciao
Thomas

UnCommonGrafx
02-11-2013, 04:54 AM
I think an example is warranted from the OP.

In my initial test, I had a chair, set as deforming object, act as the collision object. It did not deform when a cloth object was thrown over it.
In hindsight, I don't recall having to change anything to make it stay static.

For mesh filter, think in reverse: make the underside, one polygon even, the 100% piece while the rest of the object stays at 0. Only that one piece will react in deforming, while the rest stays static.

Or so I hypothesize.

UnCommonGrafx
02-11-2013, 05:04 AM
I think an example is warranted from the OP.

In my initial test, I had a chair act as the collision object. It did not deform when a cloth object was thrown over it.
In hindsight, I don't recall having to change anything to make it stay static.

For mesh filter, think in reverse: make the underside, one polygon eve, the 100% piece while the rest of the object stays at 0. Only that one piece will react in deforming, while the rest stays static.
__I read you saying this won't work. I have to give it a go later.

Or so I hypothesize.

- - - Updated - - -

Ah... hmmm...
a certain amount of edits makes for a new post?

- - - Updated - - -

very interesting...

- - - Updated - - -

Learning the new forum...

So all subsequent "conversations to self" are updates?

VermilionCat
02-11-2013, 10:51 PM
Thanks for the comment.

Is this the current limitation for Bullet?
I expected something similar to ClothFX for collision mesh...
It seems there's no solution yet...

Here's the example.

LightFreeze
02-12-2013, 12:15 AM
the character is a deforming mesh, the hair is a deforming mesh, they both have bullet and both have mdd nodal deformations, the character has 100% Shape Retention.


http://www.youtube.com/watch?v=n8wLsN7PdYI

VermilionCat
02-12-2013, 01:04 AM
the character is a deforming mesh, the hair is a deforming mesh, they both have bullet and both have mdd nodal deformations, the character has 100% Shape Retention.

You're right! LightFreeze!
Baking MDD for the collision mesh before the simulation is a must in this case.

Thanks!!