Rigid-Bodies Colliding Improperly #70505

New Issue

Andy Sellers · 2019-10-04T05:54:11+02:00

Andy Sellers commented

2019-10-04 05:54:11 +02:00

Basic Setup with bug 2.blend
System Information
Operating system: Windows-10-10.0.17134 64 Bits
Graphics card: GeForce GTX 950M/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 436.48

Blender Version
Broken: version: 2.81 (sub 13), branch: master, commit date: 2019-10-03 21:03, hash: fbc096cf07

Short description of error
Some of the Rigid-Body objects in the included .blend go flying when animation is played, as though they were intersecting each other, but they are not.

Exact steps for others to reproduce the error
Open the included .blend.
Play animation. The two objects named "Suspension.FL will go flying off in opposite directions.

[Basic Setup with bug 2.blend](https://archive.blender.org/developer/F7788695/Basic_Setup_with_bug_2.blend) **System Information** Operating system: Windows-10-10.0.17134 64 Bits Graphics card: GeForce GTX 950M/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 436.48 **Blender Version** Broken: version: 2.81 (sub 13), branch: master, commit date: 2019-10-03 21:03, hash: `fbc096cf07` **Short description of error** Some of the Rigid-Body objects in the included .blend go flying when animation is played, as though they were intersecting each other, but they are not. **Exact steps for others to reproduce the error** Open the included .blend. Play animation. The two objects named "Suspension.FL will go flying off in opposite directions.

Andy Sellers commented

2019-10-04 05:54:11 +02:00

Added subscriber: @Andrewm90

Germano Cavalcante commented

2019-10-04 17:54:29 +02:00

Added subscribers: @mont29, @mano-wii

Germano Cavalcante commented

2019-10-04 17:54:29 +02:00

Investigating this problem I came across an assert on this line:
https://developer.blender.org/diffusion/B/browse/master/source/blender/blenkernel/intern/rigidbody.c$1753

For that I deleted one of the rigid body constraints and ran the animation.

It's probably not related to the bug but,
@mont29, could you take a look at this assert first? (the assert was added in 7f98ba47)

Investigating this problem I came across an assert on this line: https://developer.blender.org/diffusion/B/browse/master/source/blender/blenkernel/intern/rigidbody.c$1753 For that I deleted one of the rigid body constraints and ran the animation. It's probably not related to the bug but, @mont29, could you take a look at this assert first? (the assert was added in 7f98ba47)

Bastien Montagne commented

2019-10-04 18:58:23 +02:00

Fixed as bebdb6c824, but this had really nothing to do with this report, besides being a RBW issue…

Fixed as bebdb6c824, but this had really *nothing* to do with this report, besides being a RBW issue…

Sergej Reich was assigned by Germano Cavalcante

2019-10-04 19:51:37 +02:00

Germano Cavalcante commented

2019-10-04 19:51:37 +02:00

Added subscriber: @sreich

Germano Cavalcante commented

2019-10-04 19:51:37 +02:00

On further investigation, this problem has to do with how the Collision margin is calculated for cylinder shape objects.
The problem can be alleviated by reducing the collision margin of all objects involved.

Since you can work around the settings and the bullet collision code is part of an external library, I don't think it's worth investigating this.
But I will leave the decision to close the report to @sreich who knows this area better.

On further investigation, this problem has to do with how the Collision margin is calculated for cylinder shape objects. The problem can be alleviated by reducing the collision margin of all objects involved. Since you can work around the settings and the bullet collision code is part of an external library, I don't think it's worth investigating this. But I will leave the decision to close the report to @sreich who knows this area better.

Andy Sellers commented

2019-10-04 20:02:01 +02:00

As far as I know, the cylinder Collision margin box is not ticked by default, resulting in Blender assuming the value to be 0 automatically. If the box is ticked, then the value is explicitly controlled by the user. Is this the case?

Andy Sellers commented

2019-10-04 20:38:26 +02:00

On a related note, is there a specific reason 2.8x doesn't display the Rigid-Body bounding box shapes in the viewport? 2.7x did this, and it was very helpful. I'm assuming it's intentional and not a bug.

On a related note, is there a specific reason 2.8x doesn't display the Rigid-Body bounding box shapes in the viewport? 2.7x did this, and it was very helpful. I'm assuming it's intentional and not a bug. ![RB Bounding Box in 2.8x.jpg](https://archive.blender.org/developer/F7789586/RB_Bounding_Box_in_2.8x.jpg) ![RB Bounding Box in 2.7x.jpg](https://archive.blender.org/developer/F7789585/RB_Bounding_Box_in_2.7x.jpg)

Germano Cavalcante commented

2019-10-04 22:14:22 +02:00

In #70505#789829, @Andrewm90 wrote:
On a related note, is there a specific reason 2.8x doesn't display the Rigid-Body bounding box shapes in the viewport? 2.7x did this, and it was very helpful. I'm assuming it's intentional and not a bug.

In fact the shape drawing has been lost.
I don't know exactly what to commit, but probably in the transition to the new viewport.
Please open a new report so that the problem can be correctly addressed.

> In #70505#789829, @Andrewm90 wrote: > On a related note, is there a specific reason 2.8x doesn't display the Rigid-Body bounding box shapes in the viewport? 2.7x did this, and it was very helpful. I'm assuming it's intentional and not a bug. In fact the shape drawing has been lost. I don't know exactly what to commit, but probably in the transition to the new viewport. Please open a new report so that the problem can be correctly addressed.

Andy Sellers commented

2019-10-05 00:26:13 +02:00

Will do, thanks!

Sergej Reich was unassigned by Dalai Felinto

2019-12-23 13:48:15 +01:00

Germano Cavalcante commented

2020-01-27 15:52:54 +01:00

I will mark it as Know Issue since this module is not in active development.
However, this problem needs to be documented.

I will mark it as `Know Issue` since this module is not in active development. However, this problem needs to be documented.

Philipp Oeser removed the

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Rigid-Bodies Colliding Improperly #70505