Cloth disappears on frame 2+. #78113

New Issue

KingKilo · 2020-06-21T22:32:49+02:00

KingKilo commented

2020-06-21 22:32:49 +02:00

System Information
Operating system: Windows 10 Home - 10.0.18362

NVIDIA GeForce GTX 1080 Ti
Intel(R) Core(TM) i7-7800X CPU @ 3.50GHz
32GB RAM

Blender Version
Broken: 2.83
Worked: newest version of Blender that worked as expected

Short description of error
I've made a few flags, to be fluttering in the wind.
However, when I play my animation (before or after baking all dynamics) most of them just disappear. (often all of them)
Others just absolutely spazz out'. As if some unknown force is scrambling them.

How to replicate.
Make a 2m x 1m plane.
Subdivide up to 60x cuts
Add cloth modifier.
Object collisions
Self Collisions

Add solidify modifier.
Add Subdivision modifier.

Top left 3 and bottom left 3 vertexes are added to vertex group. (add to shape)

Add wind > 1500 strength.

Press play

Flags.blend

**System Information** Operating system: Windows 10 Home - 10.0.18362 NVIDIA GeForce GTX 1080 Ti Intel(R) Core(TM) i7-7800X CPU @ 3.50GHz 32GB RAM **Blender Version** Broken: 2.83 Worked: newest version of Blender that worked as expected **Short description of error** I've made a few flags, to be fluttering in the wind. However, when I play my animation (before or after baking all dynamics) most of them just disappear. (often all of them) Others just absolutely spazz out'. As if some unknown force is scrambling them. **How to replicate.** Make a 2m x 1m plane. Subdivide up to 60x cuts Add cloth modifier. Object collisions Self Collisions Add solidify modifier. Add Subdivision modifier. Top left 3 and bottom left 3 vertexes are added to vertex group. (add to shape) Add wind > 1500 strength. *Press play* [Flags.blend](https://archive.blender.org/developer/F8635651/Flags.blend)

KingKilo commented

2020-06-21 22:32:49 +02:00

Added subscriber: @KingKilo

KingKilo commented

2020-06-22 11:47:09 +02:00

Little self-update.

When the flags are rotated 90 degrees on the X axis, they seem to always fail. But when I put it on 89 or 91, it works much better.
Still buggy from time to time, with flags going absolutely ham, or disappearing, but not nearly as much.

Little self-update. When the flags are rotated 90 degrees on the X axis, they seem to always fail. But when I put it on 89 or 91, it works much better. Still buggy from time to time, with flags going absolutely ham, or disappearing, but not nearly as much.

Germano Cavalcante commented

2020-06-24 18:13:41 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2020-06-24 18:13:41 +02:00

Changed status from 'Needs Triage' to: 'Confirmed'

Germano Cavalcante commented

2020-06-24 18:13:41 +02:00

It seems related to the Self Collision.
Maybe the distance for self collision is not well configured?

It is strange that in the file some simulations work and others do not, despite having the same settings.

This does indeed appear to be a bug.

I cannot reproduce this problem with previous versions of blender. However, the simulation takes much longer in 2.80 - 2.82.

It seems related to the `Self Collision`. Maybe the distance for self collision is not well configured? It is strange that in the file some simulations work and others do not, despite having the same settings. This does indeed appear to be a bug. I cannot reproduce this problem with previous versions of blender. However, the simulation takes much longer in 2.80 - 2.82.

Jacques Lucke commented

2020-08-06 14:15:01 +02:00

Added subscriber: @JacquesLucke

Jacques Lucke commented

2020-08-06 14:15:01 +02:00

Can we get a smaller/simpler example .blend file that simulates a bit faster. That would make fixing this issue easier.

Germano Cavalcante commented

2020-08-06 20:35:03 +02:00

I couldn't make a good simplified file since the mesh that presents the problem seems to be quite random.
But putting a breakpoint in the cloth_selfcollision function I realized that, in the first interaction, the distance calculated by compute_collision_point_tri_tri is 0.0f. Which should be impossible since none of the triangles are really intersecting.
So I believe that the first step in solving this problem is finding out what causes the wrong result in compute_collision_point_tri_tri.

I can investigate this better next week.

I couldn't make a good simplified file since the mesh that presents the problem seems to be quite random. But putting a breakpoint in the `cloth_selfcollision` function I realized that, in the first interaction, the distance calculated by `compute_collision_point_tri_tri` is `0.0f`. Which should be impossible since none of the triangles are really intersecting. So I believe that the first step in solving this problem is finding out what causes the wrong result in `compute_collision_point_tri_tri`. I can investigate this better next week.

blender-admin commented

2020-08-10 17:05:37 +02:00

This issue was referenced by c0340ec893

This issue was referenced by c0340ec89393055bbb0ba0432b9edb5d70b3711c

Germano Cavalcante commented

2020-08-10 17:06:30 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Germano Cavalcante closed this issue

2020-08-10 17:06:30 +02:00

Germano Cavalcante self-assigned this 2020-08-10 17:06:30 +02:00

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Cloth disappears on frame 2+. #78113