Collision between convex hull and triangle mesh causing slow fps in bge #46752

New Issue

Ian · 2015-11-12T21:09:13+01:00

Ian commented

2015-11-12 21:09:13 +01:00

2.6b Build. Collisions between and triangle mesh physics objects are not respecting the collision radius values. This is leading to unpredictable physics simulations compared to 2.74 and severely decreased frame rates. Example file (attached) runs at 32 fps regardless of the a) emitter running b) the number of colliding objects added using spacebar. In 2.74 the added objects (via spacebar) make their way cleanly from top to bottom whilst bouncing off the included obstacles freely.

Tested on 2.74 release version and 2.75 official daily build from 10/11/2015 19:35 Hash 8c84a18
Machine: PC Windows 10 Pro. I7 with geforce GT 540M.tedhbug276.blend

2.6b Build. Collisions between and triangle mesh physics objects are not respecting the collision radius values. This is leading to unpredictable physics simulations compared to 2.74 and severely decreased frame rates. Example file (attached) runs at 32 fps regardless of the a) emitter running b) the number of colliding objects added using spacebar. In 2.74 the added objects (via spacebar) make their way cleanly from top to bottom whilst bouncing off the included obstacles freely. Tested on 2.74 release version and 2.75 official daily build from 10/11/2015 19:35 Hash 8c84a18 Machine: PC Windows 10 Pro. I7 with geforce GT 540M.[tedhbug276.blend](https://archive.blender.org/developer/F254198/tedhbug276.blend)

Ian commented

2015-11-12 21:09:13 +01:00

Changed status to: 'Open'

Ian commented

2015-11-12 21:09:13 +01:00

Added subscriber: @iansmith

Ian commented

2015-11-13 05:18:50 +01:00

Edit to the above description. It was tested today on the latest 2.76 daily build and the problem still exists.

Porteries Tristan commented

2015-11-13 19:37:56 +01:00

Added subscriber: @panzergame

Porteries Tristan commented

2015-11-13 19:37:56 +01:00

Confirm the bug

Ulysse Martin commented

2015-11-13 21:41:54 +01:00

Added subscriber: @you.le

Ulysse Martin commented

2015-11-13 21:41:54 +01:00

Hi, we can notice a performance/behavior change issue since this commit: https://developer.blender.org/rB909d3228b1d0254888d0c97d269e9ab2e315dba9

Porteries Tristan commented

2015-11-13 22:16:38 +01:00

@iansmith: You can set margin to 0 to solve all of your issues.

Why ?
The commit 909d3228b1 introduced the support of margin for physique shapes based on triangles.

What's wrong ?

Apparently Bullet create a big slow down when it must compute with a shape's margin.
It's my fault, i forgot to set margin to 0 in the compatibility file when i commited this support, now is to late (commited in 2.75)...

Sorry for the disturbance.
If it works for you close the bug them.

@iansmith: You can set margin to 0 to solve all of your issues. `Why ?` The commit 909d3228b1 introduced the support of margin for physique shapes based on triangles. `What's wrong ?` 1) Apparently Bullet create a big slow down when it must compute with a shape's margin. 2) It's my fault, i forgot to set margin to 0 in the compatibility file when i commited this support, now is to late (commited in 2.75)... Sorry for the disturbance. If it works for you close the bug them.

Ian commented

2015-11-13 22:48:29 +01:00

Hi, if I change the collision bounds of my static triangle mesh from '0.4' to '0.1' and reduce the dynamic objects convex hull 'Radius' from '1.0' to '0.1' (along with a collision bounds margin to '0.0') the original behaviour and performance is restored.
I'm happy to close it if this is an acceptable/intended change between versions rather than a bug. Is this the case?

Hi, if I change the collision bounds of my static triangle mesh from '0.4' to '0.1' and reduce the dynamic objects convex hull 'Radius' from '1.0' to '0.1' (along with a collision bounds margin to '0.0') the original behaviour and performance is restored. I'm happy to close it if this is an acceptable/intended change between versions rather than a bug. Is this the case?

Ian commented

2015-11-15 22:26:36 +01:00

Changed status from 'Open' to: 'Resolved'

Ian closed this issue

2015-11-15 22:26:36 +01:00

Ian self-assigned this 2015-11-15 22:26:36 +01:00

Ian commented

2015-11-15 22:26:36 +01:00

Hi, as this can be worked around it will be closed.

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Collision between convex hull and triangle mesh causing slow fps in bge #46752