Page MenuHome

PhysicsProject
ActivePublic

Details

Description

Physics simulation systems including rigid bodies, cloth, softbodies, smoke fluids and particles.

Developers

Bullet: @Erwin Coumans (erwin)
Rigid Body: @Sergej Reich (sergof)
Cloth: @Daniel Genrich (genscher)
Smoke: @Miika Hamalainen (miikah) @Daniel Genrich (genscher)
Fluids: @Daniel Genrich (genscher) @Nils Thuerey (n_t)
Particles: @Janne Karhu (jhk) @Lukas Toenne (lukastoenne)
Softbody: @Jens Ole Wund(bjornmose) (bjornmose)

Recent Activity

Yesterday

Sergey Sharybin (sergey) merged T63761: hair particles not updated if the parent is an active rigid body object into T58044: Issue with adding hair to rigid body.
Thu, Apr 25, 12:41 PM · BF Blender: 2.8, Physics

Tue, Apr 23

Nils Thuerey (n_t) added a comment to T59995: Mantaflow Review.

@Brecht Van Lommel (brecht) Okay, yes - the GIL seems to be unproblematic so far. It could make the UI somewhat unresponsive when baking large sims, though. The new node system notes look interesting. I think for mantaflow it would neat to go for the "everything-nodes" direction, where a node graph would define the data flow of the simulation. This could then use a python back-end, or directly hook into the mantaflow functions (the functions that are exposes to python are the crucial ones that ideally would also be available as nodes). It's definitely a good point to keep in mind.

Tue, Apr 23, 1:53 PM · Physics, BF Blender

Thu, Apr 18

Brecht Van Lommel (brecht) added a comment to T59995: Mantaflow Review.

Ok. The main concern is not so much that it's slow for fluid simulation by itself, but if multiple performance sensitive areas use Python it does become a problem to have these global locks. If this is how the Mantaflow API works and it's a big burden to use C++ instead it seems acceptable.

Thu, Apr 18, 5:00 PM · Physics, BF Blender
Nils Thuerey (n_t) added a comment to T59995: Mantaflow Review.

@Brecht Van Lommel (brecht) Good question, to add to sebbas comments, there are a few reasons for the python bindings: a first mundane one is that that's how the mantaflow solver worked originally, and it would have been a lot more work to switch to C/C++ bindings. Also, the performance impact is negligible, as mantaflow provides all the solver building blocks via python, but each of the steps is quite expensive. So there are no low-level operations in python (e.g. access to grid cells), but just a small number of calls to high level functions that typically make several passes over the full grid.

Thu, Apr 18, 4:19 PM · Physics, BF Blender
joel heethaar (joel_nl) updated subscribers of T59995: Mantaflow Review.

There's a pull request from David Ullmann extending the NOPYTHON option.

Thu, Apr 18, 11:16 AM · Physics, BF Blender
Sebastián Barschkis (sebbas) added a comment to T59995: Mantaflow Review.

@Brecht Van Lommel (brecht) Right now the only way to access all Mantaflow functions is through Python. In terms of performance I wouldn't say that this is an issue. Once the Manta solver acquires the GIL it will compute one "step" and only once completed release it. The time between steps where other resources (like the UI) can acquire the GIL and Manta has to wait for it would be the only delay during a bake job. This delay is negligible from my experience unless there are other resources that could block the GIL for a very long time.

Thu, Apr 18, 9:57 AM · Physics, BF Blender
Sebastián Barschkis (sebbas) added a comment to T59995: Mantaflow Review.

@Nils Thuerey (n_t) Yes, you're right. Those lines won't be needed in the future anymore. Will remove them.

Thu, Apr 18, 9:19 AM · Physics, BF Blender

Wed, Apr 17

Brecht Van Lommel (brecht) added a comment to T59995: Mantaflow Review.

Can someone remind me why this is integrated through Python rather than C++, and how much work it would to change it to C++?

Wed, Apr 17, 11:37 AM · Physics, BF Blender
Nils Thuerey (n_t) added a comment to T59995: Mantaflow Review.

@Sebastián Barschkis (sebbas) - I noticed the exported python scene has a few lines at the top for OS/multi-processing checks that don't seem to be used or necessary. (from "withMP ... up to VARIABLES", ca. lines 8 to 18). Those could be removed, right?

Wed, Apr 17, 9:46 AM · Physics, BF Blender

Tue, Apr 16

Brecht Van Lommel (brecht) added a comment to T63606: Soft Body bake doesn't delete in "Disk Cache" mode.

@Ulysse Martin (youle), thanks for the video. What I tested is that when I'm at e.g. frame 50 and press Delete Bake then, I would expect it to remove all results from the physics sim, and you'd have to go back to frame 0 to see the result. That doesn't happen here.

Tue, Apr 16, 4:43 PM · Physics, BF Blender
Ulysse Martin (youle) added a comment to T63606: Soft Body bake doesn't delete in "Disk Cache" mode.

I join a .gif video to show before and after applying the patch on my computer:

Tue, Apr 16, 4:35 PM · Physics, BF Blender
Brecht Van Lommel (brecht) added a comment to T63606: Soft Body bake doesn't delete in "Disk Cache" mode.

This patch doesn't seem to do anything for me.

Tue, Apr 16, 4:00 PM · Physics, BF Blender
Sebastian Parborg (zeddb) assigned T63606: Soft Body bake doesn't delete in "Disk Cache" mode to Sergey Sharybin (sergey).
Tue, Apr 16, 11:41 AM · Physics, BF Blender

Mon, Apr 15

Ulysse Martin (youle) added a comment to T63606: Soft Body bake doesn't delete in "Disk Cache" mode.

I can confirm an issue with delete bake action.

Mon, Apr 15, 12:07 AM · Physics, BF Blender

Sun, Apr 14

Casey (BagelCo) added a project to T63606: Soft Body bake doesn't delete in "Disk Cache" mode: Physics.
Sun, Apr 14, 10:50 PM · Physics, BF Blender
Emmanuel A. Briones (eabriones) removed a watcher for Physics: Emmanuel A. Briones (eabriones).
Sun, Apr 14, 6:55 AM
Emmanuel A. Briones (eabriones) added a watcher for Physics: Emmanuel A. Briones (eabriones).
Sun, Apr 14, 6:55 AM

Mon, Apr 8

Nils Thuerey (n_t) added a comment to T59995: Mantaflow Review.

Hi everyone, great to see the manta integration being re-revived! @Sebastián Barschkis (sebbas) thanks for the large patch collection. I just checked out and tried the revised diff "from scratch". Works nicely on my MAC. The sims also run through without problem (I tested based on the quick-smoke and quick-liquid setups). So I think this patch looks good, overall. There are some obvious next steps, like removing the old liquid/smoke modifiers, and cleaning up the code, but I think this would be better to address once the manta code is integrated.

Mon, Apr 8, 10:09 AM · Physics, BF Blender

Sun, Apr 7

Sebastián Barschkis (sebbas) added a comment to T59995: Mantaflow Review.

@Bastien Montagne (mont29) Yes, that's definitely a good idea. I just updated the diffs (now it's branched from the 2.8 "master") and also synced it with the fluid-mantaflow branch which can be used for test builds. From here we could now get the review rolling.

Sun, Apr 7, 7:42 PM · Physics, BF Blender

Thu, Apr 4

Benjamin Meyer (Anvilarion) added inline comments to D4591: Correctly display number of cached frames during simulation with negative start frame.
Thu, Apr 4, 6:48 PM · BF Blender: Staging, Physics
Sergey Sharybin (sergey) closed D4636: Fix: Erratic collision response when using constraints on colliders.
Thu, Apr 4, 11:06 AM · Physics
Sergey Sharybin (sergey) added inline comments to D4591: Correctly display number of cached frames during simulation with negative start frame.
Thu, Apr 4, 10:20 AM · BF Blender: Staging, Physics
Mal Duffin (mal_cando) added a comment to T58044: Issue with adding hair to rigid body.

Hi Sergey,

Thu, Apr 4, 9:41 AM · BF Blender: 2.8, Physics
Sergey Sharybin (sergey) claimed T58044: Issue with adding hair to rigid body.

Would need to have a closer look, but could be caused by the change in the evaluation order of rigid body, similar to T63028.

Thu, Apr 4, 9:36 AM · BF Blender: 2.8, Physics

Wed, Apr 3

Brecht Van Lommel (brecht) edited reviewers for D4636: Fix: Erratic collision response when using constraints on colliders, added: Sergey Sharybin (sergey); removed: Physics.
Wed, Apr 3, 7:14 PM · Physics
Brecht Van Lommel (brecht) edited reviewers for D4591: Correctly display number of cached frames during simulation with negative start frame, added: Sergey Sharybin (sergey); removed: Sergej Reich (sergof).
Wed, Apr 3, 7:13 PM · BF Blender: Staging, Physics
Benjamin Meyer (Anvilarion) created D4636: Fix: Erratic collision response when using constraints on colliders.
Wed, Apr 3, 2:30 PM · Physics
Sebastian Parborg (zeddb) assigned T63238: Soft body simulation that previously work in 2.79 does not work in 2.8 to Sergey Sharybin (sergey).

I'm getting this error printed in the terminal (probably related to this issue):
ERROR (bke.rigidbody): /home/zed/prog/blender/source/blender/blenkernel/intern/rigidbody.c:299 rigidbody_get_shape_convexhull_from_mesh: no vertices to define Convex Hull collision shape with

Wed, Apr 3, 12:45 PM · Physics, BF Blender: 2.8, BF Blender
Michael Lee (michaellee8) added projects to T63238: Soft body simulation that previously work in 2.79 does not work in 2.8: BF Blender: 2.8, Physics.
Wed, Apr 3, 9:04 AM · Physics, BF Blender: 2.8, BF Blender

Tue, Apr 2

Brecht Van Lommel (brecht) lowered the priority of T54108: Child Of vertex group fails when controled by Particle System from Confirmed, Medium to Confirmed, Low.

Not sure about the right behavior, would consider quite low priority.

Tue, Apr 2, 7:12 PM · Physics, Animation, BF Blender

Sun, Mar 31

Benjamin Meyer (Anvilarion) updated the diff for D4591: Correctly display number of cached frames during simulation with negative start frame.
Sun, Mar 31, 5:49 PM · BF Blender: Staging, Physics
Benjamin Meyer (Anvilarion) added a reviewer for D4591: Correctly display number of cached frames during simulation with negative start frame: Brecht Van Lommel (brecht).
Sun, Mar 31, 5:04 PM · BF Blender: Staging, Physics

Thu, Mar 28

Philipp Oeser (lichtwerk) placed T54108: Child Of vertex group fails when controled by Particle System up for grabs.

Checked this again and atm it just averages positions and normals of participating verts.
A rotation is derived from the resulting averaged normal alone - thus not being 'stable'.

Thu, Mar 28, 8:52 PM · Physics, Animation, BF Blender

Wed, Mar 27

Philipp Oeser (lichtwerk) added a comment to T62980: Animated ABC Won't Collide With Fluid Simulation.

Havent actually checked it, and it feels like swapping mesh datablocks in a framechange handler is not the best solution, but would it help getting the evaluated object?

Wed, Mar 27, 10:10 PM · Physics, Alembic, BF Blender
Atomic (atomic) added a comment to T62980: Animated ABC Won't Collide With Fluid Simulation.

So why can't I fetch the mesh data block, from the .abc animation, in a frame change?
Shouldn't the Mesh Sequence Cache modifier correctly present the current mesh data block, to the API, for the frame it is displaying?
Why does the frame change code fail?

Wed, Mar 27, 1:55 PM · Physics, Alembic, BF Blender
Philipp Oeser (lichtwerk) added projects to T62980: Animated ABC Won't Collide With Fluid Simulation: Alembic, Physics.
Wed, Mar 27, 11:23 AM · Physics, Alembic, BF Blender

Mar 26 2019

Brecht Van Lommel (brecht) closed T58171: Crash when using over 2 particles systems as Resolved.

Confirmed in older version, but appears to be fixed now.

Mar 26 2019, 1:50 PM · BF Blender, Physics

Mar 25 2019

Benjamin Meyer (Anvilarion) created D4591: Correctly display number of cached frames during simulation with negative start frame.
Mar 25 2019, 6:59 PM · BF Blender: Staging, Physics

Mar 21 2019

Bastien Montagne (mont29) closed T52873: Vertex Weight Proximity breaks Rigid Body simulation as Archived.

Yes, this is indeed a chicken & egg issue (and yes, it also happens in 2.7x). Guess we can close that as known limitation for now, then.

Mar 21 2019, 9:50 AM · Modifiers, Physics, BF Blender

Mar 20 2019

Sergey Sharybin (sergey) added a comment to T52873: Vertex Weight Proximity breaks Rigid Body simulation.

But same happens in 2.7?
This sounds like a feedback loop between rigid body simulation which needs geometry for the collisions, but geometry needs transform for modifier stack. While we can avoid some dependency cycles here, the order of updates might be wrong from users perspective. And the only user-controllable solution here would be to go node based.

Mar 20 2019, 9:24 PM · Modifiers, Physics, BF Blender
Bastien Montagne (mont29) added a comment to T52873: Vertex Weight Proximity breaks Rigid Body simulation.

Deg warning about DEG_OB_COMP_GEOMETRY relation is now fixed, but the rigid body simulation remains completely broken in 2.8 currently here (neither of the two displace modifiers work, only really moving red object works currently).

Mar 20 2019, 9:15 PM · Modifiers, Physics, BF Blender
Mal Duffin (mal_cando) added a comment to T58044: Issue with adding hair to rigid body.

@Sergey Sharybin (sergey) - I see you just fixed another issue with rigid bodies and particles, could you have a look at this one too?

Mar 20 2019, 9:10 PM · BF Blender: 2.8, Physics
Bastien Montagne (mont29) added a comment to T52873: Vertex Weight Proximity breaks Rigid Body simulation.

Using an empty (or center point of any object) is a valid usecase of this modifier, will check on those relations tagging.

Mar 20 2019, 8:45 PM · Modifiers, Physics, BF Blender
Sergey Sharybin (sergey) reassigned T52873: Vertex Weight Proximity breaks Rigid Body simulation from Sergey Sharybin (sergey) to Bastien Montagne (mont29).

The issue in code i saw was related on a fake dependency cycle, which is now fixed in rB099a4104788.
Now i can open the file and there is a playback going on.

Mar 20 2019, 4:42 PM · Modifiers, Physics, BF Blender
Victor V Green II (Sleeper_G) closed T62628: explosions as Resolved.

I fixed the issue. I just had to turn my quality steps down to 2.

Mar 20 2019, 1:56 PM · Rendering, Platform: Windows, BF Blender: 2.8, Physics, Eevee

Mar 19 2019

Brecht Van Lommel (brecht) closed T58233: Crash selecting path as render as type in particle system. as Resolved.

I believe macOS particle drawing crashes were fixed, if it's still an issue we can reopen the report.

Mar 19 2019, 10:57 AM · BF Blender, Physics

Mar 17 2019

Victor V Green II (Sleeper_G) edited projects for T62628: explosions, added: BF Blender: 2.8, Platform: Windows, Rendering; removed BF Blender.

I don't know what to expect here. Will someone be explaining to me what what to do about mt issue?

Mar 17 2019, 10:00 PM · Rendering, Platform: Windows, BF Blender: 2.8, Physics, Eevee

Mar 16 2019

Brecht Van Lommel (brecht) placed T62628: explosions up for grabs.
Mar 16 2019, 12:32 AM · Rendering, Platform: Windows, BF Blender: 2.8, Physics, Eevee
Victor V Green II (Sleeper_G) claimed T62628: explosions.
Mar 16 2019, 12:23 AM · Rendering, Platform: Windows, BF Blender: 2.8, Physics, Eevee

Mar 15 2019

Sergey Sharybin (sergey) reassigned T51214: Dynamic Paint Works Only in Viewport Render from Sergey Sharybin (sergey) to Clément Foucault (fclem).

It works in LookDev mode.

Mar 15 2019, 12:52 PM · Physics, BF Blender