Weird oscillations in parented rigid body simulation #68183

New Issue

Justas Birgiolas · 2019-08-03T19:20:41+02:00

Justas Birgiolas commented

2019-08-03 19:20:41 +02:00

System Information
Operating system: Windows-10-10.0.16299 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 416.16

Blender Version
Broken: version: 2.81 (sub 1), branch: master, commit date: 2019-08-03 10:22, hash: 5e5cf9ea9f
Worked: 2.79

Short description of error
Weird oscillations in parented rigid body simulation

Exact steps for others to reproduce the error

Start blender, copy-paste the cube, move Cube.001 so they're both next to each other
Make both cubes as rigid bodies
Set Cube type to 'Passive'
Make Cube the parent of Cube.001
Play animation
Expected: Cube.001 falls down

Actual: Cube.001 rapidly oscillates between the starting position and the falling position

untitled.blend

**System Information** Operating system: Windows-10-10.0.16299 64 Bits Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 416.16 **Blender Version** Broken: version: 2.81 (sub 1), branch: master, commit date: 2019-08-03 10:22, hash: `5e5cf9ea9f` Worked: 2.79 **Short description of error** Weird oscillations in parented rigid body simulation **Exact steps for others to reproduce the error** - Start blender, copy-paste the cube, move Cube.001 so they're both next to each other - Make both cubes as rigid bodies - Set Cube type to 'Passive' - Make Cube the parent of Cube.001 - Play animation - Expected: Cube.001 falls down # Actual: Cube.001 rapidly oscillates between the starting position and the falling position [untitled.blend](https://archive.blender.org/developer/F7647462/untitled.blend)

Justas Birgiolas commented

2019-08-03 19:20:41 +02:00

Added subscriber: @justasb

Gabor Horvath commented

2019-08-04 09:23:15 +02:00

Added subscriber: @hgabor47

Gabor Horvath self-assigned this 2019-08-04 09:23:15 +02:00

Gabor Horvath commented

2019-08-04 09:23:15 +02:00

I found this with Rigid Body Constraints. The connected parts oscillate between the orig pos and the cached animate position.
lawnmower_tut.blend

I found this with Rigid Body Constraints. The connected parts oscillate between the orig pos and the cached animate position. [lawnmower_tut.blend](https://archive.blender.org/developer/F7648407/lawnmower_tut.blend)

Philipp Oeser commented

2019-12-18 18:23:48 +01:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2019-12-18 18:23:48 +01:00

Yes, this has problems with the dependency graph [it is producing dependency cycles in 2.8, which is correct, whereas 2.79 somewhat made its way through in a hackish way...]

Dependency cycles for untitled.blend

Dependency cycle detected:
  OBCube.001/Transform Component/TRANSFORM_SIMULATION_INIT() depends on
  OBCube.001/Transform Component/TRANSFORM_EVAL() via 'Transform Eval -> Simulation Init'
  OBCube.001/Transform Component/TRANSFORM_PARENT() via 'Eval'
  OBCube.001/Transform Component/TRANSFORM_LOCAL() via 'ObLocal -> ObParent'
  OBCube.001/Transform Component/TRANSFORM_INIT() via 'Transform Init'
  OBCube/Transform Component/TRANSFORM_FINAL() via 'Parent'
  OBCube/Transform Component/RIGIDBODY_TRANSFORM_COPY() via 'Rigidbody Sync -> Transform Final'
  SCScene/Transform Component/RIGIDBODY_SIM() via 'Rigidbody Sim Eval -> RBO Sync'
  OBCube.001/Transform Component/TRANSFORM_SIMULATION_INIT() via 'Object Transform -> Rigidbody Sim Eval'
Dependency cycle detected:
  OBCube.001/PointCache Component/POINT_CACHE_RESET() depends on
  OBCube.001/Transform Component/TRANSFORM_EVAL() via 'Transform Simulation -> Point Cache'
  OBCube.001/Transform Component/TRANSFORM_PARENT() via 'Eval'
  OBCube.001/Transform Component/TRANSFORM_LOCAL() via 'ObLocal -> ObParent'
  OBCube.001/Transform Component/TRANSFORM_INIT() via 'Transform Init'
  OBCube/Transform Component/TRANSFORM_FINAL() via 'Parent'
  OBCube/Transform Component/RIGIDBODY_TRANSFORM_COPY() via 'Rigidbody Sync -> Transform Final'
  SCScene/Transform Component/RIGIDBODY_SIM() via 'Rigidbody Sim Eval -> RBO Sync'
  OBCube.001/Transform Component/TRANSFORM_SIMULATION_INIT() via 'Object Transform -> Rigidbody Sim Eval'
  OBCube.001/PointCache Component/POINT_CACHE_RESET() via 'Point Cache -> Rigid Body'
Detected 2 dependency cycles

Dependency cycles for lawnmower_tut.blend

Dependency cycle detected:
  OBBlade/Transform Component/RIGIDBODY_TRANSFORM_COPY() depends on
  OBBlade/Transform Component/TRANSFORM_FINAL() via 'RigidBodyConstraint -> RBC.Object_1'
  OBBlade/Transform Component/RIGIDBODY_TRANSFORM_COPY() via 'Rigidbody Sync -> Transform Final'
Dependency cycle detected:
  OBCube/Transform Component/RIGIDBODY_TRANSFORM_COPY() depends on
  OBBlade/Transform Component/TRANSFORM_FINAL() via 'RigidBodyConstraint -> RBC.Object_2'
  OBBlade/Transform Component/RIGIDBODY_TRANSFORM_COPY() via 'Rigidbody Sync -> Transform Final'
  OBblade/Transform Component/TRANSFORM_FINAL() via 'RigidBodyConstraint -> RBC.Object_1'
  OBblade/Transform Component/TRANSFORM_CONSTRAINTS() via 'ObConstraints -> Done'
  OBCube/Transform Component/TRANSFORM_FINAL() via 'Child Of'
  OBCube/Transform Component/RIGIDBODY_TRANSFORM_COPY() via 'Rigidbody Sync -> Transform Final'
Dependency cycle detected:
  OBCube/Transform Component/RIGIDBODY_TRANSFORM_COPY() depends on
  SCScene/Transform Component/RIGIDBODY_SIM() via 'Rigidbody Sim Eval -> RBO Sync'
  OBBlade/Transform Component/TRANSFORM_FINAL() via 'RigidBodyConstraint Transform -> RB Simulation'
  OBBlade/Transform Component/RIGIDBODY_TRANSFORM_COPY() via 'Rigidbody Sync -> Transform Final'
  OBblade/Transform Component/TRANSFORM_FINAL() via 'RigidBodyConstraint -> RBC.Object_1'
  OBblade/Transform Component/TRANSFORM_CONSTRAINTS() via 'ObConstraints -> Done'
  OBCube/Transform Component/TRANSFORM_FINAL() via 'Child Of'
  OBCube/Transform Component/RIGIDBODY_TRANSFORM_COPY() via 'Rigidbody Sync -> Transform Final'
Dependency cycle detected:
  OBBlade/Transform Component/RIGIDBODY_TRANSFORM_COPY() depends on
  SCScene/Transform Component/RIGIDBODY_SIM() via 'Rigidbody Sim Eval -> RBO Sync'
  OBBlade/Transform Component/TRANSFORM_FINAL() via 'RigidBodyConstraint Transform -> RB Simulation'
  OBBlade/Transform Component/RIGIDBODY_TRANSFORM_COPY() via 'Rigidbody Sync -> Transform Final'
Dependency cycle detected:
  OBCube/Transform Component/RIGIDBODY_TRANSFORM_COPY() depends on
  OBblade/Transform Component/TRANSFORM_FINAL() via 'RigidBodyConstraint -> RBC.Object_2'
  OBblade/Transform Component/TRANSFORM_CONSTRAINTS() via 'ObConstraints -> Done'
  OBCube/Transform Component/TRANSFORM_FINAL() via 'Child Of'
  OBCube/Transform Component/RIGIDBODY_TRANSFORM_COPY() via 'Rigidbody Sync -> Transform Final'
Detected 5 dependency cycles

Sooo, dependency cycles are not treated as bugs [unless they are plain wrong -- which doesnt seem to be the case here]
Note that #58044 (Issue with rigid body and modifiers dependent on transform) is related.
Still need to think a bit about passive rigid bodies though [unsure whether a passive rigid bodies transform really depends on Scenes Rigidbody Sim?]...

Yes, this has problems with the dependency graph [it is producing dependency cycles in 2.8, which is correct, whereas 2.79 somewhat made its way through in a hackish way...] Dependency cycles for `untitled.blend` ``` Dependency cycle detected: OBCube.001/Transform Component/TRANSFORM_SIMULATION_INIT() depends on OBCube.001/Transform Component/TRANSFORM_EVAL() via 'Transform Eval -> Simulation Init' OBCube.001/Transform Component/TRANSFORM_PARENT() via 'Eval' OBCube.001/Transform Component/TRANSFORM_LOCAL() via 'ObLocal -> ObParent' OBCube.001/Transform Component/TRANSFORM_INIT() via 'Transform Init' OBCube/Transform Component/TRANSFORM_FINAL() via 'Parent' OBCube/Transform Component/RIGIDBODY_TRANSFORM_COPY() via 'Rigidbody Sync -> Transform Final' SCScene/Transform Component/RIGIDBODY_SIM() via 'Rigidbody Sim Eval -> RBO Sync' OBCube.001/Transform Component/TRANSFORM_SIMULATION_INIT() via 'Object Transform -> Rigidbody Sim Eval' Dependency cycle detected: OBCube.001/PointCache Component/POINT_CACHE_RESET() depends on OBCube.001/Transform Component/TRANSFORM_EVAL() via 'Transform Simulation -> Point Cache' OBCube.001/Transform Component/TRANSFORM_PARENT() via 'Eval' OBCube.001/Transform Component/TRANSFORM_LOCAL() via 'ObLocal -> ObParent' OBCube.001/Transform Component/TRANSFORM_INIT() via 'Transform Init' OBCube/Transform Component/TRANSFORM_FINAL() via 'Parent' OBCube/Transform Component/RIGIDBODY_TRANSFORM_COPY() via 'Rigidbody Sync -> Transform Final' SCScene/Transform Component/RIGIDBODY_SIM() via 'Rigidbody Sim Eval -> RBO Sync' OBCube.001/Transform Component/TRANSFORM_SIMULATION_INIT() via 'Object Transform -> Rigidbody Sim Eval' OBCube.001/PointCache Component/POINT_CACHE_RESET() via 'Point Cache -> Rigid Body' Detected 2 dependency cycles ``` Dependency cycles for `lawnmower_tut.blend` ``` Dependency cycle detected: OBBlade/Transform Component/RIGIDBODY_TRANSFORM_COPY() depends on OBBlade/Transform Component/TRANSFORM_FINAL() via 'RigidBodyConstraint -> RBC.Object_1' OBBlade/Transform Component/RIGIDBODY_TRANSFORM_COPY() via 'Rigidbody Sync -> Transform Final' Dependency cycle detected: OBCube/Transform Component/RIGIDBODY_TRANSFORM_COPY() depends on OBBlade/Transform Component/TRANSFORM_FINAL() via 'RigidBodyConstraint -> RBC.Object_2' OBBlade/Transform Component/RIGIDBODY_TRANSFORM_COPY() via 'Rigidbody Sync -> Transform Final' OBblade/Transform Component/TRANSFORM_FINAL() via 'RigidBodyConstraint -> RBC.Object_1' OBblade/Transform Component/TRANSFORM_CONSTRAINTS() via 'ObConstraints -> Done' OBCube/Transform Component/TRANSFORM_FINAL() via 'Child Of' OBCube/Transform Component/RIGIDBODY_TRANSFORM_COPY() via 'Rigidbody Sync -> Transform Final' Dependency cycle detected: OBCube/Transform Component/RIGIDBODY_TRANSFORM_COPY() depends on SCScene/Transform Component/RIGIDBODY_SIM() via 'Rigidbody Sim Eval -> RBO Sync' OBBlade/Transform Component/TRANSFORM_FINAL() via 'RigidBodyConstraint Transform -> RB Simulation' OBBlade/Transform Component/RIGIDBODY_TRANSFORM_COPY() via 'Rigidbody Sync -> Transform Final' OBblade/Transform Component/TRANSFORM_FINAL() via 'RigidBodyConstraint -> RBC.Object_1' OBblade/Transform Component/TRANSFORM_CONSTRAINTS() via 'ObConstraints -> Done' OBCube/Transform Component/TRANSFORM_FINAL() via 'Child Of' OBCube/Transform Component/RIGIDBODY_TRANSFORM_COPY() via 'Rigidbody Sync -> Transform Final' Dependency cycle detected: OBBlade/Transform Component/RIGIDBODY_TRANSFORM_COPY() depends on SCScene/Transform Component/RIGIDBODY_SIM() via 'Rigidbody Sim Eval -> RBO Sync' OBBlade/Transform Component/TRANSFORM_FINAL() via 'RigidBodyConstraint Transform -> RB Simulation' OBBlade/Transform Component/RIGIDBODY_TRANSFORM_COPY() via 'Rigidbody Sync -> Transform Final' Dependency cycle detected: OBCube/Transform Component/RIGIDBODY_TRANSFORM_COPY() depends on OBblade/Transform Component/TRANSFORM_FINAL() via 'RigidBodyConstraint -> RBC.Object_2' OBblade/Transform Component/TRANSFORM_CONSTRAINTS() via 'ObConstraints -> Done' OBCube/Transform Component/TRANSFORM_FINAL() via 'Child Of' OBCube/Transform Component/RIGIDBODY_TRANSFORM_COPY() via 'Rigidbody Sync -> Transform Final' Detected 5 dependency cycles ``` Sooo, dependency cycles are not treated as bugs [unless they are plain wrong -- which doesnt seem to be the case here] Note that #58044 (Issue with rigid body and modifiers dependent on transform) is related. Still need to think a bit about **passive** rigid bodies though [unsure whether a passive rigid bodies transform really depends on Scenes Rigidbody Sim?]...

Philipp Oeser commented

2019-12-18 18:38:00 +01:00

Closed as duplicate of #69065

Philipp Oeser closed this issue

2019-12-18 18:38:00 +01:00

Philipp Oeser commented

2019-12-18 18:38:10 +01:00

Actually, we have another report about this, see #69065 (Bug on Rigid Body Simulation when an object is parented to another), will merge these reports...

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Weird oscillations in parented rigid body simulation #68183

Actual: Cube.001 rapidly oscillates between the starting position and the falling position