Animated Mesh renders correctly in Eevee, Workbench, but not Cycles #101051

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Ward Darcey · 2022-09-14T04:40:13+02:00

Ward Darcey commented

2022-09-14 04:40:13 +02:00

Please find related files - for V3.3 - The purple mesh is driven by the armature and wiggles exactly as I would expect. It has two mesh deform modifiers on it, one on each end; the cage objects for those modifiers are the two green things. They are also working as expected. The targets for the cages are the two empties, and they copy the x-location of the two blue cubes; and these are in turn driven off the Z rotation of the two red cubes through transformation constraint. This all works exactly as expected.

So, what I have got is an animated purple object, with mesh deforms operating on each end, and these are ultimately driven off the rotation of the two red cubes, which could be a noise modifier or anything else - I've tried it & any source driving the red cubes seems to progress just fine right through to the purple mesh, all movements render out, no problems so far.
BUT - if I try & use physics action to drive this setup . . . see below.
I have two small triangle objects on each end, with softbody physics, all flapping away with the animation, with two small yellow cubes parented to them, to pick up the z-rotation of the triangles as they bounce around. (I have done this because I cannot pick up a z-rotation directly off the triangles - I don't know why). This works fine.
OK - The problem arises when I use the z-rotation off the yellow cubes to drive the blue cubes x-direction. It looks like it is working in solid mode, but the deforms on the purple mesh will not render out in Cycles. It will however render out in Eevee or Workbench.

I have spent a few days trying to isolate the problem here, & it looks to me like there is rotation data not getting into the Cycles render engine, when it is copied from the yellow cubes, which are under the action of softbody Physics. This data does however, get to Cycles, Eevee & Workbench when the source of the rotation is anything else. So it seems there is something not being copied out of the physics activity of those yellow cubes into Cycles at render time. I have experimented with different spaces etc, tried all the settings I can but with no success.

I suspect there is a bug here, & this is something I used to do quite often in Blender 2.79 with no problems. This has always been one of my methods to add physics to mesh surfaces.
I have determined that it doesn't make any difference whether I use the graphics card or the CPU to do the rendering.
If you can check this out, it would be good to get it working again, thanks.system-info.txt

Two_Mesh_Def_Mods_01.blend simple as possible).

Please find related files - for V3.3 - The purple mesh is driven by the armature and wiggles exactly as I would expect. It has two mesh deform modifiers on it, one on each end; the cage objects for those modifiers are the two green things. They are also working as expected. The targets for the cages are the two empties, and they copy the x-location of the two blue cubes; and these are in turn driven off the Z rotation of the two red cubes through transformation constraint. This all works exactly as expected. So, what I have got is an animated purple object, with mesh deforms operating on each end, and these are ultimately driven off the rotation of the two red cubes, which could be a noise modifier or anything else - I've tried it & any source driving the red cubes seems to progress just fine right through to the purple mesh, all movements render out, no problems so far. BUT - if I try & use physics action to drive this setup . . . see below. I have two small triangle objects on each end, with softbody physics, all flapping away with the animation, with two small yellow cubes parented to them, to pick up the z-rotation of the triangles as they bounce around. (I have done this because I cannot pick up a z-rotation directly off the triangles - I don't know why). This works fine. OK - The problem arises when I use the z-rotation off the yellow cubes to drive the blue cubes x-direction. It looks like it is working in solid mode, but the deforms on the purple mesh will not render out in Cycles. It will however render out in Eevee or Workbench. I have spent a few days trying to isolate the problem here, & it looks to me like there is rotation data not getting into the Cycles render engine, when it is copied from the yellow cubes, which are under the action of softbody Physics. This data does however, get to Cycles, Eevee & Workbench when the source of the rotation is anything else. So it seems there is something not being copied out of the physics activity of those yellow cubes into Cycles at render time. I have experimented with different spaces etc, tried all the settings I can but with no success. I suspect there is a bug here, & this is something I used to do quite often in Blender 2.79 with no problems. This has always been one of my methods to add physics to mesh surfaces. I have determined that it doesn't make any difference whether I use the graphics card or the CPU to do the rendering. If you can check this out, it would be good to get it working again, thanks.[system-info.txt](https://archive.blender.org/developer/F13490670/system-info.txt) [Two_Mesh_Def_Mods_01.blend](https://archive.blender.org/developer/F13490669/Two_Mesh_Def_Mods_01.blend) simple as possible).

Ward Darcey commented

2022-09-14 04:40:13 +02:00

Added subscriber: @didactic

Evan Wilson commented

2022-09-14 09:48:04 +02:00

Added subscriber: @EAW

Evan Wilson self-assigned this 2022-09-14 09:48:04 +02:00

Evan Wilson commented

2022-09-14 09:48:04 +02:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Evan Wilson commented

2022-09-14 09:48:04 +02:00

Hi @didactic. I rendered this in Cycles in the current master 3.4 and 3.3.
To me, the renders appear identical to the viewport.
Could you upload a recording of the issue?

3.4
0001-0050.mp4
3.3
0001-0050.mp4

Hi @didactic. I rendered this in Cycles in the current master 3.4 and 3.3. To me, the renders appear identical to the viewport. Could you upload a recording of the issue? 3.4 [0001-0050.mp4](https://archive.blender.org/developer/F13491260/0001-0050.mp4) 3.3 [0001-0050.mp4](https://archive.blender.org/developer/F13491304/0001-0050.mp4)

Ward Darcey commented

2022-09-14 12:41:56 +02:00

Yes, here's 3 .mkv's named as per render engine. I changed nothing but the render engine to generate these. The wobbles on the ends show in the viewport, in the Eevee output & the Workbench output, but not with Cycles.
I've tried coupling the physics motion using drivers in place of constraints, & had the same results; so it seems always that everything else is fine, but Cycles doesn't get the mesh deforms.Render_with_Workbench.mkv

Render_with_Eevee.mkv

Render_with_Cycles.mkv

Yes, here's 3 .mkv's named as per render engine. I changed nothing but the render engine to generate these. The wobbles on the ends show in the viewport, in the Eevee output & the Workbench output, but not with Cycles. I've tried coupling the physics motion using drivers in place of constraints, & had the same results; so it seems always that everything else is fine, but Cycles doesn't get the mesh deforms.[Render_with_Workbench.mkv](https://archive.blender.org/developer/F13491797/Render_with_Workbench.mkv) [Render_with_Eevee.mkv](https://archive.blender.org/developer/F13491798/Render_with_Eevee.mkv) [Render_with_Cycles.mkv](https://archive.blender.org/developer/F13491799/Render_with_Cycles.mkv)

Evan Wilson commented

2022-09-19 06:52:59 +02:00

Thank you for the update @didactic.

There are two dependency cycles reported in the console.
Two Errors are also reported in the console involving both MeshDeform Modifiers.
You can show the console by going Window->Toggle System Console
You can also see this by starting Blender with blender_debug_log.cmd and reading the generated log.
When rendering with Cycles, the dependency cycles and modifier errors are reported every frame.
With EEVEE, the dependency cycles are reported 3 times, and the modifier error only once.
When rendering, Cycles rebuilds it's dependency graph every frame (as far as I am aware), while EEVEE and Workbench (and the Cycle's viewport) are able to use parts of the dependency graph from the previous frame.

Reading about the Mesh Deform Modifier, I am surprised to see that this is only an error in the Cycles rendered movie, as the cage mesh is intended to surround the mesh it is deforming, which it doesn't do in this file.

Dependency cycle detected:
  OBCylinder/Geometry Component/GEOMETRY_EVAL() depends on
  OBCube_B/Geometry Component/GEOMETRY_EVAL() via 'Mesh Deform Modifier'
  OBEmpty.B/Transform Component/TRANSFORM_FINAL() via 'Cast Modifier'
  OBEmpty.B/Transform Component/TRANSFORM_CONSTRAINTS() via 'ObConstraints -> Done'
  OBCube.B/Transform Component/TRANSFORM_FINAL() via 'Copy Location'
  OBCube.B/Transform Component/TRANSFORM_CONSTRAINTS() via 'ObConstraints -> Done'
  OBCube.003/Transform Component/TRANSFORM_FINAL() via 'Transformation'
  OBCube.003/Transform Component/TRANSFORM_SIMULATION_INIT() via 'Simulation -> Final Transform'
  OBCube.003/Transform Component/TRANSFORM_EVAL() via 'Transform Eval -> Simulation Init'
  OBCube.003/Transform Component/TRANSFORM_PARENT() via 'Eval'
  OBCube.003/Transform Component/TRANSFORM_LOCAL() via 'ObLocal -> ObParent'
  OBCube.003/Transform Component/TRANSFORM_INIT() via 'Transform Init'
  OBPlane.001/Geometry Component/GEOMETRY_EVAL() via 'Vertex Parent'
  OBPlane.001/Geometry Component/GEOMETRY_EVAL_INIT() via 'Object Geometry UberEval'
  OBPlane.001/Transform Component/TRANSFORM_FINAL() via 'SoftBody Modifier'
  OBPlane.001/Transform Component/TRANSFORM_SIMULATION_INIT() via 'Simulation -> Final Transform'
  OBPlane.001/Transform Component/TRANSFORM_EVAL() via 'Transform Eval -> Simulation Init'
  OBPlane.001/Transform Component/TRANSFORM_PARENT() via 'Eval'
  OBPlane.001/Transform Component/TRANSFORM_LOCAL() via 'ObLocal -> ObParent'
  OBPlane.001/Transform Component/TRANSFORM_INIT() via 'Transform Init'
  OBCylinder/Geometry Component/GEOMETRY_EVAL() via 'Vertex Parent'
Dependency cycle detected:
  OBCylinder/Geometry Component/GEOMETRY_EVAL() depends on
  OBCube_A/Geometry Component/GEOMETRY_EVAL() via 'Mesh Deform Modifier'
  OBEmpty.A/Transform Component/TRANSFORM_FINAL() via 'Cast Modifier'
  OBEmpty.A/Transform Component/TRANSFORM_CONSTRAINTS() via 'ObConstraints -> Done'
  OBCube.A/Transform Component/TRANSFORM_FINAL() via 'Copy Location'
  OBCube.A/Transform Component/TRANSFORM_CONSTRAINTS() via 'ObConstraints -> Done'
  OBCube.004/Transform Component/TRANSFORM_FINAL() via 'Transformation'
  OBCube.004/Transform Component/TRANSFORM_SIMULATION_INIT() via 'Simulation -> Final Transform'
  OBCube.004/Transform Component/TRANSFORM_EVAL() via 'Transform Eval -> Simulation Init'
  OBCube.004/Transform Component/TRANSFORM_PARENT() via 'Eval'
  OBCube.004/Transform Component/TRANSFORM_LOCAL() via 'ObLocal -> ObParent'
  OBCube.004/Transform Component/TRANSFORM_INIT() via 'Transform Init'
  OBPlane/Geometry Component/GEOMETRY_EVAL() via 'Vertex Parent'
  OBPlane/Geometry Component/GEOMETRY_EVAL_INIT() via 'Object Geometry UberEval'
  OBPlane/Transform Component/TRANSFORM_FINAL() via 'SoftBody Modifier'
  OBPlane/Transform Component/TRANSFORM_SIMULATION_INIT() via 'Simulation -> Final Transform'
  OBPlane/Transform Component/TRANSFORM_EVAL() via 'Transform Eval -> Simulation Init'
  OBPlane/Transform Component/TRANSFORM_PARENT() via 'Eval'
  OBPlane/Transform Component/TRANSFORM_LOCAL() via 'ObLocal -> ObParent'
  OBPlane/Transform Component/TRANSFORM_INIT() via 'Transform Init'
  OBCylinder/Geometry Component/GEOMETRY_EVAL() via 'Vertex Parent'
Detected 2 dependency cycles
ERROR (bke.modifier): C:\Users\blender\git\blender-v330\blender.git\source\blender\blenkernel\intern\modifier.c:456 BKE_modifier_set_error: Object: "Cylinder", Modifier: "MeshDeform", Cannot get mesh from cage object
ERROR (bke.modifier): C:\Users\blender\git\blender-v330\blender.git\source\blender\blenkernel\intern\modifier.c:456 BKE_modifier_set_error: Object: "Cylinder", Modifier: "MeshDeform.001", Cannot get mesh from cage object

Are you able to simplify the file so that it no longer has the dependency cycle and modifier errors, and still show an issue?

Thank you for the update @didactic. There are two dependency cycles reported in the console. Two Errors are also reported in the console involving both MeshDeform Modifiers. You can show the console by going `Window->Toggle System Console` You can also see this by starting Blender with `blender_debug_log.cmd` and reading the generated log. When rendering with Cycles, the dependency cycles and modifier errors are reported every frame. With EEVEE, the dependency cycles are reported 3 times, and the modifier error only once. When rendering, Cycles rebuilds it's dependency graph every frame (as far as I am aware), while EEVEE and Workbench (and the Cycle's viewport) are able to use parts of the dependency graph from the previous frame. Reading about the [Mesh Deform Modifier](https://docs.blender.org/manual/en/latest/modeling/modifiers/deform/mesh_deform.html), I am surprised to see that this is only an error in the Cycles rendered movie, as the cage mesh is intended to surround the mesh it is deforming, which it doesn't do in this file. ``` Dependency cycle detected: OBCylinder/Geometry Component/GEOMETRY_EVAL() depends on OBCube_B/Geometry Component/GEOMETRY_EVAL() via 'Mesh Deform Modifier' OBEmpty.B/Transform Component/TRANSFORM_FINAL() via 'Cast Modifier' OBEmpty.B/Transform Component/TRANSFORM_CONSTRAINTS() via 'ObConstraints -> Done' OBCube.B/Transform Component/TRANSFORM_FINAL() via 'Copy Location' OBCube.B/Transform Component/TRANSFORM_CONSTRAINTS() via 'ObConstraints -> Done' OBCube.003/Transform Component/TRANSFORM_FINAL() via 'Transformation' OBCube.003/Transform Component/TRANSFORM_SIMULATION_INIT() via 'Simulation -> Final Transform' OBCube.003/Transform Component/TRANSFORM_EVAL() via 'Transform Eval -> Simulation Init' OBCube.003/Transform Component/TRANSFORM_PARENT() via 'Eval' OBCube.003/Transform Component/TRANSFORM_LOCAL() via 'ObLocal -> ObParent' OBCube.003/Transform Component/TRANSFORM_INIT() via 'Transform Init' OBPlane.001/Geometry Component/GEOMETRY_EVAL() via 'Vertex Parent' OBPlane.001/Geometry Component/GEOMETRY_EVAL_INIT() via 'Object Geometry UberEval' OBPlane.001/Transform Component/TRANSFORM_FINAL() via 'SoftBody Modifier' OBPlane.001/Transform Component/TRANSFORM_SIMULATION_INIT() via 'Simulation -> Final Transform' OBPlane.001/Transform Component/TRANSFORM_EVAL() via 'Transform Eval -> Simulation Init' OBPlane.001/Transform Component/TRANSFORM_PARENT() via 'Eval' OBPlane.001/Transform Component/TRANSFORM_LOCAL() via 'ObLocal -> ObParent' OBPlane.001/Transform Component/TRANSFORM_INIT() via 'Transform Init' OBCylinder/Geometry Component/GEOMETRY_EVAL() via 'Vertex Parent' Dependency cycle detected: OBCylinder/Geometry Component/GEOMETRY_EVAL() depends on OBCube_A/Geometry Component/GEOMETRY_EVAL() via 'Mesh Deform Modifier' OBEmpty.A/Transform Component/TRANSFORM_FINAL() via 'Cast Modifier' OBEmpty.A/Transform Component/TRANSFORM_CONSTRAINTS() via 'ObConstraints -> Done' OBCube.A/Transform Component/TRANSFORM_FINAL() via 'Copy Location' OBCube.A/Transform Component/TRANSFORM_CONSTRAINTS() via 'ObConstraints -> Done' OBCube.004/Transform Component/TRANSFORM_FINAL() via 'Transformation' OBCube.004/Transform Component/TRANSFORM_SIMULATION_INIT() via 'Simulation -> Final Transform' OBCube.004/Transform Component/TRANSFORM_EVAL() via 'Transform Eval -> Simulation Init' OBCube.004/Transform Component/TRANSFORM_PARENT() via 'Eval' OBCube.004/Transform Component/TRANSFORM_LOCAL() via 'ObLocal -> ObParent' OBCube.004/Transform Component/TRANSFORM_INIT() via 'Transform Init' OBPlane/Geometry Component/GEOMETRY_EVAL() via 'Vertex Parent' OBPlane/Geometry Component/GEOMETRY_EVAL_INIT() via 'Object Geometry UberEval' OBPlane/Transform Component/TRANSFORM_FINAL() via 'SoftBody Modifier' OBPlane/Transform Component/TRANSFORM_SIMULATION_INIT() via 'Simulation -> Final Transform' OBPlane/Transform Component/TRANSFORM_EVAL() via 'Transform Eval -> Simulation Init' OBPlane/Transform Component/TRANSFORM_PARENT() via 'Eval' OBPlane/Transform Component/TRANSFORM_LOCAL() via 'ObLocal -> ObParent' OBPlane/Transform Component/TRANSFORM_INIT() via 'Transform Init' OBCylinder/Geometry Component/GEOMETRY_EVAL() via 'Vertex Parent' Detected 2 dependency cycles ERROR (bke.modifier): C:\Users\blender\git\blender-v330\blender.git\source\blender\blenkernel\intern\modifier.c:456 BKE_modifier_set_error: Object: "Cylinder", Modifier: "MeshDeform", Cannot get mesh from cage object ERROR (bke.modifier): C:\Users\blender\git\blender-v330\blender.git\source\blender\blenkernel\intern\modifier.c:456 BKE_modifier_set_error: Object: "Cylinder", Modifier: "MeshDeform.001", Cannot get mesh from cage object ``` Are you able to simplify the file so that it no longer has the dependency cycle and modifier errors, and still show an issue?

Ward Darcey commented

2022-09-20 01:32:43 +02:00

Thank you for checking this out. You are right - there is a dependency error & I think I have just found is the source.
In summary:-
The small bouncing triangles, ie responding to their "physics", are parented to 3 vertices on the same mesh,
& within the area of influence, that the Mesh Deform Modifier is animating!

So, there is a "circular reference" happening - this is a design error on my part. Strange that this has never come up before, probably because the
bouncing triangle (physics object) has always been parented elsewhere. When I change the parenting to a related bone or somethhing else,
I get full cycles render out with no problems, ie that issue disappears entirely!
Thanks again!

So - the stuff you didn't know you didn't know! - really appreciate you looking at this, it had me perplexed!

Thank you for checking this out. You are right - there is a dependency error & I think I have just found is the source. In summary:- The small bouncing triangles, ie responding to their "physics", are parented to 3 vertices on the same mesh, & within the area of influence, that the Mesh Deform Modifier is animating! So, there is a "circular reference" happening - this is a design error on my part. Strange that this has never come up before, probably because the bouncing triangle (physics object) has always been parented elsewhere. When I change the parenting to a related bone or somethhing else, I get full cycles render out with no problems, ie that issue disappears entirely! Thanks again! So - the stuff you didn't know you didn't know! - really appreciate you looking at this, it had me perplexed!

Evan Wilson commented

2022-09-20 03:30:28 +02:00

Changed status from 'Needs User Info' to: 'Archived'

Evan Wilson closed this issue

2022-09-20 03:30:28 +02:00

Evan Wilson commented

2022-09-20 03:30:28 +02:00

Glad to see that you were able to solve the issue. I’ll go ahead and archive this report.

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Animated Mesh renders correctly in Eevee, Workbench, but not Cycles #101051