Bullet Physic Rigid Body Updates In Viewport Playback, Object Using Constraints (Loc,Rot) Breaks One Frame In To Animation When Rendering, But Viewport Playback Updates Correctly #42294

New Issue

Martin Lindelöf · 2014-10-19T13:18:55+02:00

Martin Lindelöf commented

2014-10-19 13:18:55 +02:00

System Information
Operating system and graphics card

Win 8.1, nv gfx 580

Blender Version
Broken: 2.72a 2014-10-18 15:49 c35a649 // buildbot
Worked: 2.71 http://instagram.com/p/ukfI2PI7_K/ <--- video comparisson.

Short description of error
Summary:
Viewport playback of a rigid body simulation with an object using copy loc & rot constraints works, rendering doesn't.

Long desc:
Using A Bullet Physics Object for placeholder during Rigid Body Simulation, Render Object has two constraints copy location and copy rotation to update according to the bphysics rigid object.
I've done this because the Render Object in question has Armature. First I tried parenting to the Rigid Body, but since it's just a placeholder and I want it to be invisible for rendering, it's children becomes invisible.
That's when I came up with the idea to have them totally seperate and just copy loc/rot from the Rigid Body. And it works pretty well when baked, in viewport no visual errors. When rendering it only works the very first frame,
2nd frame into animation, the render object is gone. I have no idea where, since viewport playback works.

I investigated it a bit more, 2.71 works perfect, but 2.72a & 2.72b I get all kinda weird behavious on just simple scenes with rigid body physics, in one case (the video http://instagram.com/p/ukfI2PI7_K/) they're just invisible.
anything connected to them via constraints or parenting dissapears also during rendering. Viewport playback works great.

Exact steps for others to reproduce the error
Based on a (as simple as possible) attached .blend file with minimum amount of steps
I can attach the file, minimal steps is just playback in viewport [ALT+A] and check that it's working, then try render on frame 1, and 2 and see the difference for me frame1 it's visible, frame2 it's gone. Talking about the small cube (render object) with a cute face.untitled.blend

**System Information** Operating system and graphics card Win 8.1, nv gfx 580 **Blender Version** Broken: 2.72a 2014-10-18 15:49 c35a649 // buildbot Worked: 2.71 http://instagram.com/p/ukfI2PI7_K/ <--- video comparisson. **Short description of error** **Summary:** Viewport playback of a rigid body simulation with an object using copy loc & rot constraints works, rendering doesn't. **Long desc:** Using A Bullet Physics Object for placeholder during Rigid Body Simulation, Render Object has two constraints copy location and copy rotation to update according to the bphysics rigid object. I've done this because the Render Object in question has Armature. First I tried parenting to the Rigid Body, but since it's just a placeholder and I want it to be invisible for rendering, it's children becomes invisible. That's when I came up with the idea to have them totally seperate and just copy loc/rot from the Rigid Body. And it works pretty well when baked, in viewport no visual errors. When rendering it only works the very first frame, 2nd frame into animation, the render object is gone. I have no idea where, since viewport playback works. I investigated it a bit more, 2.71 works perfect, but 2.72a & 2.72b I get all kinda weird behavious on just simple scenes with rigid body physics, in one case (the video http://instagram.com/p/ukfI2PI7_K/) they're just invisible. anything connected to them via constraints or parenting dissapears also during rendering. Viewport playback works great. **Exact steps for others to reproduce the error** *Based on a (as simple as possible) attached .blend file with minimum amount of steps* I can attach the file, minimal steps is just playback in viewport [ALT+A] and check that it's working, then try render on frame 1, and 2 and see the difference for me frame1 it's visible, frame2 it's gone. Talking about the small cube (render object) with a cute face.[untitled.blend](https://archive.blender.org/developer/F118320/untitled.blend)

Martin Lindelöf commented

2014-10-19 13:18:55 +02:00

Changed status to: 'Open'

Martin Lindelöf commented

2014-10-19 13:18:55 +02:00

Added subscriber: @MartinLindelof

Joshua Leung commented

2014-10-20 02:13:44 +02:00

Added subscriber: @JoshuaLeung

Joshua Leung commented

2014-10-20 02:24:49 +02:00

Changed status from 'Open' to: 'Archived'

Joshua Leung closed this issue

2014-10-20 02:24:49 +02:00

Joshua Leung self-assigned this 2014-10-20 02:24:49 +02:00

Joshua Leung commented

2014-10-20 02:24:49 +02:00

IIRC, this is a consequence of limitations on the way that things are evaluated in Blender currently. The rigidbody sim can only happen once all objects (and thus, their constraints) have been evaluated, as it needs to take into account where collision objects have moved to.

So, known limitation that cannot be fixed in current Blender :(

IIRC, this is a consequence of limitations on the way that things are evaluated in Blender currently. The rigidbody sim can only happen once all objects (and thus, their constraints) have been evaluated, as it needs to take into account where collision objects have moved to. So, known limitation that cannot be fixed in current Blender :(

Martin Lindelöf commented

2014-10-20 10:06:42 +02:00

Oh that's weird, because the viewport playback goes well, the rigid body does the simulation and the object with constraint updates well. Until it's rendering, I remember now that I am running on GPU will check if it's working on CPU. If it could be something that gets disconnected when building BVH and sent over to GPU. I will investigate and try to find a work around. I want to have 200 or 300 of these objects later on and let the bullet physics do the simulation and bake it.

Martin Lindelöf commented

2014-10-21 14:02:47 +02:00

I think it was closed to early, because testing at work on Mac and CPU render, it's not a problem to have placeholder bullet physics object, then have objects with constraints to copy Loc&Rot from the simulated physics objects. And it works flawless. I am thinking when using GPU rendering in Cycles it might be a bug, that objects which properties are used in constraints aren't being calculated first or something. test_instablast0001-0050.mov

Im attaching a viewport render, (which worked great in my .blend file), but also a CPU/CYCLES rendered animation which where the constraints works. test0001-0050.mov

I think it was closed to early, because testing at work on Mac and CPU render, it's not a problem to have placeholder bullet physics object, then have objects with constraints to copy Loc&Rot from the simulated physics objects. And it works flawless. I am thinking when using GPU rendering in Cycles it might be a bug, that objects which properties are used in constraints aren't being calculated first or something. [test_instablast0001-0050.mov](https://archive.blender.org/developer/F118834/test_instablast0001-0050.mov) Im attaching a viewport render, (which worked great in my .blend file), but also a CPU/CYCLES rendered animation which where the constraints works. [test0001-0050.mov](https://archive.blender.org/developer/F118835/test0001-0050.mov)

Martin Lindelöf commented

2014-10-25 11:37:50 +02:00

Joshua, I had older projects with bullet physics, rigid bodies. from 2.71, I tried a simple scene with boxes falling, it's working great on GPU/CYCLES in 2.71, not so great in latest buildbot 2.72(b?). check out the video.
http://instagram.com/p/ukfI2PI7_K/

if it is so, that there's been changes to evaluations in current 2.72 versions that brake this, I think it's important to fix it. since it works in viewport etcetera rendering is just broken. doesn't look good for new users. For me I can work around, use 2.72 to make my scenes and render with 2.71.

can you change status to "investigate" from "archived" I think this bug, or broken feature needs to be looked into more.

Joshua, I had older projects with bullet physics, rigid bodies. from 2.71, I tried a simple scene with boxes falling, it's working great on GPU/CYCLES in 2.71, not so great in latest buildbot 2.72(b?). check out the video. http://instagram.com/p/ukfI2PI7_K/ if it is so, that there's been changes to evaluations in current 2.72 versions that brake this, I think it's important to fix it. since it works in viewport etcetera rendering is just broken. doesn't look good for new users. For me I can work around, use 2.72 to make my scenes and render with 2.71. can you change status to "investigate" from "archived" I think this bug, or broken feature needs to be looked into more.

Joshua Leung commented

2014-10-25 12:05:29 +02:00

Changed status from 'Archived' to: 'Open'

Joshua Leung reopened this issue

2014-10-25 12:05:29 +02:00

Joshua Leung commented

2014-10-25 12:05:29 +02:00

Hmm... looks like this may not have been what I thought it was. Reopening :)

Joshua Leung removed their assignment 2014-10-25 12:05:43 +02:00

Martin Lindelöf commented

2014-10-28 11:21:35 +01:00

did some work on my scene during bconf, I played around with motion blur setting (default 0.5) to 1.0, and 2.0 it didn't seem to have any effect on the Rigid Bodies rendering or not. But sometimes when selecting a object that is not a RB or anything but has animation, and rendering it sometimes worked. really really weird. by working I mean F12 rendering a frame.

Shift+Z to render viewport, always works, as stated before, viewport update for the RB simulation always worked. So my hunch it is something to do when sending to GPU, BVH Building?

the BVH building is way to fast in blender to even see it :D in simpler scenes, but I dunno if viewport rendering builds a BVH or not, F12 render frame does it. It's just speculations, and I have no insight or idea about Cycles code but maybe BVH had have some updates recently?

did some work on my scene during bconf, I played around with motion blur setting (default 0.5) to 1.0, and 2.0 it didn't seem to have any effect on the Rigid Bodies rendering or not. But sometimes when selecting a object that is not a RB or anything but has animation, and rendering it sometimes worked. really really weird. by working I mean F12 rendering a frame. Shift+Z to render viewport, always works, as stated before, viewport update for the RB simulation always worked. So my hunch it is something to do when sending to GPU, BVH Building? the BVH building is way to fast in blender to even see it :D in simpler scenes, but I dunno if viewport rendering builds a BVH or not, F12 render frame does it. It's just speculations, and I have no insight or idea about Cycles code but maybe BVH had have some updates recently?

blender-admin commented

2014-10-29 15:01:19 +01:00

This issue was referenced by f7dedbc3ce

This issue was referenced by f7dedbc3ce101d80366540f73842f90091a88a1e

Lukas Tönne commented

2014-10-29 15:01:58 +01:00

Changed status from 'Open' to: 'Resolved'

Lukas Tönne closed this issue

2014-10-29 15:01:58 +01:00

Lukas Tönne commented

2014-10-29 15:01:58 +01:00

Closed by commit f7dedbc3ce.

Closed by commit f7dedbc3ce.

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Bullet Physic Rigid Body Updates In Viewport Playback, Object Using Constraints (Loc,Rot) Breaks One Frame In To Animation When Rendering, But Viewport Playback Updates Correctly #42294