Maniphest T80739

Particle Created at Object's Origin Even If No Face Is There
Needs Information from Developers, Normal
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Authored By
Jonathan Manton (jmanton)
Sep 13 2020, 6:55 AM
Tags
  • BF Blender
Subscribers
Ankit Meel (ankitm)
Daegon Kim (dk123)
Germano Cavalcante (mano-wii)
Ivan Arsic (arsa3d)
Jeric Chard (jeric_synergy)
Jonathan Manton (jmanton)
Mike Drake (LichenDigital)
1 More Subscribers

Description

System Information
Operating system: Both Windows and Linux
Graphics card: Various nVidia cards

Blender Version
Broken: 2.90
Worked: (newest version of Blender that worked as expected)

Create an object with two separate components. Set its origin to somewhere strictly between the two components, so that the origin is not part of any face. Generate particles on that object. Then a particle can appear at the origin.

Exact steps for others to reproduce the error
Create two planes. Space them apart. Join them. Set the joined object's origin to geometry. Put a particle system on it. Change end time to 1. Observe a particle is generated at the object's origin even though there is no face there.

Particle Bug.blend773 KBDownload

system-info.txt21 KBDownload

Related Objects

Mentioned Here
rB6e7617211b67: UI messages fixes...
T80537: Particle source face creates an unwanted object in the middle of mesh

Event Timeline

Jonathan Manton (jmanton) created this task.Sep 13 2020, 6:55 AM
Germano Cavalcante (mano-wii) added a subscriber: Germano Cavalcante (mano-wii).Sep 15 2020, 7:12 PM

I cannot reproduce the problem from scratch.
It only appears in the attached file.

Has it been fixed in the daily build?
https://builder.blender.org/download/

Jonathan Manton (jmanton) added a comment.Sep 16 2020, 2:07 AM

I installed the latest build: blender-2.91.0-6624c4c22514-linux64
The following steps will recreate the problem.

  1. Delete cube.
  2. Add a plane.
  3. Go to edit mode.
  4. Add a plane.
  5. Grab it and move it away from the first plane (no overlap).
  6. Go back to object mode.
  7. Object > Set Origin > Origin to Geometry
  8. Confirm the origin is not touching either plane.
  9. Add a particle system and modify its End time to 1 (down from 200).
  10. Confirm there is a particle (white halo) at the origin of the plane. In greater detail, there are lots of particles covering both planes, but there is a lone particle halfway between the two planes that should not be there.
Richard Antalik (ISS) added a subscriber: Richard Antalik (ISS).Sep 16 2020, 3:31 PM

I can't reproduce this from scratch.

In provided file if I go to edit mode and back, or touch any setting of particle system the particle at origin dissappears.

There was similar report recently though so there is probably something to it, but I can't find it anymore

Richard Antalik (ISS) added a comment.Sep 16 2020, 3:33 PM

Found it: T80537

Jonathan Manton (jmanton) added a comment.Sep 16 2020, 4:12 PM

In case you missed it, please see my comment above where I show how to recreate the problem from scratch. The comment starts with "I installed the latest build: blender-2.91.0-6624c4c22514-linux64. The following steps will recreate the problem.".

(Note too that this first occurred in an actual project: there was a very noticeable bright object in the middle of the rendered animation when there shouldn't have been. So presumably if you extend the above step-by-step instructions to render particles as objects then render the animation, you will see an unwanted particle/object in the rendered animation.)

Richard Antalik (ISS) added a comment.Sep 17 2020, 1:46 PM
In T80739#1017057, @Jonathan Manton (jmanton) wrote:

In case you missed it, please see my comment above where I show how to recreate the problem from scratch

Thanks, I din not miss that. I followed that procedure as well.

Germano Cavalcante (mano-wii) changed the task status from Needs Triage to Needs Information from User.Sep 18 2020, 8:57 PM

I also can't reproduce form scratch.
Unfortunately unless there are clear instructions on how to reproduce it from scratch we cannot debug this any further.
GIF:

Jonathan Manton (jmanton) added a comment.EditedSep 19 2020, 3:56 AM

I watched the GIF and the steps are correct. My first suggestion is to try increasing the number of particles generated and also changing the seed. I don't know what influences the random generation of particles, so to be on the conservative side, the following steps now include precise distances and seed values. Although I haven't tested the following steps on different setups, in the past I have found the problem to be easy to reproduce on two different blender versions and two different computers, one Windows and one Linux.

I am using the standard Blender 2.90 for this.

system-info.txt21 KBDownload

[ I used the daily build of Blender last time. ]

  1. Select "General" on splash screen.
  2. Delete cube.
  3. Press shift-A M P to add a plane.
  4. Press shift-D X 4 to duplicate then place 4 units away on the X axis.
  5. Select both planes then type Ctrl J to join.
  6. Object > Set Origin > Origin to Geometry
  7. Particle Properties > "+" to create a particle system.
  8. Change End to 1 (down from 200).
  9. I already get a particle at the origin of the planes:
  1. Changing seed to any value between 1 and 20 seems to alter the distribution (as it should) but keep the particle at the origin.
  1. Set the Seed to 555.
  2. Set the Number to 51. There is no particle at the origin:
  3. Set the Number to 52. A particle appears at the origin:
  1. Place the 3D cursor anywhere on the screen.
  2. Object > Set Origin > Origin to 3D Cursor
  3. The particle follows it, still appearing at the origin:

This is a mystery, as it seems very robust to recreate.

ps. Here is the Blend file at the end of the last step.

Particle At Origin Bug.blend747 KBDownload

Jonathan Manton (jmanton) added a comment.EditedSep 19 2020, 4:26 AM

A faster way to recreate the problem is to use the "Particle At Origin Bug.blend" file attached to the previous comment.

  1. Download and run, say, blender-2.91.0-6624c4c22514-linux64
  2. Open Particle At Origin Bug.blend
  3. In particle system settings, change Emission > Number to 51 (down from 52). Observe the particle at the origin disappears (where the 3D cursor is).
  4. Change Emission > Number back to 52. Observe the particle at the origin appears again (where the 3D cursor is).

If this does not work, then somehow there is a dependence on the hardware/OS/compiler....

ps. The above recreated the bug with blender-2.91.0-6624c4c22514-linux64 and I have now also confirmed it recreates the bug with Windows 2.90:

system-info.txt22 KBDownload

Richard Antalik (ISS) added a subscriber: Philipp Oeser (lichtwerk).Sep 28 2020, 7:29 AM

Can't recreate this issue even with steps provided.

I don't have access to nvidia card, so I can't check that. @Philipp Oeser (lichtwerk) can you check?

Philipp Oeser (lichtwerk) added a comment.Sep 28 2020, 10:44 AM

Opening Particle At Origin Bug.blend I can see the particle at the origin, however changing settings (eg. Emission > Number to 51 and back to 52) will make it disappear and never come back.
Also not able to reproduce this from scratch.

Ankit Meel (ankitm) added a subscriber: Ankit Meel (ankitm).EditedOct 7 2020, 1:04 PM

Cannot redo on Intel HD 6000, macOS 10.14, Blender version rB6e7617211b67: UI messages fixes....
No particle at the origin by following the steps.

Ankit Meel (ankitm) changed the task status from Needs Information from User to Needs Information from Developers.Oct 7 2020, 1:04 PM
Ankit Meel (ankitm) merged a task: T80537: Particle source face creates an unwanted object in the middle of mesh.
Ankit Meel (ankitm) added a subscriber: Daegon Kim (dk123).
Jeric Chard (jeric_synergy) added a subscriber: Jeric Chard (jeric_synergy).Aug 9 2021, 12:32 AM

FWIW, I'm experiencing the same bug, 08/008/21, on v2.93, ie "particles being emitted inappropriately from emitter's origin". In this case it is complicated with the object being a Boolean intersection object, and so only "being there" some of the time. Blend file attached.

Bad_Particles.blend1 MBDownload

Mike Drake (LichenDigital) added a subscriber: Mike Drake (LichenDigital).Jan 6 2022, 10:37 PM
In T80739#1203496, @Jeric Chard (jeric_synergy) wrote:

FWIW, I'm experiencing the same bug, 08/008/21, on v2.93, ie "particles being emitted inappropriately from emitter's origin". In this case it is complicated with the object being a Boolean intersection object, and so only "being there" some of the time. Blend file attached.

Bad_Particles.blend1 MBDownload

Hey Jeric! I had a similar issue where particles were being emitted from the origin on an object that had a boolean on it. Checking the "Use Modifier Stack" option in the particle Source options fixed it for me. Can you give that a try?

Ivan Arsic (arsa3d) added a subscriber: Ivan Arsic (arsa3d).Jul 13 2022, 7:59 PM

same here, its definetely a bug.

I was using mask modifier to remove geo so i can control emission of particles. so when theres no geo at all (all masked out) it just starts emiting from origin.

quick workaround is to move origin somewhere away from camera so you cannot see those unwanted particles anymore