Particle Random distribution changed between 2.74 and newer versions #46484

New Issue

Antonio Buch · 2015-10-14T17:56:48+02:00

Antonio Buch commented

2015-10-14 17:56:48 +02:00

System Information
Windows 8.1
GeForce GTX TITAN Black
(Tested in other computer too)

Blender Version
Broken: 2.76 44f7dd6 (or 2.75)

Short description of error
When you open a 2.74 file in a newer version (2.75 or 2.76) the random distribution of the particles on a system change. So if you re-render an older project to add another view (I mean stereoscopic, as my case) the new render will have the particles in another position.

Steps for others to reproduce the error
Open and compare the attached file in 2.74 and newer versions or follow the steps to recreate the bug.

Particle_bug.blend

Open a new file with 2.74
Add a Particle System to the default cube
Set the number of particles low (5-10 particles), set the end of emission at 1.00. At Physics select No
Save the .blend file
Open the file in a newer Blender version and compare the distribution of the particles (Easier from camera view with wireframe display)

**System Information** Windows 8.1 GeForce GTX TITAN Black (Tested in other computer too) **Blender Version** Broken: 2.76 44f7dd6 (or 2.75) **Short description of error** When you open a 2.74 file in a newer version (2.75 or 2.76) the random distribution of the particles on a system change. So if you re-render an older project to add another view (I mean stereoscopic, as my case) the new render will have the particles in another position. **Steps for others to reproduce the error** Open and compare the attached file in 2.74 and newer versions or follow the steps to recreate the bug. [Particle_bug.blend](https://archive.blender.org/developer/F244954/Particle_bug.blend) * Open a new file with 2.74 * Add a Particle System to the default cube * Set the number of particles low (5-10 particles), set the end of emission at 1.00. At Physics select No * Save the .blend file * Open the file in a newer Blender version and compare the distribution of the particles (Easier from camera view with wireframe display)

Antonio Buch commented

2015-10-14 17:56:48 +02:00

Changed status to: 'Open'

Antonio Buch commented

2015-10-14 17:56:48 +02:00

Added subscriber: @antoniobuch1

Bastien Montagne commented

2015-10-14 19:22:10 +02:00

Added subscribers: @LukasTonne, @Sergey, @mont29

Bastien Montagne commented

2015-10-14 19:22:11 +02:00

AFAIK this is known and expected - we have issues with our random generator and threaded processes, and went through several steps and hacks (and even now not sure situation is totally under control)… @Sergey or @LukasTonne should know more about this?

Antonio Buch commented

2015-10-14 19:36:12 +02:00

Known and expected... I hope we can find a solution. I have to render about 2500 frames that takes 20 minutes each for one eye and I already have the other eye rendered. Don't wont to render both views. And is for a commercial project, with deadlines.

If there's no fix to this, is there any build with Multiview but without this issue?

Known and expected... I hope we can find a solution. I have to render about 2500 frames that takes 20 minutes each for one eye and I already have the other eye rendered. Don't wont to render both views. And is for a commercial project, with deadlines. If there's no fix to this, is there any build with Multiview but without this issue?

Bastien Montagne commented

2015-10-14 19:56:15 +02:00

Patching 2.74 codebase with multiview would be rather hard imho (though probably possible using git history), but as of finding some multiview build based on 2.74…

What you should be able to do, though, is rendering the other 'eye' in 2.74 (by adding yourself a second camera and all), and then use 2.76 to import both views and composite them?

Patching 2.74 codebase with multiview would be rather hard imho (though probably possible using git history), but as of finding some multiview build based on 2.74… What you should be able to do, though, is rendering the other 'eye' in 2.74 (by adding yourself a second camera and all), and then use 2.76 to import both views and composite them?

Antonio Buch commented

2015-10-14 20:01:48 +02:00

That solution might be the only one... But the 3D camera has the Convergence Plane and the Interocular Distance animated through the hole scene. Replicating this with a second camera is tough but not impossible I think.

Brecht Van Lommel commented

2015-10-14 21:02:04 +02:00

Added subscriber: @brecht

Brecht Van Lommel commented

2015-10-14 21:02:04 +02:00

It was probably this commit that changed the distribution: 86f80c481c.

If you can make your own build, removing that one line of code will probably give you the same distribution as 2.74, though I'm not 100% sure since there might have been other changes that affect your scene.

It was probably this commit that changed the distribution: 86f80c481c. If you can make your own build, removing that one line of code will probably give you the same distribution as 2.74, though I'm not 100% sure since there might have been other changes that affect your scene.

Brecht Van Lommel commented

2015-10-14 21:20:49 +02:00

To be clear, we should not revert that commit. It changes the distribution back to what it was in 2.73, since the one in 2.74 was quite broken and generating overlapping particles / hairs.

Sergey Sharybin commented

2016-01-26 16:01:08 +01:00

Changed status from 'Open' to: 'Archived'

Sergey Sharybin closed this issue

2016-01-26 16:01:08 +01:00

Sergey Sharybin self-assigned this 2016-01-26 16:01:08 +01:00

Sergey Sharybin commented

2016-01-26 16:01:08 +01:00

There were indeed some unavoidable changes in patterns which we needed to do in order to solve some other issues. Not much we can do for this one here actually.

Thanks for the report, but it was just relying on some broken logic of particles.. Closing now.

There were indeed some unavoidable changes in patterns which we needed to do in order to solve some other issues. Not much we can do for this one here actually. Thanks for the report, but it was just relying on some broken logic of particles.. Closing now.

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Particle Random distribution changed between 2.74 and newer versions #46484