Modulo node making unexpected/inconsistent behaviour #67623

New Issue

Nicolas · 2019-07-24T23:29:23+02:00

Nicolas commented

2019-07-24 23:29:23 +02:00

System Information
Operating system: Windows 10
Graphics card: Nvidia GeForce GTX 1060 Version 419.35

Blender Version
Broken: 2.80 Release Candidate 2 (downloaded today, no more information on the splash screen)

Short description of error
In the shader editor, the modulo operations returns sometimes a negative number after taking zero as parameter (each vertex of the wall has a Y coordinate of 0). This seems to happen on random pixels : sometimes the number returned by the modulo seems to be equal to 0, and sometimes to -1. The result depends on the point of view.

Screenshot with this modulo operator :

Screenshot without the modulo : here the behaviour is normal so the problem comes from the modulo.

I think that the modulo should always return the same value on the entire wall since it has one single Y coordinate (return 0 if I am right).

Exact steps for others to reproduce the error
Go into render mode. Move the viewpoint and test values on the "greater than" node.
Blender file :
bug.blend

**System Information** Operating system: Windows 10 Graphics card: Nvidia GeForce GTX 1060 Version 419.35 **Blender Version** Broken: 2.80 Release Candidate 2 (downloaded today, no more information on the splash screen) **Short description of error** In the shader editor, the modulo operations returns sometimes a negative number after taking zero as parameter (each vertex of the wall has a Y coordinate of 0). This seems to happen on random pixels : sometimes the number returned by the modulo seems to be equal to 0, and sometimes to -1. The result depends on the point of view. Screenshot with this modulo operator : ![withModulo.JPG](https://archive.blender.org/developer/F7627122/withModulo.JPG) Screenshot without the modulo : here the behaviour is normal so the problem comes from the modulo. ![withoutModulo.JPG](https://archive.blender.org/developer/F7627124/withoutModulo.JPG) I think that the modulo should always return the same value on the entire wall since it has one single Y coordinate (return 0 if I am right). **Exact steps for others to reproduce the error** Go into render mode. Move the viewpoint and test values on the "greater than" node. Blender file : [bug.blend](https://archive.blender.org/developer/F7627150/bug.blend)

Nicolas commented

2019-07-24 23:29:23 +02:00

Added subscriber: @Acrolyph

Lance Phan commented

2019-07-25 07:12:38 +02:00

Added subscriber: @ssendam

Lance Phan commented

2019-07-25 07:12:38 +02:00

It seem too be a problem with precision. The vertices are perfectly on the yz plane but the faces are slightly incorrect, some parts are above while some other parts are below the yz plane which result in a weird render. If you move the vertices 0.001 unit along the y axis, it will solve the problem.
And it seem to happen only to Eevee

It seem too be a problem with precision. The vertices are perfectly on the yz plane but the faces are slightly incorrect, some parts are above while some other parts are below the yz plane which result in a weird render. If you move the vertices 0.001 unit along the y axis, it will solve the problem. And it seem to happen only to Eevee

Sebastian Parborg commented

2019-08-05 14:20:02 +02:00

Added subscribers: @fclem, @ZedDB

Clément Foucault was assigned by Sebastian Parborg

2019-08-05 14:20:02 +02:00

Sebastian Parborg commented

2019-08-05 14:20:02 +02:00

@fclem is this a bug or a limitation with eevee?

blender-admin commented

2019-08-07 13:08:28 +02:00

This issue was referenced by 3e27dd5b55

This issue was referenced by 3e27dd5b553e83c9d6358f5a93597c86a2bf3cb1

Clément Foucault commented

2019-08-07 13:09:36 +02:00

Changed status from 'Open' to: 'Resolved'

Clément Foucault closed this issue

2019-08-07 13:09:36 +02:00

Roel Koster commented

2019-08-07 15:35:42 +02:00

Added subscriber: @kostex

Roel Koster commented

2019-08-07 15:35:42 +02:00

Hey Clement,

Just compiled including this commit on OSX, but rendering a scene makes building BVH extremely slow??
One commit earlier and things are fine.
On Linux (Ubuntu 18.04LTS) your commit does not show slowdown.. any ideas?

Thanks,
Roel

Hey Clement, Just compiled including this commit on OSX, but rendering a scene makes building BVH extremely slow?? One commit earlier and things are fine. On Linux (Ubuntu 18.04LTS) your commit does not show slowdown.. any ideas? Thanks, Roel

Clément Foucault commented

2019-08-07 17:01:01 +02:00

This has nothing to do with the BVH. It does not even touch cycles code.

Roel Koster commented

2019-08-07 17:43:19 +02:00

That what's made me type a lot of question marks..
Maybe you could think of (another) reason why this happens..
It's just the difference in this commit with the previous one that slow things down..

but we'll see if there are more or new tasks arise in the coming days stating the same.
Thanks,
Roel

That what's made me type a lot of question marks.. Maybe you could think of (another) reason why this happens.. It's just the difference in this commit with the previous one that slow things down.. but we'll see if there are more or new tasks arise in the coming days stating the same. Thanks, Roel

Clément Foucault commented

2019-08-07 17:48:46 +02:00

@kostex I would suggest to double check by reverting only my commit to see if that comes from it. But I highly doubt.

Roel Koster commented

2019-08-07 18:01:31 +02:00

I did just that before I commented at all..

I've did some further investigation, and it seems that the scene I was testing it on had Subdivision Surface with adaptive sampling on.
When I disable adaptive, the scene renders like normal speed.
Does this ring any bell maybe in combination with this commit?

Again, only on osx

I did just that before I commented at all.. I've did some further investigation, and it seems that the scene I was testing it on had Subdivision Surface with adaptive sampling on. When I disable adaptive, the scene renders like normal speed. Does this ring any bell maybe in combination with this commit? Again, only on osx

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Modulo node making unexpected/inconsistent behaviour #67623