Triangulation Modifier breaks split normals #51117

New Issue

notallowed · 2017-04-03T14:54:41+02:00

notallowed commented

2017-04-03 14:54:41 +02:00

System Information
Linux Mint 17.3
Intel i7 4770
Nvidia GTX 760

Blender Version
Broken: 2.78c.e92f2352830

Short description of error
Normals become broken, when using mesh with edited split normals and then adding triangulation modifier on the top of it.

PS: I have tried even on daily build, same problem: blender-2.78-54a60eff24
PS2: I tried to search for this problem in developer system, but did find one, that's why I am opening new issue.

Exact steps for others to reproduce the error

Create cube, bevel all edges
Create split normals -> edit normals somehow. I used weighted normals calculation -> https://blenderartists.org/forum/showthread.php?372785-Addon-Weighted-Normals-Calculator
Add triangulation modifier
Normals gets distorted! :(

**System Information** Linux Mint 17.3 Intel i7 4770 Nvidia GTX 760 **Blender Version** Broken: 2.78c.e92f2352830 **Short description of error** Normals become broken, when using mesh with edited split normals and then adding triangulation modifier on the top of it. PS: I have tried even on daily build, same problem: blender-2.78-54a60eff24 PS2: I tried to search for this problem in developer system, but did find one, that's why I am opening new issue. **Exact steps for others to reproduce the error** 1. Create cube, bevel all edges 2. Create split normals -> edit normals somehow. I used weighted normals calculation -> https://blenderartists.org/forum/showthread.php?372785-Addon-Weighted-Normals-Calculator 3. Add triangulation modifier 4. Normals gets distorted! :(

notallowed commented

2017-04-03 14:54:41 +02:00

Changed status to: 'Open'

notallowed commented

2017-04-03 14:54:41 +02:00

Added subscriber: @simon_lusenc

Germano Cavalcante commented

2017-04-05 16:00:49 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2017-04-05 16:00:49 +02:00

Hi @simon_lusenc,

Could you simplify the code to reproduce the bug?
To understand the bug, it is necessary to analyze the attached code, and this is not practical for developers who already have to analyze a stack of 323 bugs at the moment :\

Hi @simon_lusenc, Could you simplify the code to reproduce the bug? To understand the bug, it is necessary to analyze the attached code, and this is not practical for developers who already have to analyze a stack of 323 bugs at the moment :\

notallowed commented

2017-04-06 10:12:46 +02:00

Well actually you don't even need to check the add-on, because it's not related to add-on. Add-on just calculates normals and assign them back to mesh. The real problem is that once you have that mesh and you apply triangulation on it, normals get distorted.

I have created simple blend file for you, with 2 objects: broken_normals.blend

original -> is beveled cube with custom split normals
broken -> is shallow duplicate (it uses same mesh as original) and has triangulation modifier which brakes normals
To check it just go into the edit mode of each object and you will see the difference.

And sorry for not attaching blend file before ;)

Well actually you don't even need to check the add-on, because it's not related to add-on. Add-on just calculates normals and assign them back to mesh. The real problem is that once you have that mesh and you apply triangulation on it, normals get distorted. I have created simple blend file for you, with 2 objects: [broken_normals.blend](https://archive.blender.org/developer/F537130/broken_normals.blend) 1. original -> is beveled cube with custom split normals 2. broken -> is shallow duplicate (it uses same mesh as original) and has triangulation modifier which brakes normals To check it just go into the edit mode of each object and you will see the difference. And sorry for not attaching blend file before ;)

Dalai Felinto commented

2017-04-06 18:59:53 +02:00

Added subscribers: @ideasman42, @dfelinto

Dalai Felinto commented

2017-04-06 18:59:53 +02:00

@ideasman42 This is the expected behaviour as far as I can see, no?

Germano Cavalcante commented

2017-04-06 19:20:35 +02:00

This is related to Custom Split Normal Data. So there must be a problem in CustomData interpolation.

This is related to `Custom Split Normal Data`. So there must be a problem in CustomData interpolation.

notallowed commented

2017-05-09 10:10:15 +02:00

Hello,

well it's been quite some time now and I am wondering if this is being looked at or it's just not solvable at current state?

Thx!

Hello, well it's been quite some time now and I am wondering if this is being looked at or it's just not solvable at current state? Thx!

Bastien Montagne commented

2017-05-22 23:07:39 +02:00

Added subscriber: @mont29

Bastien Montagne commented

2017-05-22 23:07:39 +02:00

Changed status from 'Open' to: 'Archived'

Bastien Montagne closed this issue

2017-05-22 23:07:39 +02:00

Bastien Montagne self-assigned this 2017-05-22 23:07:39 +02:00

Bastien Montagne commented

2017-05-22 23:07:39 +02:00

Thanks for the report, but this is not considered a bug currently - custom normals are to be used as latest step, they are designed to handle well deformations of the mesh, but absolutely not changes in topology.

Thanks for the report, but this is not considered a bug currently - custom normals are to be used as latest step, they are designed to handle well *deformations* of the mesh, but absolutely not changes in topology.

YuanQing(Brent) Liu commented

2017-07-26 03:36:03 +02:00

Added subscriber: @BrentLiu

YuanQing(Brent) Liu commented

2017-07-26 03:36:03 +02:00

This may be working as intended(not a bug). But,

Baking a normal map requires the mesh to be triangulated to have the best possible result.

Having triangulate modifier is a way to keep the model workable(were still quads in edit-mode) while at the same time, previews/renders that mesh as triangulated.

3D modelling workflows for games uses custom normal very often, especially for low-poly models.

Now that this modifier wouldn't maintain the custom normals, to get the same level of result using such workflow become drastically slow due to manual processing of the triangulations. Or rather, the inability to go back to quads for back/forth editing & testing for the better result with different normal map iterations.

If I know CPython and was able to contribute, this will be my task. Badly I only started learning Python last year, and I haven't found a way to implement custom modifiers, I can only rely on Blender Foundation to help with this, for now.

If this can't be viewed as a bug, please, please, please, help us improve the triangulate modifier so it doesn't change the existing custom normals.

EDIT:

Actually, I just found a trick to keep custom normal using Data Transfer modifier, while moving the triangulate modifier above the Data Transfer... This introduces an extra object in the scene, but does the job pretty nicely. Kudos to BF this time!! But still, it would be nice to not having that extra object. ; )

This may be working as intended(not a bug). But, Baking a normal map requires the mesh to be triangulated to have the best possible result. Having triangulate modifier is a way to keep the model workable(were still quads in edit-mode) while at the same time, previews/renders that mesh as triangulated. 3D modelling workflows for games uses custom normal very often, especially for low-poly models. Now that this modifier wouldn't maintain the custom normals, to get the same level of result using such workflow become drastically slow due to manual processing of the triangulations. Or rather, the inability to go back to quads for back/forth editing & testing for the better result with different normal map iterations. If I know CPython and was able to contribute, this will be my task. Badly I only started learning Python last year, and I haven't found a way to implement custom modifiers, I can only rely on Blender Foundation to help with this, for now. If this can't be viewed as a bug, please, please, please, help us improve the triangulate modifier so it doesn't change the existing custom normals. # EDIT: Actually, I just found a trick to keep custom normal using Data Transfer modifier, while moving the triangulate modifier above the Data Transfer... This introduces an extra object in the scene, but does the job pretty nicely. Kudos to BF this time!! But still, it would be nice to not having that extra object. ; )

Bastien Montagne commented

2017-07-26 09:38:59 +02:00

Added subscriber: @RohanRathi

Bastien Montagne commented

2017-07-26 09:38:59 +02:00

@RohanRathi might be interesting to implement support of custom normals in a few modifiers like triangluate, if you still have time in your GSoC?

Rohan Rathi commented

2017-07-26 18:01:59 +02:00

Definitely could check it out.

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Triangulation Modifier breaks split normals #51117

EDIT: