Weight paint brush: front faces only not working. #75518

New Issue

Vyacheslav Kobozev · 2020-04-08T09:54:51+02:00

2020-04-08 09:54:51 +02:00

System Information
Operating system: Windows-7-6.1.7601-SP1 64 Bits
Graphics card: GeForce GTX 660 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 442.59

Blender Version
Broken: version: 2.83 (sub 11), branch: master, commit date: 2020-04-01 17:35, hash: a9963669f9
Also 2.82a broken
disabling and enabling «Front faces only» do nothing. Brush still paint backfaces.

2020-04-08_10-48-06.mp4

**System Information** Operating system: Windows-7-6.1.7601-SP1 64 Bits Graphics card: GeForce GTX 660 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 442.59 **Blender Version** Broken: version: 2.83 (sub 11), branch: master, commit date: 2020-04-01 17:35, hash: `a9963669f9` Also 2.82a broken disabling and enabling «Front faces only» do nothing. Brush still paint backfaces. [2020-04-08_10-48-06.mp4](https://archive.blender.org/developer/F8456350/2020-04-08_10-48-06.mp4)

Vyacheslav Kobozev commented

2020-04-08 09:54:51 +02:00

Added subscriber: @Vyach

Vyacheslav Kobozev changed title from ~~Weight paint brush: front facs only not working.~~ to Weight paint brush: front faces only not working.

2020-04-08 09:55:11 +02:00

Philipp Oeser commented

2020-04-08 11:27:34 +02:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2020-04-08 11:27:34 +02:00

Changed status from 'Needs Triage' to: 'Confirmed'

Philipp Oeser commented

2020-04-08 11:27:34 +02:00

Confirmed, checking...

Philipp Oeser self-assigned this 2020-04-08 12:21:39 +02:00

Philipp Oeser commented

2020-04-08 12:21:39 +02:00

Note this works with projected falloff shape (but spherical falloff shape is the default -- will check for a possible reason why this 'fails' with spherical falloff)

Note this works with projected falloff shape (but spherical falloff shape is the default -- will check for a possible reason why this 'fails' with spherical falloff) ![#75518.png](https://archive.blender.org/developer/F8456499/T75518.png)

Philipp Oeser removed their assignment 2020-04-08 15:25:59 +02:00

Philipp Oeser commented

2020-04-08 15:25:59 +02:00

Added subscribers: @PabloDobarro, @ideasman42

Philipp Oeser commented

2020-04-08 15:25:59 +02:00

This is something I dont fully understand tbh.
This also seems to be inconsistent between sculpt mode and vertexpaint / weightpaint.

Sculptmode seems to always use the StrokeCache viewnormal [even in Sphere falloff shape], see SCULPT_brush_strength_factor() / frontface()
Weightpaint / Vertexpaint either take the StrokeCache viewnormal [when in Projected falloff shape, but use the StrokeCache sculpt_normal_symm], see SCULPT_brush_frontface_normal_from_falloff_shape

So whenever you use spherical falloff together with FrontFace options (Front Faces Only / Front-face Falloff) in vertexpaint/weightpaint these will look like not working and still wrap nicely around your model or allow to paint on backfaces.
So whenever you use spherical falloff together with FrontFace options (Front Faces Only / Front-face Falloff) in sculptmode these will use the viewnormal [not sure if this has unexpected consequences somewhere?]

Imho (and also looking at the tooltips: Front Faces Only: "...that face the viewer" / Front-face Falloff "...face the front" [well, what is the front here?]), using these options should always use the viewnormal.
Or, using Spherical falloff should disable the FrontFace options?

relevant commits:
b2a10fa615
d8509b349d
6c43490616
8ef757df3

Not really sure what to do with this report (how to classify)

@ideasman42 , @PabloDobarro : opinions?

This is something I dont fully understand tbh. This also seems to be inconsistent between sculpt mode and vertexpaint / weightpaint. Sculptmode seems to always use the `StrokeCache` viewnormal [even in `Sphere` falloff shape], see `SCULPT_brush_strength_factor()` / `frontface()` Weightpaint / Vertexpaint either take the `StrokeCache` viewnormal [when in `Projected` falloff shape, but use the `StrokeCache` sculpt_normal_symm], see `SCULPT_brush_frontface_normal_from_falloff_shape` So whenever you use spherical falloff together with FrontFace options (`Front Faces Only` / `Front-face Falloff`) in **vertexpaint/weightpaint** these will look like not working and still wrap nicely around your model or allow to paint on backfaces. So whenever you use spherical falloff together with FrontFace options (`Front Faces Only` / `Front-face Falloff`) in **sculptmode** these will use the viewnormal [not sure if this has unexpected consequences somewhere?] Imho (and also looking at the tooltips: `Front Faces Only`: "...that face the viewer" / `Front-face Falloff` "...face the front" [well, what is the front here?]), using these options should always use the viewnormal. Or, using Spherical falloff should disable the FrontFace options? relevant commits: b2a10fa615 d8509b349d 6c43490616 8ef757df3 Not really sure what to do with this report (how to classify) @ideasman42 , @PabloDobarro : opinions?

Vyacheslav Kobozev commented

2020-04-09 13:02:56 +02:00

@lichtwerk
For Sculpt «front faces» means «not backfaces». And all over the Blender the same: backface vs frontface.
This why users expect to exclude backfaces, when they turn on this setting.

If «front face» will mean «faces in front of others» (z-index), there should be another aditional name, like «cut/ignore backfaces»

Also backface culling in workbench do not lock backfaces for weight painting.
I think, it should. Otherwise it is bad design to allow paint something, that you don`t see

2020-04-09_14-00-46.mp4

@lichtwerk For Sculpt «front faces» means «not backfaces». And all over the Blender the same: backface vs frontface. This why users expect to exclude backfaces, when they turn on this setting. If «front face» will mean «faces in front of others» (z-index), there should be another aditional name, like «cut/ignore backfaces» Also backface culling in workbench do not lock backfaces for weight painting. I think, it should. Otherwise it is bad design to allow paint something, that you don`t see [2020-04-09_14-00-46.mp4](https://archive.blender.org/developer/F8459553/2020-04-09_14-00-46.mp4)

Philipp Oeser self-assigned this 2020-04-14 15:12:22 +02:00

Philipp Oeser commented

2020-05-05 11:05:06 +02:00

Will get back to this shortly... Marking as Known Issue for now [since code kind of works as expected here -- already have green light though to change it to always use the view normal for vertex/weight painting]

Vyacheslav Kobozev commented

2020-05-05 16:33:48 +02:00

@lichtwerk okay, thanks!

Vyacheslav Kobozev commented

2020-08-26 01:28:38 +02:00

Poke. Sadly for weight paint it works like «any visible face» but for sculpt brushes it works like «for faces with similar normals»

Guys, can you swap em? :-)

Poke. Sadly for weight paint it works like «any visible face» but for sculpt brushes it works like «for faces with similar normals» Guys, can you swap em? :-)

John Sollows commented

2020-11-10 18:44:23 +01:00

Added subscriber: @Jern

Philipp Oeser removed their assignment 2022-01-18 21:20:22 +01:00

Philipp Oeser commented

2022-01-18 21:20:22 +01:00

Will have to concentrate on triaging for a while (and step down).

Philipp Oeser removed the

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Weight paint brush: front faces only not working. #75518