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Maniphest T92909

Texture Alpha Invert not working
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Description

System Information
Operating system: Windows-10-10.0.19043-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 2060 SUPER/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 472.12

Blender Version
Broken: version: 3.0.0 Beta, branch: master, commit date: 2021-11-05 22:17, hash: rB7a5b8cb20284
Worked: (newest version of Blender that worked as expected)

Short description of error
Texture Properties Alpha invert doesn't work

Exact steps for others to reproduce the error

  1. Go to Texture Paint
  2. Go to brush settings menu, then create a new texture mask
  3. Go to Texture Properties tab, and load an alpha image "black and white to use as brush texture"
  4. go to alpha menu in texture properties tab and click invert, that doesn't affect the brush or the alpha texture loaded in

PS. check the whole Alpha menu " Calculate, invert..." it seems that nothing work, but most importantly the invert

Event Timeline

Shady Hamza (Shady.Hamza) created this task.Nov 7 2021, 7:15 PM
Shady Hamza (Shady.Hamza) added a comment.Nov 7 2021, 7:25 PM

it should invert the black and white values

Philipp Oeser (lichtwerk) changed the task status from Needs Triage to Needs Information from Developers.Nov 8 2021, 1:08 PM
Philipp Oeser (lichtwerk) added a project: Sculpt, Paint & Texture.
Philipp Oeser (lichtwerk) added a subscriber: Philipp Oeser (lichtwerk).

As far as I can tell, alpha values of the texture (when being used as a Texture Mask) are not used, just the intensity (calculated by the luminance of rgb -- which is not directly altered by the alpha).
So while inverting the Alpha does make a difference when using an alpha texture for the Texture of a brush, it does not when using it as a Texture Mask (again, flipping alpha does not alter the values directly).
This sounds like intended behavior, to be 100% sure, I'd like a Sculpt, Paint & Texture dev to confirm though.

To invert the Texture Mask values, I would assume using Colors > Color Ramp and flipping the color stops is the way to go?

Calculate seems to work for me btw. in case it does not, please provide an example .blend file with that image packed.

Shady Hamza (Shady.Hamza) added a comment.Nov 8 2021, 2:01 PM

The Alpha check box and calculate option seem to work fine, the calculate activates the color ramp where i can invert the black and white yup, thanks for pointing that out :), but till now i can't figure out how or when the invert work, are you saying the invert works by inverting the rgb channels luminance of an image. if used only with brush mask? and the rgb colors if used in brush texture? i've tried uploading a colored image to the brush texture but it affects the luminance only if that's the case then it works i guess

Philipp Oeser (lichtwerk) added a comment.Nov 8 2021, 2:15 PM
In T92909#1250323, @Shady Hamza (Shady.Hamza) wrote:

but till now i can't figure out how or when the invert work,

Try this file (it uses an alpha texture as Texture [not as Mask Texture], Invert seems to work fine (it does not touch the colors, but flips the areas that are painted).

T92909.blend3 MBDownload

are you saying the invert works by inverting the rgb channels luminance of an image. if used only with brush mask? and the rgb colors if used in brush texture?

It never inverts rgb, it inverts alpha.
When using an alpha texture as Texture the area were painting takes place is determined by its alpha
When using a Mask Texture the area were painting takes place is determined by the luminance of the Mask Texture rgb

Philipp Oeser (lichtwerk) closed this task as Archived.Nov 8 2021, 2:50 PM
In T92909#1250331, @Philipp Oeser (lichtwerk) wrote:

When using an alpha texture as Texture the area were painting takes place is determined by its alpha
When using a Mask Texture the area were painting takes place is determined by the luminance of the Mask Texture rgb

Actually, after inspecting code a little, I do think this is all working as intended (like described above), so really dont think this is a bug, will close.
(but of course feel free to comment again if issues persist)