Hi.
It is very common to see in forums that users ask about how to paint through the mesh so paint affects occluded part of the mesh, they having spent a long time on their own unsuccessfully trying to find the solution.
It turns out that in order to do this in Weight/Vertex mode, you have to apply a combination of two options that don’t say much about “paint through…”: Uncheck “Front Faces Only” and check the “Projected” falloff option. Until 2.81 this was a bit simpler (although still difficult and not intuitive) because both options (Front Faces Only and 2D falloff) were under the same drop-down menu, so a user could find the solution by experimenting with enabling or disabling different options in the drop-down menu. Nowadays it is even more difficult, because both options are in different menus.
Also, Weight/Vertex paint modes differs from Texture paint mode for this (although Texture paint mode is not user friendly either). So we have no consistency here.
What can be seen in the forums is that the user simply looks for an option “Paint through…” or failing that, to be able to do it when X-Ray mode.
So, would it be possible to have a Brush “Paint through…” option that automates the work for the user by configuring the corresponding two necessary options (disable “Front Faces Only” and enable “Projected” falloff?
Or any other user friendly solution will be welcome.
I would think for X-ray painting, you would just have it done by default when the backface culling button is turned off.
The reason for this, I don’t see the point of not painting backfaces when you can’t clearly see the surface anyway (which is the case when you see through the mesh), and it actually gives the appearance of broken design when you can clearly see faces (not masked) that can’t be painted. There might be a case to allow paint-through (via a checkbox) with culling turned on, but more likely then not the natural intuition I have assumes I want front faces only for most cases (unless otherwise specified).
The problems is front face weight display obstruct back face weight display, So there will be no good X-ray view when weights are displayed.
For cases like arms and legs it is needed to paint trough faces and weight round edge loops in one step.
I think terminologies like “Backface Culling” or “Falloff” or “X-Ray” are not really artist friendly for what the user is trying to achieve here. In addition, both in Wehigt/Vertex Paint or Texture Paint modes to achieve “painting through” the user has to modify a combination of two options to achieve it, which makes the matter even more unintuitive.
I have proposed a simple “Paint through” option because it is the terminology that the new user generally looks for to achieve the goal: https://www.google.com/search?q=“blender”+“paint+through”&oq=“blender”+“paint+through”
But perhaps there is even better terminology, the important thing is that it is artist friendly terminology and in a single checkbox to achieve it.
Edit:
Unchecked “Front faces only” as the only option to achieve this would also be artist friendly if it worked in a friendly way, but this is also difficult to understand and creates confusion as to how it actually works in Blender. https://developer.blender.org/T75518