In the Smooth brush settings there’s a menu where you can switch the algorithm from Laplacian to Surface, then adjust some settings if desired.
The selected smoothing algorithm will be used when holding Shift while other brushes are active. I would desperately like to be able to use both algorithms without switching to the Smooth brush and opening the drop-down menu though. For example, holding Control + Shift could be Laplacian, and holding only Shift could be the Surface algorithm.
That is already the case.
There is a mode column to switch objects mode in outliner.
It was thought to support multi-object editing. Sculpt mode does not support multi-object editing.
But the column switches active object while preserving mode used.
There is also a Transfer mode operator mapped to Alt Q shortcut ; that allows to do that directly in viewport, to mesh object under the mouse pointer.
Thank you! @MetinSeven and @RonanDucluzeau for you answers!
@MetinSeven The surface-algorithm indeed enables a very controlled manipulation of the mesh-surface! And it would be very useful if blender made more use of the modifier keys to toggle an alternative smooth-mode (or to activate the masking brush which at the moment needs to be selected manually).
The subtle difference in the way the smoothing behaves that I ment (it can be experienced here: SculptGL - A WebGL sculpting app ) seems to lay in the “specific way of implementation”(?) of the laplacian algorithm. (Me as a non-programmer did take a look at the source code of SculptGL and found that also there it is called a laplacian smooth).
@RonanDucluzeau I did not know that it was already possible to switch the active object from the outliner!
Eventually this functionality could be altered so that selecting an object from the outliner while the sculptmode is active automatically deactivates the sculpt mode of the one object and activates sculptmode for the other?
Yes. Mode Column is on the left of outliner.
You have to click on the small dot into the column, not on the name of object.
Tested sculpt vertex paint today. There are two things I wish to have: protect alpha (now painting brush cover alpha) and protect color, when you paint with alpha brush:
I think, it is essential. First allow to keep contours and recolor them. Second allows to fix silhoette and keep color. Same way as separate alpha channel (or mask layer) in 2D
In vertex paint mode, color is preserved when alpha is erased and there is an Affect Alpha option in brush properties.
I think that would be great to have Affect Alpha as a mode option, too.
I think I saw a patch for the keeping of color when erasing alpha but probably hasn’t been reviewed yet
I only found this one to separate alpha and strength in brush properties.
https://developer.blender.org/D8175
There is no design task talking about alpha for Sculpt Vertex Colors.
Blending modes were just copied and pasted.
It seems that issue is mentioned nowhere.
https://developer.blender.org/D12587
Not sure if that is it but its in that branch that will be merged later
I just discovered that the Trim tools don’t respect masking. That’s quite a handicap. It would be great if this could be added.
I guess the Trim tools work by internally generating an extruded mesh from the shape that’s drawn with the Trim tool, then Boolean subtracting that from your model. Taking masking into account would probably complicate generation of the invisible Boolean subtraction mesh.
A workaround could be to skip masking support for the Trim tools, but support hiding or Alt + B isolation of separate parts that wouldn’t be affected by a Trim operation.
How I’d love to be able to perform non-destructive Signed Distance Fields sculpting and coloring inside Blender.
Here’s a method using Marching Cubes in Geometry Nodes:
It might work a lot faster if OpenVDB would be used.
Metaballs are SDFS. And they have remesh system much faster than voxels.
Why the stamp system should be reworked in Blender (sculpt/paint)
RCS suggestion:
Unfortunately they are just metaBALLS, not metaMESHES, so you can only have a few specific default primitives 
Not that useful.
There is tradeoff.
You can use good engine and smooth transition with SDFs, and lay the surface exact at the level.
Or you will have bumpy surface with mesh-SDF and voxels.
Voxel remesher exist already.
The other possibility is to trace mesh-sdf not from its points and not from distributed points but right from faces. BUT idk if there is a paper, that suggests high-perfomance calculation for this way. I suppose, something nice for low-poly exist.
Yup, it is better. I even made my own profile erlier
But it is still not so sharp, and it is still only displacement, without option to make real «cut» in surface. Compare:
Yeah, but metaballs in Blender are limited and have barely been developed during the past years.
