Is there a tool to erase out or reduce delta from a shape key? Like Morph brush in zbrush or Erase brush in Mudbox?

Question

When you are using many shape keys for your sculpting, you can decrease the value of a shape key to reduce your sculpt amount. But it will apply same value reduction on all the sculpt in the shape key. I want to tastefully erase only some of the sculpt in the shape key. Is there a way to do this interactively?

In zbrush, your can store a morph target, and use morph brush so that your sculpt can go back to the stored sculpt and your pen pressure will determine how much you can go back to it so you can choose which sculpt to keep and how much. In mudbox, there is a erase brush you can use it on a sculpt layer, and again your stroke and pressure will determine how much sculpt in that layer to be erased or reduced.

I do not see anything like that in blender.... If you are doing very sensitive and artistic sculpting, it is very nice to mix multiple layers of sculpt just the right amount..... I am surprised that there is no equivalent tool for blender that all the other major 3D sculpting sofewares have....

Answer 1

Yeah, you can do that. It involves different tools. To me, it doesn't sound any more complicated than your description of Z's tools, but it will probably take getting comfortable with other elements of Blender before it feels that way to you.

What you do is create a vertex group to modulate your shapekey. If you're already comfortable with weight painting, that's easy enough. If you're not-- well, it does take people some time to get comfortable with weight painting.

Below the shapekey value, there is a field to enter a vertex group to modulate the shapekey-- I'm hovering my mouse over that field so you can see the tooltip. That will blend the shapekey according to any weights we've painted for that vertex group, as demonstrated by comparing the shapekey on the left (unmodulated) with the shapekey on the right (modulated by the vertex group shown.) It's the same shapekey.

If we'd like to write this to a brand new shapekey, that builds that vertex group modulation in, we can use the shapekey specials and do a new shape from mix. That will respect any VGs set for any shapes we've got mixed in.

Another useful tool is blend shape from mix, in edit mode, which will add or replace the shapekey vectors of any selected vertices with any other shapekey, but that's not "soft" across the mesh, not the way that vertex groups are. (You can still blend at 0.1 or 2.0 or whatever, so it's soft in that respect.)

Weight painting isn't hard, and is useful for a lot of modelling tasks, although people generally first encounter it when working on animation tasks like armature deformation. For this vertex group, I just alt click dragged across the mesh to make a linear gradient. Although I'm not certain those hotkeys are the same as yours. Most of my weight painting involves either linear or radial gradients on Add or Multiply mode. Making a quick VG like this is pretty easy when you've done it a few times.