Add an option that prevents paint from going through surfaces when painting#1296

Right now when painting things like capes as far as I can see there is no option to prevent paint from going through to the underside of a surface. My IRL painting style uses layer highlights near exclusively because I just like manually blending and building up colour transitions but because paint currently effects both sides of a sufrace when applied I can’t paint minis with things like capes in my artstyle as the underside ends up inverted with no way to correct it without ruining other parts of my work. From what I’ve seen this is less of an issue if you use the drybrush tool but that just isn’t how I want to paint as it doesn’t give the stark contrast I like on my models.

think of the paintbrush as a sphere instead of a circle. It paints on all surfaces within it’s sphere. So there are two ways to paint 1 side of a cape:

1. Make the brush small enough that the sphere doesn’t go through to the othe side, or,
2. use the airbrush tool which paints directionally.

I managed to figure that out on my own but I found the airbrush can actually still go through in the deeper folds and I’m not particularly enthusiastic about painting with a tiny brush for areas that big so I think I’m just not really going to be using the mini painter until something is done about this.