Anyone familiar with painting miniature models knows the value of dry brushing - going lightly over a model with barely any paint on the brush so that only edges pick up paint. It is often combined with color washing to great effect.
Given Blender’s excellence in digital sculpting, it would be wonderful to bring Dry Brushing to Blender’s paint modes.
Imagine while vertex painting you could toggle Dry Brushing Mode. When Dry Brush was enabled, not only the brush shape and weight would be used to calculate coverage, but also the concavity of the vertex and it’s ambient occlusion. The concavity would be calculated by comparing the normal at the vertex to the neighboring normals. If the neighbors point away, the Dry Brushing factor would be increased, as this would indicate an exposed edge. Low occlusion would also increase the Dry Brushing factor. Values should fall off rapidly so that only the edge is picked up, but this value could be user-adjustable.
A related mode would be Color Wash, which would do much the opposite. It would modulate the brush amount for high occlusion and normals pointing in. This would mimic the way thin paint or ink pools in creases and recesses.
These techniques could be used to paint directly, or I have had great results painting material masks for use with Cycles nodes. For instance, I will Vertex Paint the edges of a model and then use that value as in input to a Mix Node in Cycles with a subtle variation in materials. It looks even better when the material mask is multiplied by a noise pattern first.
Any thoughts? Would this be useful to others as well? Anything I’ve overlooked?
What I’m describing is similar to a Cavity shader, but with more artistic control. For instance, you might want brush strokes to appear on your edge. Or you may want to do Texture Painting instead of vertices.
I currently use the Dirty Vertex Colors and then mess with them from there. But it would be much more convenient and allow more artistic expression if the tools supported it directly. I believe Maya has an option similar to this.
EVERY modern 3D painting app has tweakable real time cavity masks for paining models. One of the reasons I still don’t use Blender’s painting tools in production.
EVERY modern 3D painting app has tweakable real time cavity masks for paining models. One of the reasons I still don’t use Blender’s painting tools in production.
it is a good reason.
Using, 3dcoat and zbruh, they both have mask by cavity.
I wonder, can normal maps be used to calculate cavity?
It’s a rather expensive method though.
in multires, while painting models, res levels not too high not too low, use the normals in the option tab set at something like to 15 or 10 degrees, would emulate the process but view dependent of course, a little touchy but could work.
It seems like there is agreement this would be a useful tool. Will a thread like this be enough to get the dev team to consider adding it? Or is something more “official” required?
