This weight paint/vertex group controls particle hair distribution. I want the hair line to be more abrupt. How can I change the falloff of the edge so it is sharper? That is, the outer edge of polygons has more red and thinner yellow and green.
It’s the sharpest, it just creates a gradient between a vertex and the next but the next one is zero
I’m asking how to change that gradient. If it can’t be changed then Blender is lacking a useful function.
Various falloffs can be selected for painting with brushes. I don’t want to paint with a brush but instead to change the gradient on this existing weight map. We should be able to change the rate/shape/curve of that falloff or gradient.
The goal in this particular instance is to make this character’s hairline thicker. That is, the fade from dense hair to bare skin would occur more suddenly.
use blur tool for that…but if you want a decrease of the length of the hair of that falloff of the weight, you cant because the weights are for assigning in specific points on your model for the hair to be put on, So you have to do that manually with the hair particle editing brushes to decrease the length of the hair…
Vertex groups are vertex groups, not face corner groups like e.g. UVs. Vertices are shared between faces, so weights should be interpolated between neighboring vertices. If you want an abrupt transition, you can extract a skull cap just for the hair and make it all have weight of 1.
“If it can’t be changed then Blender is lacking a useful function.” The artist should be able to control the falloff – the interpolation between vertices. Agree: The separate objects method for hair is great. It has many merits including overcoming this problem.
Unfortunately, with the vertex group on the character as it is here the border falloff zone is not even part of the vertex group …
The falloff border zone is not inside of the vertex group. Group is selected showing in orange. The artist has no ability to change this gradient or falloff. For example to have more yellow and less green.
Separate objects as hair emitters allow falloff control at the edges and do not leak beyond it as happens above. These hair particles have density and length controlled by weight maps. I made a vertex group for density and another for length. Each includes the entire plane. The plane has many polys/faces. I used a gradient weight across length vertex group to taper the length on the left side and painted a less-than-one weight swath through the middle of the density group.
So the problem is best solved by using separate hair emitter objects. That is probably the best way to do hair for other reasons too.