If I have a model, for instance UV unwrapped, how can I from a texture assign a vertex group. White = assign vertex, black = don't assign vertex, values in between = halfway assigned vertex based on color intensity. A grayscale image would probably be used.
You can try the Vertex Weight Edit modifier. For example, I can input the following texture as a Texture Mask to the modifier:
... that will then use its value, to control how the modifier assigns weight to each vertex. Tweak at least the Default Weight, threshold settings and fallof type to get the result you need:
Though not instantly updated if we edit the image, the result shows up immediately, and is usable by modifiers further down the stack:
Default Weight and Add Threshold should be of that weight which you'd like to have as the end result, Add Threshold should be slightly less.
I have a solution that works but is annoying:
- Create a new vertex group, and in Edit Mode assign all vertices to the group.
- Back in Object Mode add a VertexWeightEdit Modifier
- In the Falloff Tab create a custom curve and move the right point to 0.
- In the Influence Tab add the texture you've already created.
What this does is subtract the texture from the 100% weight of the original group. This means the final selection is the inverse of what you want: lighter parts of the texture are the least selected. So any time you use the Vertex Group you have to enable the invert button (Looks like this: <-> ) to get the result you expect.