Vertex group controlled materials.

Hi. I am about to start a large project making terrain, but before I begin I want to get this workflow issue straitened out. My question is, how does one use a vertex group like what you would use to control particle density to also control the material where you have painted?

Example: I want to paint the side of a mountain with a vertex weight to add the ‘rock particles’ (which I can already do) while also applying an underlying dirt material, and in another location, using a different vertex group, paint and create grassland with the appropriate spawned grass particles and material. (Again the particles and hair I can already do)

How might I do this? I have been messing around with the Vertex Weight Edit and Vertex Weight Mix modifiers, but I cannot get them to do anything. Should I be using these or a different approach.

Also, is using vertex groups for this the best approach? The subdivision surface on my terrain should smooth out the transitions if I can make the vertex groups a weighed mask, but if that is not the case, what about using a texture mask to control the vertex group. I haven’t found anything useful on the internet on how to change textures into vertex group weights, so I don’t really know how I would do that.

Thanks in advanced.

Instead of using vertex weights you can use vertex colour to influence the mix of two textures.

For cycles renderer you can use an Attribute node with the name of the vertex colour layer and use that to the mix factor between two textures

For Blender renderer you can do a similar thing with node materials using the vertex colour name in the geometry node

You could also just use a painted b+w image texture

That’s really helpful because I did not know you could do that with the attribute node, but then that begs the question of how would you control particle density doing that. It seems like any one means of controlling particle density or texture masking excludes the other (I.E. can only control particle density and no texture masking, or the other way around.) I am looking for something like what you can do with the Blender internal renderer and use an image as a mask for the materials and control the particle density.

Bake the vertex colour to a b+w texture and use for both controlling mix of textures and particle distribution. As per the above but use texture in place of the vertex colour

Okay. Thanks. I will give this a try, and I might just try a workaround with the Blender internal engine as well to see which I prefer. Though one would expect a more direct method than this to be available in such a developed piece of software.