Animate weight paint

Hello.

Been using blender for a few days and love it!

Now im trying to do some grass on a hill, but i want it to “grow” from the top and down. Now im using weight paint to get the grass on just the top part of the hill.

What im trying to do is set a key on frame 1 with just the top part green in weight paint, then on frame 30 i make the whole hill green though that dossnt seem to work.

is it possible to do anything like this?

Blender doesn’t have keyable weight paint (and probably wouldn’t know how to properly interpolate between painted keys). However, if you create an animated texture, you can apply it to the length your grass particles (I wouldn’t recommend using density… you might end up with magically appearing/disappearing grass).

However, if you create an animated texture, you can apply it to the length your grass particles

How do you do this with the new particle system? I don’t see it anywhere…

EDIT: Never mind, I found it in the Fields panel.

Thanks, if its not to much to ask for, could you write a step to step thing to get me started. I dont mean a full toturial, just something quick :slight_smile: I know how to use weight paint to control the length of my grass, but i dont know how to use a texture for it. I just see the “Vertex group”.