How Can I Control Particle Placement Using an Alpha Mask?

Hi, I have a grass plane using particles and I want to use an alpha image to Control the Particle placement? (See image 1)

(image 2) Shows the alpha image I want to use to control the shape of the grass.

(image 3) Is the result I want.
In Vue you can use an alpha image to control where grass and other objects go. I thought maybe in the particle settings there would be an option to load an alpha image to control the shape of the grass emitter, but I didn’t see anything.

How can I control Particle Placement Using an Alpha Mask?

When you have a particle system you then have the option available to add a texture to influence various properties of the particles system such as density/hair length etc. It is the same as using vertex weights on your particle system but with a texture.


particle_texture.blend (145 KB)

Thanks Richard.

I did get some success but I don’t know how to get rid of the green color around the edge of the particle emitter. I guess I need to add the circle alpha to that too but I am unsure how.

The particle emitter is green to control the grass color and if I set it’s transparency to 100% then my grass get’s totally transparent too and is not visible.

Create a new material slot. Change material to what you want the plane to be. Select all of plane in edit mode and hit assign under your material. For the particle system just make sure that ‘material’ is set to the original green material, in this case material 1.

Thanks Richard and Adey1981, So I got the grass to clip. Thanks. :slight_smile: I don’t understand why I have to “assign” the material to the plane. Shouldn’t this be automatic?

So how would I add or carve a path into the same grass? I added a third material slot and then added a path alpha image but it seems like the plane will only accept the top material? What to do?