Hi Phillip, yes. You can use any texture to control the particle system. Not only the density, but also for instance the length of the hair can be controlled by a texture. In the particle settings panel, almost at the bottom, open the one named Textures and click New. Then on the right, next to the x, there is this icon looking like two sliders or whatever: click that. Now you are in the Textures panel where you can put in your texture. This will be controlling your Particle system. Then at the bottom, just above the Custom Properties, you can see Influence. Open that up and under General, click Density. That’s all. You can go back to your particle settings and tweak them to your liking.
