Particles driven by Stencil

Support Particles and Physics Simulations
1

I’ve created a very simple ground landscape material using two textures (grass and dirt) mixed by a stencil, as explained here (http://feeblemind.org/blog/index.php?post/2005/02/27/16-didacticiel-usage-des-masques-de-textures-tutorial-using-texture-stencils)

It looks nice, but using particle grass it would look even better. The question is: can I use a stencil to define the regions in which the particles must be shown?
I know that I can create a particle grass and use the Vertex Group to define the grass regions, but the use of a stencil would make it easier.

2

If you have a prticle system you’ll then have an option in the texture panel to add a particle texture. This can be set to then influence various particle parameters such as particle density / hair length etc

3

Thank you Richard, you’ve been very quick!
I’ll take a look as soon as I’ll be back home.

And… can i do the same think using a grass patch (mesh) like this http://www.blender3darchitect.com/2009/09/free-grass-patch-for-external-visualization-with-luxrender-and-blender-3d/?
In other words, let’s say I use this mesh grass patch and duplicate it so as to cover a big landscape surface. Is there a way to use a stencil to define the regions of this big mesh to be shown/hidden?