Global particle position affect HaloSize?


I was wondering if there was a way to have the global postion of a particle affect its HaloSize?
Im currently trying to create something that looks like a dustcloud that would be propelled out in a bullet impact on a concrete wall. What seemed so easy turned out to be pretty tough… or i turned out being incapable of using Blenders Particlesystem properly, choose what you like better. Anyways, to create the shape of a cone for, the cloud I emmited all particles in one frame and had them have 2 offsprings with maximum random life. I would have prefered something like a random Normalspeed or a random damping, using the availble random function only resulted in a weird cube being formed.
I then used the Ipo curve to increase Halosize and decrease Haloalpha over time, but since the bottom particles were older than the top ones it didn’t turn out very coneshapey (:rolleyes:).
So now I wanted to try to use the particles location to additionally control their size. I was thinking of the Material Node Editor and its Global value in the Geometry node, but the Output note has only a color and an alpha value. I think there should be a way to affect all the other values you can manipulate with the Material IPO using the node editor…
My solution for the problem seems pretty weird to me so, apart from my original question, I would be very grateful for other Propositions. :slight_smile: