primitives in chops

[Rudinie]

I'm trying to drive the extrusion of a bunch of polygons and what i've got so far is working but it's too lineair to my liking. The way i've done it so far is with an expression, i added an attribute to the primitives (polygons) with a AttribCreate SOP and put an expression on it: min(1,max(0,($T-(1.5*rand($PR)))))* (1.3 + 0.1*rand($PR))

This attribute is used in a polyExtrude Sop.

This way the extrusion grows over time and is random over time and extrusionlength but the movement is just simply lineair.

In the chops tutorial on the SideFX forum the tutor says to allways try to input points to chops, not primitives. But then how could i use chops to drive the extrusion of my polygons?

Hopefully someone could shed some light on this for me as i'm fairly inexperienced with chops.

Tnx in advance.

[Rudinie]

I found a way to do what i wanted, allthough i'm not quite sure it's the easiest way. What i did was create a popnet to get one particle on the center of each prim. After the popnet i created the attribute i needed (extrudeZ) so i can change this in chops. After chops i used attribtransfer and a attribpromote to get the point attributes back on my prims. Works fine and i love the power chops offers but is it the cleanest or easiest way, i doubt it.