The pattern node presented here can be used to "cull" objects by connecting it's resultMask output to the presence input of a material. The node reads the value of a user (float) attribute associated with each object. For example.
Attribute "user" "float probability" [0.8444]
It is assumed the attribute values are random and are in the range 0 to 1. The value of the "Presence Threshold" determines when the attribute value will cause the plugin to output resultMask values of 0 or 1 for the geometry being shaded.
The following animation shows the effect of the culling when applied to 500 nurbs planes. The geometry was created by a procedure called gen_random_planes. The value of the "Presence Threshold" was keyframed from 1 to 0.
Each of the planes were assigned a float attribute called
Attribute "user" "float probability" [0.881849647]
© 2002- Malcolm Kesson. All rights reserved.