boxed pattern creates a 2x2x2 unit cube centered at the
origin. It is computed by: value =1.0- min(1, max(abs(X), abs(Y),
abs(Z))) It starts at 1.0 at the origin and decreases to a minimum value
of 0.0 as it approaches any plane which is one unit from the origin. It
remains at 0.0 for all areas beyond that distance. This pattern was
originally created for use with
it may be used anywhere any pattern may be used.