Linear "cracks" spaced evenly throughout the viewing frame. With
each additional "step" more cracks are superimposed.

The options are as follows:

steps

valid values are whole numbers from 1 to 20.

steps density

valid density values are whole numbers from 10 to 500.

EXAMPLES

fissure 4 500

fissure

In the first example, 4 layers of cracks with the (maximum)
density value of 500 are drawn. When no argument is given, 1 set of
cracks is drawn with density value 400.