Hemisphere <radius> <density>
This command creates a hemisphere of the given dimensions in the current clump. The hemisphere is transformed by the current transformation matrix and its surface is assigned the current material.
The density controls the number of polygons used to approximate the hemisphere. It cannot be negative. A density of 0 results in a pyramid. The number of polygons varies exponentially with the density.
The radius can be either positive or negative. It cannot be zero. A negative radius creates a hemisphere that is "inside out" (i.e. only visible from the inside).
<radius> the radius of hemisphere
<density> the density of the hemisphere