public void draw(float innerRadius,
renders a partial disk on the z=0 plane. A partial disk is similar to a
full disk, except that only the subset of the disk from startAngle
through startAngle + sweepAngle is included (where 0 degrees is along
the +y axis, 90 degrees along the +x axis, 180 along the -y axis, and
270 along the -x axis).
The partial disk has a radius of outerRadius, and contains a concentric
circular hole with a radius of innerRadius. If innerRadius is zero, then
no hole is generated. The partial disk is subdivided around the z axis
into slices (like pizza slices), and also about the z axis into rings
(as specified by slices and loops, respectively).
With respect to orientation, the +z side of the partial disk is
considered to be outside (see gluQuadricOrientation). This means that if
the orientation is set to GLU.GLU_OUTSIDE, then any normals generated point
along the +z axis. Otherwise, they point along the -z axis.
If texturing is turned on (with gluQuadricTexture), texture coordinates
are generated linearly such that where r=outerRadius, the value at (r, 0, 0)
is (1, 0.5), at (0, r, 0) it is (0.5, 1), at (-r, 0, 0) it is (0, 0.5),
and at (0, -r, 0) it is (0.5, 0).