Porting Spheres

When porting spheres to OpenGL, keep the following points in mind:

You cannot control the type of primitives used to draw the sphere. You can control drawing precision in another way: use the slices and stacks parameters. Slices are longitudinal; stacks are latitudinal.
Spheres are drawn centered at the origin. Instead of specifying the location, as you do with the IRIS GL sphdraw function, precede a call to the GLU gluSphere function with a translation.
The sphere library is not yet available for OpenGL.

The following table lists the IRIS GL functions for drawing spheres and their equivalent GLU functions where available.

IRIS GL Function	GLU Function	Meaning
sphobj	gluNewQuadric	Create a new sphere object.
sphfree	gluDeleteQuadric	Delete sphere object and free memory used.
sphdraw	gluSphere	Draw a sphere.
sphmode	—	Set sphere attributes.
sphrotmatrix	—	Control sphere orientation.
sphgnpolys	—	Return number of polygons in current sphere.