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||Creates a new sphere object.|
|sphfree||gluDeleteQuadric||Deletes sphere object and free memory used.|
|sphdraw||gluSphere||Draws a sphere.|
|sphmode||Sets sphere attributes.|
|sphrotmatrix||Controls sphere orientation.|
|sphgnpolys||Returns number of polygons in current sphere.|