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 | 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. |
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