Number of Polygons...?

OpenGL OpenGL: Basic Coding
1

Can I know the number of polygons that are actually rendered by OpenGL?

For example, If I try to render 100 polygons and 10 polygons of them are clipped by view frustrum culling, then the number of polygons that are actually rendered by OpenGL is 90. Is this right? Then How can I know the number of actually rendered polygons?

2

There’s no way to get this number from OpenGL.

3

I disagree. This is what the selection buffer can deliver along with other informations. Look up examples on glSelectBuffer() and glRenderMode().
If you ask this with performance enhancements in mind, than better don’t use selection.

4

Oops, forgot about them, but as you say, you better not use them if you care about performance