How to determine the normal vector to the plane of sight in OpenGL?

Question

I'm working on a kind of camera orbiting function for an application and I need to know the normal vector to the plane of sight. I think it might be the same as the line of sight vector, is it? I didn't know how to explain, so i did a little drawing:

img http://img714.imageshack.us/img714/6233/explanationo.jpg

Answer 1

You know vector that points forward (not "line of sight", just "forward")? You know, from camera position? "Normal to the plane of sight" points backward. And that's it.

Also, graphic editors normally has "text" tool that produces much better results than handwritten text. As a general rule - unless you have graphic tablet, your text editor has pressure sensitivity and your handwriting is perfect, you should use the text tool.