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View Full Version : What is half angle vector???????

chamberdx
10-12-2001, 03:06 AM
What is half angle vector can anybody tell me?? I know that it is used in lighting calculation but I haven't looked into it..just yet..

any help is appreciated

cheers

harsman
10-12-2001, 06:25 AM
The half angle vector H is 0.5(V+L) Where V is the view vector and L is the light vector. You then compute specular lighting by using H dot N. It is used in e.g. the OpenGL lighting equation mostly because of it's efficiency. If the light is directional and the viewer is at infinity, H is constant so you only have to compute is once. Try searching google for "lighting equation" with "blinn" and "phong" and you should get some relevant pages.

chamberdx
10-12-2001, 03:44 PM
thanks alot
but...ahh
Im still see it vaguely.. could you help me visualize it please like what exactly half angle vector does... or any articles on that if you dont wanna waste your time telling me...

cheers!
http://www.opengl.org/discussion_boards/ubb/smile.gif

Nutty
10-14-2001, 05:08 AM
I found this. http://www.whisqu.se/per/docs/graphics10.htm

A most excellent description on Blinn Specular. And _why_ the half angle is used.

Nutty