Lighting on 3D Objects

Introduction

I had a hard time coding 3D lighting of a diamond-like object built out of (triangular) facets. Not that the code was giving me headaches, but my math skills are quite rusty ;-) The results of my findings are in this tutorial. I'll show you how to code the lighting of an object by a pinpoint light source moving over a sphere.
No stress, I'll help you recall the trigonometry basics and illustrate the steps along the way. I however will assume some knowledge of flash, like making MCs, functions, the attachMovie scripting (+linkage), etc.

First play around with the my result of the adventure in math to come ;-)

PS. The light source can be set to manual: it'll then follow your mouse instead of following the path of a deltoid. Use the menu.

Next chapter I'll explain how to visualize the point you'd want your light to be most fierce, then we'll go over the math. After that I'll discuss chunks of code and we'll end with the whole script.