[the__alchemist]

Good timing - I was procrastinating on HN instead of trying to fix my phucked-up phong; you've helped me do both.

[sysrpl]

With a good phong it's all about the dot products and specular highlight (if you using highlights). Make sure you clamp the dot products and give yourself a minimum ambient light value of around 0.15 to 0.2.

[Jasper_]

The thing that got me, in a classic Phong, you have to test whether dot > 0.0, it really won't work outside of the front hemiphere. The clamp isn't enough.