Use of Low-Precision floats in Mobile Shaders breaks materials! (Affects Default Engine Materials)

[RVillani (Rod Villani)]

@anonymous_user_fbe2d247

Keep in mind that everything that is calculated at vertex shader uses high precision by default. So most of the time you can get away without forcing full precision by calculating most of the stuff at vertex shader. Also with carefully trying to stay in half float range you can get away even in pixel shader. In your example normalize is the prolem. Absolute world position using centimeters so values are usually quite big. Max half float is 65504. Normalize is doing division by lenght of vector. So its xyz / x^2 + y^2 + z^2. So if sqrt of x,y or z is over sqrt(65504) ~= 256 which is just 2.56meters you get overflow. Just by premultiplying vector before normalization can get you in proper range and everything is fine again.

Awesome explanation, @anonymous_user_fbe2d247. Thanks a lot! I’ll keep that vertex full precision info in mind. I already do a lot of stuff in vertex to save on processing power, even Fresnel.
I suppose you are exactly right about the problematic distance. In the projected objects that seemed to be the start distance of the projection problems.