Optimizing a raytracer

[bearophile]

Róbert László Páli:

> And would you suggest to try to use
> SIMD double4 for 3D vectors? It would
> take some time to change code.

Using a double4 could improve the performance of your code, but 
it must be used wisely. (One general tip is to avoid mixing SIMD 
and serial code. if you want to use SIMD code, then it's often 
better to keep using SIMD registers even if you have one value).

Bye,
bearophile