# Chapter 18 Further Reading

[Tutorial of Ray Casting, Ray Tracing, Path Tracing and Ray Marching](http://blog.ruofeidu.com/tutorial-of-ray-casting-ray-tracing-and-ray-marching/)

[modeling with distance functions](http://iquilezles.org/www/articles/distfunctions/distfunctions.htm)

[Random Noise](https://www.raywenderlich.com/70208/opengl-es-pixel-shaders-tutorial)

[NUBIS: REALTIME VOLUMETRIC CLOUDSCAPES IN A NUTSHELL](https://www.guerrilla-games.com/read/nubis-realtime-volumetric-cloudscapes-in-a-nutshell)

[Dissecting “Tiny Clouds”](https://blog.demofox.org/2017/11/26/dissecting-tiny-clouds/)