Volumetric Cloud

Volumetric rendering has always been a topic I'm intrigued in. These gorgeous effects like godray, volumetric cloud and mist can offer the player a strong sense of immersion.
There are many approaches to realize volumetric cloud, like modelling, billboard, and Ray Marching. Personally, I prefer the Ray Marching method.

The brief idea is:
(1) Draw a box cloud using Ray Marching
(2) Calculate the intersection and occlusion using bounding box (like AABB, OBB, etc.)
(3) Use Worley noise to simulate the cloud's shape
(4) Calculate the light transport in volumes using Beer-Lambert Law and HG phase function, so as to simulate physical phenomenon like absorption, in-scattering and out-scattering.
(5) Customize the shape and movement animation of clouds.

Currently, many game studios are trying to add this technique into their games. For example, Guerrilla Studio shared their implementation of volumetric cloud in SIGGRAPH talks, and it also inspired me to optimize my implementation in my graduation project.

***You can click on the video at the botton to view its effect***