You can use the imgui controls to change scene.
The raytraced volumetrics are in the Volumetrics scene, but do note it has performance
issues on web! It runs smoothly on Linux :)
Summary
As a research project, I expanded a university assignment where we write a CPU raytracer to also
support volumetric smoke. I used a raymarching technique to step through voxels of smoke, and
cast reflection rays to calculate lighting via Beer's law.