Tips and Tricks: Liquid in a glass

Rendering a liquid inside a glass or bottle

A liquid inside a glass or bottle is one of the most tricky subjects to render if you want to get all the subtle effects that happen in the real world in this kind of scenarios, specifically the correct TIR (total internal reflection) and the surface tension meniscus. 

Maxwell can accurately get that exact results but you will have to take into account a couple of things. 

Instead of creating a double sided glass model (that could not get the proper result in the planes where the inner glass and the liquid meet), you will have to create a full body of glass and place the liquid inside, to avoid the wrong TIr you would get if you used two different surfaces.

The following scheme shows the proper way to model this subject. 

Keep in mind the infinitesimal gap in the upper surfaces, just enough to avoid having the two surfaces in exactly the same position. 

Correct way to model a liquid body enclosed on a glass or bottle