Using simple physics, we can easily create an interactive liquid surface.
The most natural representation of a liquid such as water is a particle system.
The Tron (1982) movie, in addition to inspiring me and a lot of people of my generation when we were younger, was also a pioneering effort for computer-generated graphics in film.
Ken Perlin, who worked on Tron was frustrated by the "machine-like" appearance of the models in the movie, and then he developed a method of creating textures with a mathematical algorithm that could be applied to images to introduce that random quality that real world has, less perfect computer-generated imagery.
These procedural textures can be used to lots of things, but I focused on a way generate smoke,fire and water surfaces.
When I had to replicate the 80's lava lamp object, my first thought, was to create a complex particle system, and use the drawing api to draw a gradient simulate the plasma effect, but after a while, I found that using blendModes,combined with gradient colored circles, simplify the problem to the limit.
Blend modes are conceptually very simple, but their practical application is sometimes difficult to see, and really often does result only from a bit of luck and guesswork.
( A biological texture generated with blend modes )