Liquids and Soft Bodies Simulation
Up until now, the physics engine used by Physion was Box2D. Box2D is an open source 2D physics engine written in C++ and it is used in many games and apps.
Although Box2D is a mature physics engine with many features, it doesn't "natively" support fluid simulation. After some research on the web, I came across LiquidFun. As mentioned in LiquidFun's website:
LiquidFun is an extension of Box2D. It adds a particle based fluid and soft body simulation to the rigid body functionality of Box2D.
As it turns out, transitioning from Box2D to LiquidFun is quite easy. All the features supported in Box2D are also supported in LiquidFun so there's no need for any major code changes when switching to LiquidFun.
Although LiquidFun supports a rich set of features, we will start simple; the transition to LiquidFun will have one simple goal: Allow the user to convert a rigid body into a liquid or an elastic (soft) body.