"Fields" Branch Physics Solver for Blender 3

In the new "Fields" proposal here code.blender.org/2021/08/attributes-and-fields/ , if the "Attribute" data of each and every vertex, edge, etc can be user defined, then you have the basic structure of a physics solver.

For example, all a rigid body solver really does is take the "attributes" of an object (dimensions, volume, mass, etc), calculate the center of mass and update the position, velocity and angular momentum based on any external forces or collisions if present. It's just code doing calculations on "internal" attribute data reacting to "external" attribute data.

To allow the new "Function Nodes" to become physics solvers, they would need the ability to solve and store the new "Attributes" for position, acceleration, etc for that specific kind of solver.

For example, a solver could calculate "wind" or "magnetic" forces and a different solver further down the pipeline could solve for buoyancy, then another for collisions, etc. That way, rigid bodies, fluids, particles, etc could get processed in a unified way by different solvers as the data makes it way through the pipeline.

The ability to chain custom solvers would give people the ability to create incredible simulations.

The big issue is users being able to write custom physics solver nodes themselves. There would need to be an official framework and an easy to follow guide for people to create customs "Fields" physics nodes.