hmm, what I gather from that is he might not have needed to rewrite everything , for example the physics, he might have just used add offset and other things to avoid messing with physics engine.
Not to mention once you make PhysX use double precision you’ll likely see a huge drop in GPU acceleration for physX because the ratio of performance of GPU in single precision to double precision is nearly 24:1 , so at that point you might have to switch to CPU physics.
Nevertheless I’ve sent him a PM asking some basic question before I drive down this road