Enable physics interpolation

[Calinou]

Like #130, this enables another new feature in 3.5.

Physics interpolation was disabled on the reactor core's particles as it caused visual glitches (and is not needed there anyway). It was also disabled on the flying forklift as it's actually moved in _process (the engine was printing warnings about it).

To test this, run the demo with the lowest possible settings and see if overall smoothness improves. Note that player/enemy animations are not interpolated (only their movement is), so they remain locked at their 60 Hz rate. In practice, this usually looks good enough. Still, I wonder how these can be interpolated too 🙂

cc @lawnjelly

[lawnjelly]

I might try and take a look at the reactor core when I get a moment, just in case it is a bug on my side.

For animations, isn't there an option to update the animation player bones in process rather than physics_process? 🤔

This should work straight off, there is usually not much saving to interpolate the bones over calculating them fresh each time, and also the hierarchy will be more accurate when calculated using the skeleton each time.

[Calinou]

For animations, isn't there an option to update the animation player bones in process rather than physics_process? thinking

The TPS demo project configures AnimationTree to run in physics process, as movement speed would vary depending on rendering FPS otherwise. This is a bug in root motion (which is used to move the player).