is_on_floor() doesn't work with _process(delta) and high FPS on trimesh collision

[JupiterRider]

Godot version:
3.2 Stable

OS/device including version:
Linux 5.5.2-arch1-1

Issue description:
If you use is_on_floor() and the kinematic body is on a on an uneven trimesh collision, is_on_floor() returns false, if you call move_and_slide() with _process(delta) AND you have high FPS.

Steps to reproduce:

1. Create a uneven mesh.

2. Give the mesh a trimesh collision.

3. Place a Kinematic body

4. Attach a script to the Kinematic body

5. Use _process(delta) instead of _physics_process(delta)

6. Disable VSYNC to make sure having high FPS

Minimal reproduction project:
https://github.com/JupiterRider/is_on_floor_issue

[KoBeWi]

Well, it's rather expected that you need to use physics methods inside physics_process(delta).

[jamie-pate]

Probably related? #35780

[Seel]

Well, it's rather expected that you need to use physics methods inside physics_process(delta).

I use _process for the player because the camera scrolling and player movement is smoother when moving at 100+ fps. :/

However the minimal reproduction project has me standing on_floor when standing still and only lifting off the ground when moving.

[Calinou]

I use _process for the player because the camera scrolling and player movement is smoother when moving at 100+ fps. :/

It's probably a better idea to use _physics_process() or _integrate_forces() with lawnjelly's smoothing-addon for physics interpolation. This prevents physics from behaving differently in subtle ways depending on the rendering FPS (this will happen even if you use delta consistently).

[KoBeWi]

Closing, only do physic things in physics_process, otherwise the behavior is undefined (it might work or it might break).