Color visualization for grounded character controller

[ThierryBerger]

It's currently difficult to assess if character controller ground detection works correctly, this adds a visual helper (the capsule turns red when not grounded) to detect it more quickly in the examples.

character_controller_color.mp4

ground detection analysis

when calling colliders_with_aabb_intersecting_aabb from within detect_grounded_status_and_apply_friction
, it sometimes doesn't get any manifests, resulting in grounded = false.

• Honestly, a raycast down is probably less work than fiddling with nudge factor, numerical errors, shape implementations and whatnot 🤔

• Or maybe just exposing or bumping up the predict ground distance around

  rapier/src/control/character_controller.rs

  Line 400 in 661c33f

  self.offset.eval(up_extends) * 1.1

• I tested it against should allow grounding with no movement counter to the up direction #481, and still have not grounded frames.

[sebcrozet]

Good point, thanks!