Fix 3D moving platform logic

Same thing that was already done in 2D, applies moving platform motion
by using a call to move_and_collide that excludes the platform itself,
instead of making it part of the body motion.

Helps with handling walls and slopes correctly when the character walks
on the moving platform.

Also made some minor adjustments to the 2D version and documentation.

Co-authored-by: fabriceci <fabricecipolla@gmail.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/scene/2d/physics_body_2d.cpp b/scene/2d/physics_body_2d.cpp
index 00eeb60192..9235a2290e 100644
--- a/scene/2d/physics_body_2d.cpp
+++ b/scene/2d/physics_body_2d.cpp
@@ -1075,7 +1075,7 @@ void CharacterBody2D::move_and_slide() {
 	floor_normal = Vector2();
 	floor_velocity = Vector2();
 
-	if (current_floor_velocity != Vector2()) {
+	if (current_floor_velocity != Vector2() && on_floor_body.is_valid()) {
 		PhysicsServer2D::MotionResult floor_result;
 		Set<RID> exclude;
 		exclude.insert(on_floor_body);