My RigidBody2D is not being affected by linear damping

Question

Hi! I'm new to physics based gameplay and am currently trying to figure out how to properly move RigidBody2D object. My code:

extends RigidBody2D

export var thrust_power := 100.0
export var movement_power := 100.0

var thrust_status := 0.0
var horizontal_direction := 0.0


func _process(delta: float) -> void:
    horizontal_direction = Input.get_action_strength("right") - Input.get_action_strength("left")


func _integrate_forces(state: Physics2DDirectBodyState) -> void:
    # Vertical force
    if Input.is_action_pressed("thrust"):
        add_central_force(thrust_power * Vector2.UP)
    # Horizontal force
    add_central_force(movement_power * horizontal_direction * Vector2.RIGHT)

At first, my object is properly being affected by gravity. When I hold "thrust" key and accumulate enough force, my object starts to move upward but does that infinitely and won't be affected by gravity again even though I don't hold the "thrust" key anymore (the code should be adding 0 force).
Currently my linear damping in the project settings is of default value 0.1 and is not overriden on the rigidbody itself.
It's very confusing and I couldn't find anything in the docs or anywhere else. Thanks!

Answer 1

Ok, everybody else ignored this one so I'll have a crack at it. (you drew the short straw and got me, sorry!)

First obvious blunder: you're calling the Input class in _process and not _physics_process - big red flag there. The former is just every frame, the latter is linked to the physics engine (with a set max framerate) which is obviously what you want given that you're working with the engine.

Don't call the physics engine twice in one frame. It's like a new girlfriend in that regard, it doesn't go down well to text twice before she's repled. Like this:

extends RigidBody2D

var power = 1000.0
var force = Vector2.ZERO

func _physics_process(delta):
  force.x += Input.get_action_strength("right")\ 
            -Input.get_action_strength("left") * power * delta
  force.y = if Input.is_action_pressed("thrust"):
      force.y += power * delta

func _integrate_forces(state):
    add_central_force(force)

Obviously, I've tested nothing aside from this fine glass of red.

ps. you probably want an is_on_floor for jumping but I'll leave that to you.
pps. don't you want gravity?

Comments

Hey, thanks for your answer. I think it is perfectly save to get Input in the process function as it is not related to physics. But I will try to call the addcentral_force only once, just to be sure.