Godot Platformer Lesson 1a: Player Movement

Summary

This lesson covers player jumps.

Video

Errata

link: https://www.gdquest.com/tutorial/godot/2d/your-first-game/chapter/1-player-and-enemy/

For this video there is a value updated at 1:02:26 that is not mentioned in the video.

Notes

  • In MacOS replace is accessed using command-f

Code

Repository: https://github.com/los-alamos-steam-lab/GDQuest-Platformer/tree/1b-player-jump

Actor Code

extends KinematicBody2D
class_name Actor

const FLOOR_NORMAL = Vector2.UP

export var speed := Vector2(300, 1000)
export var gravity := 4000.0

var _velocity := Vector2.ZERO

Player Code

extends Actor

func _physics_process(delta):
    var is_jump_interrupted: = Input.is_action_just_released("jump") and _velocity.y < 0
    var direction := get_direction()
    _velocity = calculate_move_velocity(_velocity, direction, speed, is_jump_interrupted)
    _velocity = move_and_slide(_velocity, FLOOR_NORMAL)

func get_direction() -> Vector2:
    return Vector2(
        Input.get_action_strength("move_right") - Input.get_action_strength("move_left"),
        -1.0 if Input.is_action_just_pressed("jump") and is_on_floor() else 0.0
    )

func calculate_move_velocity(linear_velocity: Vector2, direction: Vector2, speed: Vector2, is_jump_interrupted: bool) -> Vector2:
    var new_velocity: = linear_velocity
    new_velocity.x = speed.x * direction.x
    new_velocity.y += gravity * get_physics_process_delta_time()
    if direction.y == -1:
        new_velocity.y = speed.y * direction.y
    if is_jump_interrupted:
        new_velocity.y = 0
    return new_velocity

Common Problems

  • Player not jumping when on floor:

    • Sometimes is_on_floor() can be a bit buggy. If you supply a second argument to move_and_slide() then it will know which direction the floor (or rather the ceiling) is. So we want velocity = move_and_slide(velocity, Vector2.UP). This is covered in the video if you are patient, but it can seem like you made a mistake if you’re testing your code as you go.