extends CharacterBody2D

var SPEED = 200;
const JUMP = 300;

# physics process function is used when looking into collision detection and using
# the physics engine in Godot! Use this to enable a steasy delta runtime for the collision
# detection part of your game. delta is constant, and code in this method is updated on
# every physic frame.
func _physics_process(delta):
	# Input object opens op for method is_action_pressed to listen for user input.
	if Input.is_action_pressed("ui_left"):
		# the velocity parameter is a reserved parameter for the CharacterBody2d.
		# when a change occurs in the parameter, then the character will move!
		velocity.x = -SPEED;
	elif Input.is_action_pressed("ui_right"):
		velocity.x = SPEED;
	else:
		# velocity zero means the character is at a 'stand still' state. 
		velocity.x = 0;
		
	# the use of is_on_floor function detects, whether character is touching the floor
	# or not. This will allow the character to jump only, when he/she is grounded.
	if Input.is_action_pressed("ui_up") and is_on_floor():
		velocity.y = -JUMP;
		velocity.x = SPEED;
	else: 
		# if the character is not jumping, gravety is doing it's thing, and pulls
		# the character onto the floor.
		velocity.y = velocity.y + SPEED * delta;

	# use this function to set a upwards direction, so the is_on_floor function works!
	# this vector determines the direction of collision detection, an up vector will have
	# the buttom of the character check for collision with the floor...	
	set_up_direction(Vector2.UP)
	# move_and_slide function creates the actual movement of character, when the velocity
	# parameter has been changed. It also do all the collision detection stuff in the background
	# so if the character bumps into a wall, this function will make sure to stop the character.
	move_and_slide()