Movement State Implementation

Question

I'm making an RPG where the player can freely move around the over world with the WASD keys; but when in combat the player switches to a tactical grid-based movement controlled by the mouse. I thought to use states to accomplish this; but I don't know how to properly do this.

Here is my code for my movement mechanics:

extends KinematicBody2D

export (int) var speed = 250
var velocity

var states = {movement:[Over_Mov, Tile_Mov]}
var current_state = null

func _ready():
    current_state = Over_Mov

func get_input():
    velocity = Vector2()

    if Input.is_action_pressed("ui_up"):
        velocity.y -= 1
    elif Input.is_action_pressed("ui_down"):
        velocity.y += 1
    elif Input.is_action_pressed("ui_right"):
        velocity.x += 1
    elif Input.is_action_pressed("ui_left"):
        velocity.x -= 1
    velocity = velocity.normalized() * speed

func _physics_process(delta):
    get_input()
    move_and_collide(velocity*delta)

I am using Godot's sample for movement mechanics.

Answer 1

One simple way to handle state is to use an enum with match.

enum State { OVER_MOV, TILE_MOV }

export(int) var speed = 250
var velocity
var current_state = OVER_MOV

func handle_over_mov_input():
    velocity = Vector2()
    if Input.is_action_pressed("ui_up"):
        velocity.y -= 1
    elif Input.is_action_pressed("ui_down"):
        velocity.y += 1
    elif Input.is_action_pressed("ui_right"):
        velocity.x += 1
    elif Input.is_action_pressed("ui_left"):
        velocity.x -= 1
    velocity = velocity.normalized() * speed

func handle_tile_mov_input():
    # .. handle tile mov input here
    pass

func _physics_process(delta):
    match current_state:
        OVER_MOV: handle_over_mov_input()
        TILE_MOV: handle_tile_mov_input()
    move_and_collide(velocity*delta)
    if some_state_changing_condition:
        current_state = other_state

If you would like to get more involved with the state pattern take a look at the State chapter from the GameProgrammingPatterns book.