Godot Lesson 7: Basic Screen Scrolling
=======================================

Summary
--------

This lesson makes the camera follow the player on a grid based map system.  Basically, 
the camera moves with the player as they change rooms, but does not stay centered on the player.
A HUD (heads-up-display) is also added, but not yet implemented.

Prerequisites
--------------

* A player that moves (Lesson 1)
* Everything will make more sense with Lessons 2 through 6

Video
--------

.. raw:: html

   <iframe width="560" height="315" src="https://www.youtube.com/embed/-Rb-FwMQS7w" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>


Resources
-----------

HUD: https://sprites.retro-dragon.com/index.php/2018/08/29/zlg-hud/


Code
--------

Repository: https://github.com/los-alamos-steam-lab/godot-tutorial/tree/7-basic-screen-scrolling


Camera Code
^^^^^^^^^^^^^^^^^^^
  
.. code-block:: gdscript

    extends Camera2D

    var WIDTH = 160
    var HEIGHT = 128

    func _ready():
        # when a body enters or exits, call a function
        $area.connect("body_entered", self, "body_entered")
        $area.connect("body_exited", self, "body_exited")
        
    func _process(delta):
        # Find the position of the player (which means it has to be on the 
        # same level in the scene tree
        var pos = get_node("../player").global_position - Vector2(0, 16)
        
        # use the floor to find the grid position of the player
        # and then multipy to put the camera in the proper spot in the scene
        var x = floor(pos.x/WIDTH) * WIDTH	
        var y = floor(pos.y/HEIGHT) * HEIGHT
        global_position = Vector2(x, y)

    func body_entered(body):
        # make the enemies move when they enter the camera
        if body.get("TYPE") == "ENEMY":
            body.set_physics_process(true)
            
    func body_exited(body):
        # make the enemies stope when they leave the camera
        if body.get("TYPE") == "ENEMY":
            body.set_physics_process(false)