add camera movement

scripts/main_camera.gd

@@ -1,18 +1,40 @@
 extends Camera3D
 
-var mouse_position: Vector2 = Vector2(0, 0)
+const MOVE_SPEED: float = 2
+## How many pixels the mouse needs to be away
+## from the screen edge to move the camera.
+const EDGE_THRESHOLD: float = 10
+
+var mouse_position: Vector2 = Vector2()
 
 func _process(delta: float) -> void:
 	var viewport_size := get_viewport().get_visible_rect().size
 
-	if (mouse_position.x == 0):
-		print('left!')
-	if (mouse_position.x == viewport_size.x - 1):
-		print('right!')
-	if (mouse_position.y == 0):
-		print('top!')
-	if (mouse_position.y == viewport_size.y - 1):
-		print('bottom!')
+	var move_input := Vector2()
+
+	# Horizontal
+	if (mouse_position.x <= EDGE_THRESHOLD):
+		move_input.x = -1
+	elif (mouse_position.x >= viewport_size.x - EDGE_THRESHOLD - 1):
+		move_input.x = 1
+	else:
+		move_input.x = 0
+
+	# Vertical
+	if (mouse_position.y <= EDGE_THRESHOLD):
+		move_input.y = -1
+	elif (mouse_position.y >= viewport_size.y - EDGE_THRESHOLD - 1):
+		move_input.y = 1
+	else:
+		move_input.y = 0
+
+	var direction := (
+			Vector3(move_input.x, 0, move_input.y)
+			.rotated(Vector3.UP, rotation.y)
+	)
+
+	var velocity := direction * MOVE_SPEED
+	position += velocity * delta
 
 func _input(event: InputEvent) -> void:
 	if event is InputEventMouseMotion: