Prevent free movement troll from leaving tile area

Move troll's root pivot to line up with their collider. This makes their
global_position a good representation of where they are.

Add check for moving to an invalid tile and undo our move. In my tests,
this isn't less smooth than skipping the move_and_slide if
(global_position + velocity * dt) is an invalid tile and allows sliding
to resolve us to a slightly different position.

Author: idbrii

2d/hexagonal_map/map.tscn

@@ -24,9 +24,10 @@ script = ExtResource("3_urblq")
 position = Vector2(-174, 28)
 grid = NodePath("../../Tiles/Layer0")
 
-[node name="FreeMovementTroll" parent="TrollSpawner" instance=ExtResource("2")]
+[node name="FreeMovementTroll" parent="TrollSpawner" node_paths=PackedStringArray("grid") instance=ExtResource("2")]
 modulate = Color(1.5, 1.5, 1.5, 1)
 position = Vector2(3.81897, -137.288)
+grid = NodePath("../../Tiles/Layer0")
 
 [node name="CanvasLayer" type="CanvasLayer" parent="."]
 

2d/hexagonal_map/troll_free.gd

@@ -1,15 +1,20 @@
 extends CharacterBody2D
 
-const MOTION_SPEED = 30
-const FRICTION_FACTOR = 0.89
-const TAN30DEG = tan(deg_to_rad(30))
+const MOTION_SPEED: float = 30.0
+const FRICTION_FACTOR: float = 0.89
+const TAN30DEG: float = tan(deg_to_rad(30.0))
+
+
+@export var grid: TileMapLayer
 
 
 func become_active_troll() -> void:
 	pass
 
 
 func _physics_process(_delta: float) -> void:
+	var prev_position: Vector2 = global_position
+
 	var motion := Vector2()
 	motion.x = Input.get_axis(&"move_left", &"move_right")
 	motion.y = Input.get_axis(&"move_up", &"move_down")
@@ -19,3 +24,12 @@ func _physics_process(_delta: float) -> void:
 	# Apply friction.
 	velocity *= FRICTION_FACTOR
 	move_and_slide()
+
+
+	# Prevent movement off of the grid tiles. Alternatively, you could add a
+	# border tile around the outside of your world with physics enabled in the
+	# TileMapLayer. That would allow nice sliding along the walls of the world.
+	var dest_tile: int = grid.get_world_tile(global_position)
+	var has_tile: bool = dest_tile >= 0
+	if not has_tile:
+		global_position = prev_position

2d/hexagonal_map/troll_free.tscn

@@ -10,19 +10,21 @@ radius = 16.0
 script = ExtResource("1")
 
 [node name="Sprite2D" type="Sprite2D" parent="."]
+position = Vector2(-3.74084, -19.5)
 texture = ExtResource("2")
 
 [node name="Shadow" type="Sprite2D" parent="."]
 modulate = Color(0, 0, 0, 0.501961)
 show_behind_parent = true
-position = Vector2(16.4422, 4.89438)
+position = Vector2(12.7014, -14.6056)
 scale = Vector2(0.794259, 1.04505)
 skew = 0.523599
 texture = ExtResource("2")
 
 [node name="CollisionShape2D" type="CollisionShape2D" parent="."]
-position = Vector2(3.24216, 19.453)
+position = Vector2(-0.498685, -0.0470009)
 shape = SubResource("1")
 
 [node name="Camera2D" type="Camera2D" parent="."]
+position = Vector2(-3.74084, -19.5)
 process_callback = 0