Implement wall boosts

When a liner is going forward along a wall, it is going faster. It's
a cumulative bonus : if it is running with a wall on both sides, the
speed bonus is doubled.

godot/Scripts/CharTween.gd

@@ -1,24 +1,49 @@
 extends Tween
 # Drive moves for player
 
+const MINIMAL_DURATION = 0.01
+
 export var default_duration = 0.1
 export var drift_duration = 0.2
+export var boost_bonus = 0.02
 
 var current_duration = default_duration
+var current_bonus = 0.0
 
 
 func connect_into(o):
 	connect("tween_completed", o, "_on_tween_completed")
 
 
-func move_char(c, target, duration = current_duration):
+func move_char(character, target):
+	move_char_during(character, target, get_computed_duration())
+
+
+func move_char_during(c, target, duration):
 	interpolate_property(c, "position", c.get_position(), target, duration, Tween.TRANS_LINEAR, Tween.EASE_OUT_IN)
 
 
-func rotate_char(c, from, to, duration = current_duration):
+func rotate_char(character, from, to):
+	rotate_char_during(character, from, to, get_computed_duration())
+
+
+func rotate_char_during(c, from, to, duration):
 	interpolate_property(c, "rotation_degrees", from, to, duration, Tween.TRANS_LINEAR, Tween.EASE_OUT)
 
 
+func set_boost(value:int):
+	current_bonus = boost_bonus * value
+
+
+func get_computed_duration():
+	var duration = current_duration - current_bonus
+
+	if duration < MINIMAL_DURATION :
+		return MINIMAL_DURATION
+
+	return duration
+
+
 func _on_Player_drift_started():
 	current_duration = drift_duration
 

godot/Scripts/Player.gd

@@ -103,8 +103,8 @@ func spawn(newGrid, newPosition, newOrientation):
 	apply_turn()
 
 	# Animate spawning
-	tween.rotate_char(self, rotation_degrees, newOrientation, LEVEL_SPAWN_DURATION)
-	tween.move_char(self, newPosition, LEVEL_SPAWN_DURATION)
+	tween.rotate_char_during(self, rotation_degrees, newOrientation, LEVEL_SPAWN_DURATION)
+	tween.move_char_during(self, newPosition, LEVEL_SPAWN_DURATION)
 	tween.start()
 
 
@@ -172,6 +172,20 @@ func end_drift():
 		emit_signal("drift_ended")
 
 
+func apply_wall_boost():
+	var n := 0
+	if has_block_on(Side.LEFT):
+		n += 1
+	if has_block_on(Side.RIGHT):
+		n += 1
+
+	tween.set_boost(n)
+
+
+func end_wall_boost():
+	tween.set_boost(0)
+
+
 func move():
 	if !running:
 		return
@@ -184,8 +198,10 @@ func move():
 			apply_turn()
 		else:
 			apply_drift()
+		end_wall_boost()
 	else:
 		end_drift()
+		apply_wall_boost()
 
 	go_forward()
 
@@ -211,7 +227,8 @@ func stop():
 	if running:
 		remove_from_group("running")
 		generate_wall()
-	running = false
+		end_wall_boost()
+		running = false
 
 
 func run():
@@ -224,5 +241,10 @@ func run():
 func is_running():
 	return running
 
+
+func is_linear():
+	return dire_delta == 0
+
+
 func is_transversal():
-	return dire_delta != 0
+	return !is_linear()