Make ShootyEnemy cycle between targets by velocity

ShootyEnemy.gd

@@ -1,5 +1,8 @@
 extends KinematicBody
 
+# An enemy which shoots at the future player position and moves between two targets within a given
+# amount of time.
+
 
 export(NodePath) var player_node
 onready var player = get_node(player_node)
@@ -7,46 +10,83 @@ onready var player = get_node(player_node)
 export(NodePath) var solar_system_node
 onready var solar_system = get_node(solar_system_node)
 
+export(Array, NodePath) var target_paths
+
+export var target_fly_time := 5.0
+var time_passed_since_fly_start := 0.0
+var current_target_index = 0
+
 var bullet_scene = preload("res://Bullet.tscn")
 var bullet_velocity = 40.0
 
-var target
-var velocity := Vector3(0.0, 1.0, 1.0)
+var shoot_target
+var velocity := Vector3.ZERO
 
 
 func _ready():
+	# Shoot everytime the timer times out
 	$ShotTimer.connect("timeout", self, "shoot_bullet")
 	
+	# Set up pathing: Start at the first target
+	global_transform.origin = get_node(target_paths[0]).global_transform.origin
+	_set_velocity_to_fly_towards_next_target()
+
+
+# Picks the next target position from the `target_paths` list and set the `velocity` appropriately
+# so that the target will be reached after `target_fly_time`.
+func _set_velocity_to_fly_towards_next_target():
+	current_target_index = (current_target_index + 1) % target_paths.size()
+	
+	# Vector from here to the new target
+	var vector_to_next = (get_node(target_paths[current_target_index]).global_transform.origin
+			- global_transform.origin)
+	
+	# s = v * t --> v = s / t
+	velocity = vector_to_next / target_fly_time
+	time_passed_since_fly_start = 0.0
+
 
 func _physics_process(delta):
 	# Project the player's position into the future
-	target = _get_future_position(
+	shoot_target = _get_future_position(
 		player.get_center(),
 		player.velocity - velocity
 	)
 	
-	if target:
+	# Look at the target that will be shot at, with the gravity as the down vector
+	if shoot_target:
 		var gravity = solar_system.get_gravity_acceleration(global_transform.origin)
-		look_at(target, gravity)
+		look_at(shoot_target, gravity)
 	
+	# Have we rearched the target?
+	time_passed_since_fly_start += delta
+	if time_passed_since_fly_start >= target_fly_time:
+		# If so, fly towards the next target
+		_set_velocity_to_fly_towards_next_target()
+	
+	# Apply velocity
 	global_transform.origin += velocity * delta
 
 
 func shoot_bullet():
-	if not target:
+	if not shoot_target:
 		# Player can't be hit right now, abort
 		return
 	
+	# Add a bullet
 	var instance = bullet_scene.instance()
 	get_tree().get_root().add_child(instance)
 	
+	# Make the bullet start at the current position of this object and fly towards the target.
+	# The own velocity is added because of galilean relativity.
 	instance.global_transform.origin = global_transform.origin - global_transform.basis.z
-	instance.velocity = velocity + (target - global_transform.origin).normalized() * bullet_velocity
+	instance.velocity = velocity + (shoot_target - global_transform.origin).normalized() * bullet_velocity
 
 
+# Return the position at which a bullet fired forwards and with the velocity `bullet_velocity` would
+# intersect with the object that is at `position` and moving with the given `velocity`
 func _get_future_position(position, velocity):
 	# Solution to the quadratic formula gives us the time at which the player would be hit
-	# TODO: Take acceleration into account as well!
 	var a = pow(velocity.x, 2) + pow(velocity.y, 2) + pow(velocity.z, 2) - pow(bullet_velocity, 2)
 	var b = 2 * (velocity.x * (position.x - global_transform.origin.x)
 		+ velocity.y * (position.y - global_transform.origin.y)
@@ -67,4 +107,5 @@ func _get_future_position(position, velocity):
 	var t = min(t1, t2)
 	if t < 0: t = max(t1, t2)
 	
+	# Return the position given by the time we calculated
 	return position + t * velocity

World.tscn

@@ -190,10 +190,17 @@ environment = SubResource( 11 )
 transform = Transform( 0.866025, -0.353553, 0.353553, 0, 0.707107, 0.707107, -0.5, -0.612372, 0.612372, 0, 10, 0 )
 shadow_enabled = true
 
+[node name="EnemyPos1" type="Position3D" parent="."]
+transform = Transform( 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 8, 20 )
+
+[node name="EnemyPos2" type="Position3D" parent="."]
+transform = Transform( 1, 0, 0, 0, 1, 0, 0, 0, 1, -46.5073, 54.1815, 76.6368 )
+
 [node name="ShootyEnemy" parent="." instance=ExtResource( 6 )]
 transform = Transform( 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 8, 20 )
 player_node = NodePath("../Player")
 solar_system_node = NodePath("../Planets")
+target_paths = [ NodePath("../EnemyPos1"), NodePath("../EnemyPos2") ]
 
 [node name="Player" parent="." instance=ExtResource( 1 )]
 transform = Transform( 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 3, 0 )