Add shooting enemy which shoots at future player pos

Works fairly well, although it doesn't account for changing acceleration which happens due to the changing gravity. I guess this is good enough, since it does hit if the player isn't careful

Bullet.gd

@@ -0,0 +1,28 @@
+extends Spatial
+
+
+var target := Vector3.ZERO
+
+var acceleration := Vector3.ZERO
+var velocity := Vector3.ZERO
+
+export var acceleration_factor = 5.0
+export var accelerating := false
+
+
+func _ready():
+	$HitArea.connect("body_entered", self, "_on_hit_body")
+
+
+func _on_hit_body(body):
+	if body.name == "Player":
+		print("Player hit!")
+
+
+func _process(delta):
+	if accelerating:
+		var direction = (target - global_transform.origin).normalized()
+		acceleration += direction * acceleration_factor * delta
+		velocity += acceleration
+	
+	global_transform.origin += velocity * delta

InputConverter.gd

@@ -33,5 +33,3 @@ func _process(delta):
 	# Limit at length 1
 	if input.length() > 1.0:
 		input /= input.length()
-	
-	print(input)

MovingPlatform.gd

@@ -30,8 +30,6 @@ func _process(delta):
 	
 	velocity = (translation - translation_before) / delta
 	
-	print(velocity)
-	
 	# Rotate according to gravity
 	var gravity_acceleration = get_node(solar_system).get_gravitation_acceleration(global_transform.origin)
 	

Planets.gd

@@ -10,7 +10,7 @@ const distance_multiplier = 318550   # thus, a radius of 20 results in an earth-
 
 # If the gravity doesn't feel like it should, this scales it. A higher value means that the pull is
 # stronger.
-const gravity_multiplier = 5.0
+const gravity_multiplier = 10.0
 
 
 func get_gravitation_acceleration(position: Vector3) -> Vector3:

Player.gd

@@ -32,6 +32,10 @@ func _input(event):
 		jumping = false
 
 
+func get_center():
+	return global_transform.origin + global_transform.basis.y
+
+
 func apply_acceleration(acceleration):
 	# First drag, then add the new acceleration
 	# For drag: Lerp towards the target velocity

ShootyEnemy.gd

@@ -0,0 +1,66 @@
+extends KinematicBody
+
+
+export(NodePath) var player_node
+onready var player = get_node(player_node)
+
+export(NodePath) var solar_system_node
+onready var solar_system = get_node(solar_system_node)
+
+var bullet_scene = preload("res://Bullet.tscn")
+var bullet_velocity = 40.0
+
+var target
+
+
+func _ready():
+	$ShotTimer.connect("timeout", self, "shoot_bullet")
+
+
+func _process(delta):
+	# Project the player's position into the future
+	target = _get_future_position(
+		player.get_center(),
+		player.velocity
+	)
+	
+	if target:
+		var gravity = solar_system.get_gravitation_acceleration(global_transform.origin)
+		look_at(target, gravity)
+
+
+func shoot_bullet():
+	if not target:
+		# Player can't be hit right now, abort
+		return
+	
+	var instance = bullet_scene.instance()
+	get_tree().get_root().add_child(instance)
+	
+	instance.global_transform.origin = global_transform.origin
+	instance.velocity = (target - global_transform.origin).normalized() * bullet_velocity
+
+
+func _get_future_position(position, velocity):
+	# Solution to the quadratic formula gives us the time at which the player would be hit
+	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)
+		+ velocity.z * (position.z - global_transform.origin.z))
+	
+	var c = pow(position.x - global_transform.origin.x, 2.0) \
+		+ pow(position.y - global_transform.origin.y, 2.0) \
+		+ pow(position.z - global_transform.origin.z, 2.0)
+	
+	var discriminant = pow(b, 2) - 4 * a * c
+	
+	if (discriminant < 0): return null # Can't hit the target :(
+	
+	var t1 = (-b + sqrt(discriminant)) / (2 * a)
+	var t2 = (-b - sqrt(discriminant)) / (2 * a)
+	
+	# Choose the smallest positive t value
+	var t = min(t1, t2)
+	if t < 0: t = max(t1, t2)
+	
+	return position + t * velocity

ShootyEnemy.tscn

@@ -0,0 +1,24 @@
+[gd_scene load_steps=4 format=2]
+
+[ext_resource path="res://ShootyEnemy.gd" type="Script" id=1]
+
+[sub_resource type="PrismMesh" id=1]
+
+[sub_resource type="ConcavePolygonShape" id=2]
+data = PoolVector3Array( 0, 1, 1, 1, -1, 1, -1, -1, 1, 0, 1, -1, -1, -1, -1, 1, -1, -1, 0, 1, 1, 0, 1, -1, 1, -1, 1, 0, 1, -1, 1, -1, -1, 1, -1, 1, 0, 1, -1, 0, 1, 1, -1, -1, -1, 0, 1, 1, -1, -1, 1, -1, -1, -1, -1, -1, 1, 1, -1, 1, -1, -1, -1, 1, -1, 1, 1, -1, -1, -1, -1, -1 )
+
+[node name="ShootyEnemy" type="KinematicBody"]
+script = ExtResource( 1 )
+
+[node name="MeshInstance" type="MeshInstance" parent="."]
+transform = Transform( 1, 0, 0, 0, -4.37114e-08, 1, 0, -1, -4.37114e-08, 0, 0, 0 )
+mesh = SubResource( 1 )
+material/0 = null
+
+[node name="CollisionShape" type="CollisionShape" parent="."]
+transform = Transform( 1, 0, 0, 0, -4.37114e-08, 1, 0, -1, -4.37114e-08, 0, 0, 0 )
+shape = SubResource( 2 )
+
+[node name="ShotTimer" type="Timer" parent="."]
+process_mode = 0
+autostart = true

World.tscn

@@ -1,10 +1,11 @@
-[gd_scene load_steps=18 format=2]
+[gd_scene load_steps=19 format=2]
 
 [ext_resource path="res://Player.gd" type="Script" id=1]
 [ext_resource path="res://Planets.gd" type="Script" id=2]
 [ext_resource path="res://Planet.gd" type="Script" id=3]
 [ext_resource path="res://PlanetMaterial.tres" type="Material" id=4]
 [ext_resource path="res://MovingPlatform.gd" type="Script" id=5]
+[ext_resource path="res://ShootyEnemy.tscn" type="PackedScene" id=6]
 
 [sub_resource type="CubeMesh" id=1]
 size = Vector3( 4, 0.5, 4 )
@@ -106,13 +107,14 @@ glow_bloom = 0.1
 [node name="World" type="Spatial"]
 
 [node name="MovingPlatformPivot" type="Position3D" parent="."]
-transform = Transform( 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, -20, 0 )
+transform = Transform( 1, 0, 0, 0, 1, 0, 0, 0, 1, -125, 37, 60 )
 
 [node name="MovingPlatform" type="KinematicBody" parent="MovingPlatformPivot" groups=[
 "MovingPlatform",
 ]]
-transform = Transform( 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 30, 0 )
+transform = Transform( 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 60, 0 )
 script = ExtResource( 5 )
+move_speed = 5.0
 solar_system = NodePath("../../Planets")
 
 [node name="MeshInstance" type="MeshInstance" parent="MovingPlatformPivot/MovingPlatform"]
@@ -139,16 +141,28 @@ material/0 = null
 [node name="CollisionShape" type="CollisionShape" parent="Planets/Earth"]
 shape = SubResource( 7 )
 
-[node name="StaticBody" type="StaticBody" parent="Planets"]
+[node name="Mars" type="StaticBody" parent="Planets"]
 transform = Transform( 1, 0, 0, 0, 1, 0, 0, 0, 1, -20, 37, 30 )
 script = ExtResource( 3 )
 mass = 5.0
 
-[node name="MeshInstance" type="MeshInstance" parent="Planets/StaticBody"]
+[node name="MeshInstance" type="MeshInstance" parent="Planets/Mars"]
 mesh = SubResource( 8 )
 material/0 = ExtResource( 4 )
 
-[node name="CollisionShape" type="CollisionShape" parent="Planets/StaticBody"]
+[node name="CollisionShape" type="CollisionShape" parent="Planets/Mars"]
+shape = SubResource( 9 )
+
+[node name="Jupiter" type="StaticBody" parent="Planets"]
+transform = Transform( 3, 0, 0, 0, 3, 0, 0, 0, 3, -125, 37, 60 )
+script = ExtResource( 3 )
+mass = 40.0
+
+[node name="MeshInstance" type="MeshInstance" parent="Planets/Jupiter"]
+mesh = SubResource( 8 )
+material/0 = ExtResource( 4 )
+
+[node name="CollisionShape" type="CollisionShape" parent="Planets/Jupiter"]
 shape = SubResource( 9 )
 
 [node name="Player" type="KinematicBody" parent="."]
@@ -176,3 +190,8 @@ environment = SubResource( 12 )
 [node name="DirectionalLight" type="DirectionalLight" parent="WorldEnvironment"]
 transform = Transform( 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 10, 0 )
 shadow_enabled = true
+
+[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")