Make gravity variable, add procedural planet texture

Planet.gd

@@ -0,0 +1,4 @@
+extends StaticBody
+
+
+export(float) var mass

Planets.gd

@@ -1,7 +1,29 @@
 extends Spatial
 class_name SolarSystem
 
+const G = 6.674 * pow(10, -11)
+
+# Because we're dealing with a miniature, we want small masses and distances to have noticeable
+# gravitational effects. These multipliers adapt the scale of the game to an earth-like scale.
+const mass_multiplier = pow(10, 24)  # thus, the earth would get a mass of 6
+const distance_multiplier = 318550   # thus, a radius of 20 results in an earth-like radius
+
+# If the gravity doesn't feel like it should, this scales it. A higher value means that the pull is
+# stronger.
+const gravity_multiplier = 2.5
+
 
 func get_gravitation_acceleration(position: Vector3) -> Vector3:
 	# TODO: Take all planets and their mass into account
-	return ($Earth.transform.origin - position).normalized()
+	var pos_to_center = ($Earth.transform.origin - position)
+	var distance = pos_to_center.length()
+	
+	var force = _gravity($Earth.mass * mass_multiplier, distance * distance_multiplier)
+	force *= gravity_multiplier
+	
+	return (pos_to_center / distance) * force
+
+
+# Formula for gravity
+static func _gravity(mass, distance):
+	return (G * mass) / (distance * distance)

Player.gd

@@ -4,8 +4,9 @@ extends KinematicBody
 var acceleration := Vector3(0.0, -9.81, 0.0)
 var velocity := Vector3(0.0, 0.0, 0.0)
 
-var move_speed = 5.0
+var move_speed = 15.0
-var jump_accel = 300.0
+var jump_accel = 600.0
+var rotate_speed = 2.0
 
 export(NodePath) var solar_system
 
@@ -26,20 +27,21 @@ func _physics_process(delta):
 	if Input.is_action_pressed("ui_down"):
 		move_velocity.z += move_speed
 	if Input.is_action_pressed("ui_left"):
-		rotate(transform.basis.y, delta)
+		rotate(transform.basis.y, delta * rotate_speed)
 	if Input.is_action_pressed("ui_right"):
-		rotate(transform.basis.y, -delta)
+		rotate(transform.basis.y, -delta * rotate_speed)
 	
 	# Make movement local
 	move_velocity = transform.basis * move_velocity
 	
-	# Jumping
+	# Jumping and Gravity
+	var gravity_acceleration = get_node(solar_system).get_gravitation_acceleration(transform.origin)
+	
 	if Input.is_action_just_pressed("ui_select"):
-		move_acceleration.y += jump_accel
+		move_acceleration += gravity_acceleration.normalized() * jump_accel
 	
 	# Gravity
-	var gravity_acceleration = get_node(solar_system).get_gravitation_acceleration(transform.origin)
+	velocity += (gravity_acceleration - move_acceleration) * delta
-	velocity += (gravity_acceleration * 9.81 - gravity_acceleration * move_acceleration.y) * delta
 	var movement = (move_velocity + velocity) * delta
 	
 	# Apply movement to position