Orbit

app.rb

@@ -3,21 +3,26 @@ require "gosu"
 load "physobj.rb"
 
 class Window < Gosu::Window
-	attr_accessor :caption, :physobjs
+	attr_accessor :caption, :physobjs, :planets
 	attr_reader :width, :height
 
-	def initialize(title, width, height, physobjs = [])
+	def initialize(title, width, height, physobjs = [], planets = [])
 		super width, height
 		@width, @height = width, height
 		self.caption = "#{title}| #{width}x#{height}"
 
 		@physobjs = physobjs
+		@planets = planets
 	end
 
 	def update
 		@physobjs.each do |obj| 
 			obj.physics 
 		end
+
+		@planets.each do |planet|
+			planet.orbit(@physobjs)
+		end
 	end
 
 	def draw
@@ -26,19 +31,23 @@ class Window < Gosu::Window
 			obj.draw_vector(obj.vel, 10)
 			obj.draw_vector(obj.accel, 500, 0xff_aaffaa)
 		end
+
+		@planets.each do |planet|
+			planet.render
+		end
 	end
 end
 
 
 window = Window.new("Physics!", 1600, 900)
 
-planet = PhysCube.new("Earth", window, 16, 16, 0xff_aaffaa)
+planet = Planet.new("Earth", window, 0xff_aaffaa)
 planet.pos = Vector[800, 450]
 
 cube = PhysCube.new("Cube", window, 8, 8)
-cube.accel = Vector[0, 0.1] 
 cube.vel = Vector[10, 0]
+planet.orbit([cube])
 
-window.physobjs << planet
+window.planets << planet
 window.physobjs << cube
 window.show

physobj.rb

@@ -1,5 +1,6 @@
 require "matrix"
 
+
 class PhysObj
 	attr_accessor :world, :pos, :vel, :accel, :x, :y
 	attr_reader :name
@@ -48,15 +49,14 @@ class PhysCube < PhysObj
 		x_max = world.width - self.width
 		y_max = world.height - self.height
 
-		if( x > x_max ) then 
-			self.pos[0] = x_max 
-			self.vel[0] = 0
-		end
-		if( y > y_max ) then 
-			self.pos[1] = y_max
-			self.vel[1] = 0
-		end
-
+# 		if( x > x_max ) then 
+# 			self.pos[0] = x_max 
+# 			self.vel[0] = 0
+# 		end
+# 		if( y > y_max ) then 
+# 			self.pos[1] = y_max
+# 			self.vel[1] = 0
+# 		end
 	end
 
 	def draw_vector(vec, scale=2, color=0xaf_ffaaaa)
@@ -79,3 +79,25 @@ class PhysCube < PhysObj
 	end
 
 end
+
+
+class Planet < PhysCube
+	attr_reader :gravity
+	def initialize(name, world, color, gravity=0.1)
+		super name, world, gravity*400, gravity*400, color
+
+		@gravity = gravity
+	end
+
+	private def calculate_gravity_vector(obj)
+		dir_vec = self.pos - obj.pos
+		return (self.gravity * dir_vec)/dir_vec.magnitude
+	end
+
+	def orbit(physobjs)
+		physobjs.each do |obj|
+			grav_vec = self.calculate_gravity_vector(obj)
+			obj.accel = grav_vec
+		end
+	end
+end