gravity implemennted

body.lua

@@ -0,0 +1,60 @@
+BodyList = {}
+Body = class(nil,{type=0})
+
+function newBody(x,y,mass,color)
+  local o = {}
+  -- coordinates
+  o.x = x
+  o.y = y
+  -- velocities
+  o.vx = 0
+  o.vy = 0
+  -- accceleration
+  o.ax = 0
+  o.ay = 0
+  -- mass
+  o.mass = mass
+  -- color
+  o.color = color
+	table.insert(BodyList,o)
+end
+
+function UpdateBodiesAcceleration()
+  for n, body in pairs(BodyList) do
+    local ax = 0
+    local ay = 0
+    for o_n, other_body in pairs(BodyList) do
+      if n ~= o_n then
+
+        local dx = other_body.x - body.x
+        local dy = other_body.y - body.y
+
+        local d2 = dx*dx + dy*dy
+
+        local f =
+          (CONST_G * other_body.mass) /
+          d2 * math.sqrt(d2 + CONST_S)
+
+        ax = ax + dx * f
+        ay = ay + dy * f
+      end
+    end
+
+    body.ax = ax
+    body.ay = ay
+  end
+end
+
+function UpdateBodiesVelocity(dt)
+  for _, body in pairs(BodyList) do
+    body.vx = body.vx + body.ax * dt
+    body.vy = body.vy + body.ay * dt
+  end
+end
+
+function UpdateBodiesPosition(dt)
+  for _, body in pairs(BodyList) do
+    body.x = body.x + body.vx * dt
+    body.y = body.y + body.vy * dt
+  end
+end