From c4ae3b0ee4bd338995cfecf34e0aeb49f05fa70e Mon Sep 17 00:00:00 2001
From: Joris Guyonvarch
Date: Tue, 2 Sep 2014 21:35:58 +0200
Subject: Initial commit

---
 src/Physics.elm | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 src/Physics.elm

(limited to 'src/Physics.elm')

diff --git a/src/Physics.elm b/src/Physics.elm
new file mode 100644
index 0000000..b59b3e1
--- /dev/null
+++ b/src/Physics.elm
@@ -0,0 +1,33 @@
+module Physics where
+
+import Vec2 (..)
+
+getNewPosAndSpeed : Float -> Vec2 -> (Float -> Float) -> (Vec2, Vec2) -> (Vec2, Vec2)
+getNewPosAndSpeed dt dir computeSpeed (pos, speed) =
+  let move = getMove (computeSpeed dt) dir
+      acc = getAcc move speed
+      newPos = getNewPos dt acc speed pos
+      newSpeed = getNewSpeed dt acc speed
+  in  ( newPos
+      , newSpeed
+      )
+
+getMove : Float -> Vec2 -> Vec2
+getMove speed dir =
+  if (isNull dir)
+    then {x = 0, y = 0}
+    else
+      let angle = atan2 dir.y dir.x
+      in  { x = speed * cos angle
+          , y = speed * sin angle
+          }
+
+getAcc : Vec2 -> Vec2 -> Vec2
+getAcc move speed = (move `div` 800) `sub` (speed `div` 1000)
+
+getNewPos : Float -> Vec2 -> Vec2 -> Vec2 -> Vec2
+getNewPos dt acc speed pos =
+  ((dt^2 / 2) `mul` acc) `add` ((dt `mul` speed) `add` pos)
+
+getNewSpeed : Float -> Vec2 -> Vec2 -> Vec2
+getNewSpeed dt acc speed = add (mul dt acc) speed
-- 
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