From 716ce85464ee6d57a424a00d2535b3c2ce6ad9cb Mon Sep 17 00:00:00 2001
From: Joris Guyonvarch
Date: Thu, 5 Mar 2015 22:55:06 +0100
Subject: Adding a wave move

---
 src/CloudStep.elm | 4 ++--
 src/Physics.elm   | 9 +++++++++
 src/Vec2.elm      | 9 +++++++++
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/CloudStep.elm b/src/CloudStep.elm
index 033c3c5..e6bfc96 100644
--- a/src/CloudStep.elm
+++ b/src/CloudStep.elm
@@ -8,7 +8,7 @@ import Geometry (..)
 import Player (..)
 import Board (boardSize, boardDiagonal)
 import Point (..)
-import Physics (getMove)
+import Physics (getMove, getWaveMove)
 import Cloud (..)
 import Config (..)
 
@@ -61,7 +61,7 @@ getNewPoint time seed =
         , initDest = initDest
         , move initTime initPos initDest time =
             let delta = time - initTime
-                move = getMove (pointSpeed delta) (initDest `sub` initPos)
+                move = getWaveMove (pointSpeed delta) (initDest `sub` initPos) 10 10
             in  initPos `add` move
         }
       , seed''
diff --git a/src/Physics.elm b/src/Physics.elm
index 2d2d627..c68ab58 100644
--- a/src/Physics.elm
+++ b/src/Physics.elm
@@ -22,6 +22,15 @@ getMove speed dir =
           , y = speed * sin angle
           }
 
+getWaveMove : Float -> Vec2 -> Float -> Float -> Vec2
+getWaveMove speed dir amplitude period =
+  let move = getMove speed dir
+      perpendMove =
+        getMove
+          (amplitude * (sin ((norm move) / period)))
+          (clockwiseRotate90 move)
+  in  move `add` perpendMove
+
 getAcc : Vec2 -> Vec2 -> Vec2
 getAcc move speed = (move `div` 300) `sub` (speed `div` 300)
 
diff --git a/src/Vec2.elm b/src/Vec2.elm
index 056c657..c980e1a 100644
--- a/src/Vec2.elm
+++ b/src/Vec2.elm
@@ -29,6 +29,15 @@ div v d =
   , y = v.y / d
   }
 
+norm : Vec2 -> Float
+norm v = sqrt(v.x ^ 2 + v.y ^ 2)
+
+clockwiseRotate90 : Vec2 -> Vec2
+clockwiseRotate90 v =
+  { x = -v.y
+  , y = v.x
+  }
+
 isNull : Vec2 -> Bool
 isNull v = (v.x == 0) && (v.y == 0)
 
-- 
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