1 files changed, 19 insertions, 5 deletions
diff --git a/src/Utils/Physics.elm b/src/Utils/Physics.elm
index 5da3737..88a4434 100644
--- a/src/Utils/Physics.elm
+++ b/src/Utils/Physics.elm
@@ -2,6 +2,7 @@ module Utils.Physics exposing
   ( getNewPosAndSpeed
   , getMove
   , getWaveMove
+  , getSawToothMove
   )
 
 import Model.Vec2 exposing (..)
@@ -17,24 +18,37 @@ getNewPosAndSpeed dt dir computeSpeed (pos, speed) =
       )
 
 getMove : Float -> Vec2 -> Vec2
-getMove speed dir =
+getMove dist 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
+      in  { x = dist * cos angle
+          , y = dist * sin angle
           }
 
 getWaveMove : Float -> Vec2 -> Float -> Float -> Vec2
-getWaveMove speed dir amplitude period =
-  let move = getMove speed dir
+getWaveMove dist dir amplitude period =
+  let move = getMove dist dir
       perpendMove =
         getMove
           (amplitude * (sin ((norm move) / period)))
           (clockwiseRotate90 move)
   in  move `add` perpendMove
 
+getSawToothMove : Float -> Vec2 -> Float -> Float -> Vec2
+getSawToothMove dist dir amplitude period =
+  let move = getMove dist dir
+      perpendMove =
+        getMove
+          ( let max = 1000 / period
+                middle = max / 2
+                modulo = toFloat <| round (norm move) % round max
+            in  amplitude * (if modulo < middle then modulo else max - modulo) / middle
+          )
+          (clockwiseRotate90 move)
+  in  move `add` perpendMove
+
 getAcc : Vec2 -> Vec2 -> Vec2
 getAcc move speed = (move `div` 300) `sub` (speed `div` 300)