From 5b9dfe4d2e6010a86e5ae13d3f8796c4cd1298e7 Mon Sep 17 00:00:00 2001
From: John Shaver <john@jshaver.net>
Date: Sat, 17 Jun 2017 00:18:37 -0700
Subject: [PATCH] We have animation!

---
 elm-package.json |  1 +
 main.elm         | 41 +++++++++++++++++++++++++++++------------
 2 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/elm-package.json b/elm-package.json
index 77e289f..d73f055 100644
--- a/elm-package.json
+++ b/elm-package.json
@@ -8,6 +8,7 @@
     ],
     "exposed-modules": [],
     "dependencies": {
+        "elm-lang/animation-frame": "1.0.1 <= v < 2.0.0",
         "elm-lang/core": "5.1.1 <= v < 6.0.0",
         "elm-lang/html": "2.0.0 <= v < 3.0.0",
         "elm-lang/svg": "2.0.0 <= v < 3.0.0",
diff --git a/main.elm b/main.elm
index f7fe629..6521f12 100644
--- a/main.elm
+++ b/main.elm
@@ -1,8 +1,9 @@
 import Html exposing (Html, h1, div, text)
-import Time exposing (Time, second)
+import Time exposing (Time, inMilliseconds)
 import Svg exposing (Svg, svg, g, path)
 import Svg.Attributes exposing (stroke, fill, strokeLinejoin, strokeWidth, width, height, viewBox, d)
 import Svg.Path exposing (pathToString, arcBy, subpath, closed, lineBy, startAt, antiClockwise, clockwise, largestArc)
+import AnimationFrame exposing (times)
 
 
 mOVE_SPEED = 60 -- pixels per second
@@ -12,34 +13,40 @@ hEIGHT = "900"
 
 main : Program Never Model Msg
 main =
-  Html.beginnerProgram 
-    { model = model
+  Html.program 
+    { init = init
     , view = view
     , update = update
+    , subscriptions = subscriptions
     }
 
 
 -- MODEL
 
 type alias Model = 
-    { time : Time}
+    { time : Time }
 
-model : Model
-model = {
-    time = 0
-    }
+init : (Model, Cmd msg)
+init = 
+    ({ time = 0 }
+    ,Cmd.none
+    )
 
 -- UPDATE
 
 type Msg = Tick Time
 
-update : Msg -> Model -> Model
+update : Msg -> Model -> (Model, Cmd Msg )
 update msg model =
     case msg of
         Tick newTime ->
-            { model | time = newTime }
+            ({ model | time = newTime }, Cmd.none)
 
--- SUMSCRIPTIONS
+-- SUBSCRIPTIONS
+
+subscriptions : Model -> Sub Msg
+subscriptions model = 
+    times Tick
 
 -- VIEW
 
@@ -47,7 +54,17 @@ type alias Point = (Float, Float)
 
 render : String -> String -> Model -> Html msg
 render w h model = 
-    svg [ width w, height h, viewBox "0 0 500, 900"] [pacman (250, 450) (degrees 90)]
+    let
+        -- Pull this out into a function to calculate a position in a range
+        --  based off of a cycle time and current number in the cycle.
+        cycleTime = 500
+        maxOpen = 90
+        currentCycleRatio = (model.time |> inMilliseconds |> round) % cycleTime
+        openness = (toFloat currentCycleRatio) / (cycleTime / (2 * maxOpen)) - maxOpen |> abs
+    in
+        svg 
+            [ width w, height h, viewBox "0 0 500, 900"] 
+            [pacman (250, 450) (degrees openness)]
 
 pacman : Point -> Float -> Svg msg
 pacman position openness =