Add precise animation loop

framer/AnimationLoop.coffee

@@ -5,25 +5,34 @@ Utils = require "./Utils"
 {Config} = require "./Config"
 {EventEmitter} = require "./EventEmitter"
 
+if window.performance
+	getTime = -> window.performance.now()
+else
+	getTime = -> Date.now()
+
+
 class exports.AnimationLoop extends EventEmitter
 
+	constructor: ->
+		@_delta = 1/60
+
 	start: =>
 
 		animationLoop = @
 
-		_timestamp = null
+		_timestamp = getTime()
 
 
 		tick = (timestamp) ->
 
 			window.requestAnimationFrame(tick)
 
-			# if _timestamp
-			# 	delta = (timestamp - _timestamp) / 1000
-			# else
-			# 	delta = 1/60
-
-			delta = 1/60
+			if animationLoop._delta
+				delta = animationLoop._delta
+			else
+				timestamp = getTime()
+				delta = (timestamp - _timestamp) / 1000
+				_timestamp = timestamp
 
 			animationLoop.emit("update", delta)
 			animationLoop.emit("render", delta)