Added animation frame callback

main.js

@@ -2,6 +2,11 @@
 
 // Game state
 var gs={
+  // Animation frame of reference
+  step:(1/60), // target step time @ 60 fps
+  acc:0, // accumulated time since last frame
+  lasttime:0, // time of last frame
+
   // Canvas object
   canvas:null,
   ctx:null,
@@ -19,6 +24,31 @@ var gs={
   timeline:new timelineobj()
 };
 
+// Called once per frame
+function rafcallback(timestamp)
+{
+  // First time round, just save epoch
+  if (gs.lasttime>0)
+  {
+    // Determine accumulated time since last call
+    gs.acc+=((timestamp-gs.lasttime) / 1000);
+
+    // If it's more than 15 seconds since last call, reset
+    if ((gs.acc>gs.step) && ((gs.acc/gs.step)>(60*15)))
+      gs.acc=gs.step*2;
+
+    // Process the "steps" since last call
+    while (gs.acc>gs.step)
+      gs.acc-=gs.step;
+  }
+
+  // Remember when we were last called
+  gs.lasttime=timestamp;
+
+  // Request that we are called on the next frame
+  window.requestAnimationFrame(rafcallback);
+}
+
 // Startup called once when page is loaded
 function startup()
 {
@@ -35,6 +65,8 @@ function startup()
 
   write(gs.ctx, 100, 100, "TEST", 10, "#FF00FF");
 
+  window.requestAnimationFrame(rafcallback);
+
   console.log(models);
   console.log(gs);
 }