diff --git a/source/scripts/engine.js b/source/scripts/engine.js
index 1846dfd..4f1d42d 100644
--- a/source/scripts/engine.js
+++ b/source/scripts/engine.js
@@ -124,6 +124,7 @@ var Window = {
   }
 };
 
+
 var Color = {
   white: [255,255,255,255],
   blue: [84,110,255,255],
@@ -311,7 +312,14 @@ var timer = {
     }
       
     var t = clone(this);
-    t.id = make_timer(this.guardfn.bind(t,fn), secs, obj);
+    t.callback = fn;
+    var guardfn = function() {
+      if (typeof t.callback === 'function')
+        t.callback();
+      else
+        Log.warn("Timer trying to execute without a function.");
+    };
+    t.id = make_timer(guardfn, secs, obj);
     
     return t;
   },
@@ -336,8 +344,40 @@ var timer = {
   kill() { cmd(27, this.id); },
   set time(x) { cmd(28, this.id, x); },
   get time() { return cmd(29, this.id); },
+  get pct() { return this.remain / this.time; },
 };
 
+var Tween = {
+  default: {
+    ease: "inout", /* easing at end and beginning of tween */
+    loop: "restart", /* none, restart, yoyo, increment */
+    time: 1, /* seconds to do */
+  },
+  
+  start(target, start, end, options)
+  {
+    var defn = Object.create(this.default);
+    Object.apply(defn, options);
+    
+    var newtimer = timer.make(null, defn.time, null, true);
+    newtimer.pause();
+    
+    var tween_fn = function() {
+      Log.warn(newtimer.pct);
+    };
+    timer.callback = tween_fn;
+    timer.callback();
+    timer.start();
+  },
+
+  lerp(s, e, t)
+  {
+    t = Math.clamp(t,0,1);
+    return ((e - s) * t) + s;
+  },
+};
+
+
 var animation = {
   time: 0,
   loop: false,
diff --git a/source/shaders/slice9_f.glsl b/source/shaders/slice9_f.glsl
index eb63808..d6524a2 100644
--- a/source/shaders/slice9_f.glsl
+++ b/source/shaders/slice9_f.glsl
@@ -32,6 +32,6 @@ uv9slice(vec2 uv, vec2 s, vec4 b)
 
 void main()
 {
-  uv = uv9slice(uv, scale, border);
+  vec2 nuv = uv9slice(uv, scale, border);
   color = fcolor * texture(image, uv);
 }
diff --git a/source/shaders/slice9_v.glsl b/source/shaders/slice9_v.glsl
index 3ce5ca3..0e18f8c 100644
--- a/source/shaders/slice9_v.glsl
+++ b/source/shaders/slice9_v.glsl
@@ -1,7 +1,7 @@
 #version 330 core
 
 layout (location = 0) in vec2 vert;
-layout (location = 1) in vec2 uv;
+layout (location = 1) in vec2 vuv;
 layout (location = 2) in vec4 vborder;
 layout (location = 3) in vec2 vscale;
 layout (location = 4) in vec4 vcolor;
@@ -17,7 +17,7 @@ void main()
 {
   gl_Position = projection * vec4(vert, 0.0, 1.0);
   
-  uv = vert;
+  uv = vuv;
   border = vborder;
   scale = vscale;
   fcolor = vcolor;