Implement translation rotation zoom using uniform buffers, improvement?

shader/circle.vert

@@ -10,10 +10,25 @@ uniform float zoom;
 uniform vec2 translation;
 uniform float rotation;
 
+vec2 tran(vec2 v)
+{
+  return (v -  translation);
+}
+vec2 rot(vec2 v)
+{
+  return vec2 ( v.x * cos(-rotation) - v.y * sin(-rotation)
+              , v.x * sin(-rotation) + v.y * cos(-rotation)
+              );
+}
+vec2 scal(vec2 v)
+{
+  return vec2 ( 2 * v.x * zoom / winSize.x
+              , 2 * v.y * zoom / winSize.y
+          );
+}
 void main()
 {
-  gl_Position = vec4(position,1);
-  //gl_Position = vec4(0,0,0,1);
+  gl_Position = vec4(scal(rot(tran(position.xy))),position.z,1);
   vColor = color;
   vRad = rad;
 }