function change() {
                Crafty.viewport.scroll('_x', -(this.x + (this.w / 2) - (Crafty.viewport.width / 2) - offx));
                Crafty.viewport.scroll('_y', -(this.y + (this.h / 2) - (Crafty.viewport.height / 2) - offy));
                Crafty.viewport._clamp();
            }
@
#Crafty.viewport.follow
@comp Crafty.viewport
@sign public void Crafty.viewport.follow(Object target, Number offsetx, Number offsety)
@param Object target - An entity with the 2D component
@param Number offsetx - Follow target should be offsetx pixels away from center
@param Number offsety - Positive puts target to the right of center

Follows a given entity with the 2D component. If following target will take a portion of
the viewport out of bounds of the world, following will stop until the target moves away.

@example
~~~
var ent = Crafty.e('2D, DOM').attr({w: 100, h: 100:});
Crafty.viewport.follow(ent, 0, 0);
~~~