Expose skin/costume size (#45)

* Expose skin/costume size

* Return skin size as a copy

src/Drawable.js

@@ -380,6 +380,14 @@ Drawable.prototype._setSkinSize = function (width, height, costumeResolution) {
     this.setConvexHullDirty();
 };
 
+/**
+ * Get the size of the Drawable's current skin.
+ * @return {Array.<number>} Skin size, width and height.
+ */
+Drawable.prototype.getSkinSize = function () {
+    return this._uniforms.u_skinSize.slice();
+};
+
 /**
  * Calculate the transform to use when rendering this Drawable.
  * @private

src/RenderWebGL.js

@@ -225,6 +225,15 @@ RenderWebGL.prototype.getBounds = function (drawableID) {
     return bounds;
 };
 
+/**
+ * Get the current skin (costume) size of a Drawable.
+ * @param {int} drawableID The ID of the Drawable to measure.
+ * @return {Array.<number>} Skin size, width and height.
+ */
+RenderWebGL.prototype.getSkinSize = function (drawableID) {
+    const drawable = Drawable.getDrawableByID(drawableID);
+    return drawable.getSkinSize();
+};
 
 /**
  * Check if a particular Drawable is touching a particular color.