+ * Convenience wrapper around colorAtPixel if you only care about RGB (not A).
+ * @param {number} x The screen x-coordinate at which to sample.
+ * @param {number} y The screen y-coordinate at which to sample.
+ * @return {Array.<number>} a 3D array: [R, G, B]. All three values
+ * are in [0, 255]. A pixel which has never been touched will be [0,0,0].
+ */
+PixelSampler.prototype.rgbAtPixel = function(x, y) {
+ return this.colorAtPixel(x, y).slice(0, 3);
+};
+
+/**