Better docs for ol.Sphere#offset

src/ol/sphere/sphere.js

@@ -214,12 +214,13 @@ ol.Sphere.prototype.midpoint = function(c1, c2) {
 
 
 /**
- * Returns the coordinate at the given distance and bearing from c.
+ * Returns the coordinate at the given distance and bearing from `c1`.
  *
- * @param {ol.Coordinate} c1 Coordinate.
+ * @param {ol.Coordinate} c1 The origin point (`[lon, lat]` in degrees).
- * @param {number} distance Distance.
+ * @param {number} distance The great-circle distance between the origin
- * @param {number} bearing Bearing.
+ *     point and the target point.
- * @return {ol.Coordinate} Coordinate.
+ * @param {number} bearing The bearing (in radians).
+ * @return {ol.Coordinate} The target point.
  */
 ol.Sphere.prototype.offset = function(c1, distance, bearing) {
   var lat1 = goog.math.toRadians(c1[1]);