Add usage to ol.structs.Buffer

src/ol/structs/buffer.js

@@ -1,9 +1,20 @@
 goog.provide('ol.structs.Buffer');
 
 goog.require('goog.array');
+goog.require('goog.webgl');
 goog.require('ol.structs.IntegerSet');
 
 
+/**
+ * @enum {number}
+ */
+ol.structs.BufferUsage = {
+  STATIC_DRAW: goog.webgl.STATIC_DRAW,
+  STREAM_DRAW: goog.webgl.STREAM_DRAW,
+  DYNAMIC_DRAW: goog.webgl.DYNAMIC_DRAW
+};
+
+
 /**
  * @define {boolean} Replace unused entries with NaNs.
  */
@@ -15,8 +26,9 @@ ol.BUFFER_REPLACE_UNUSED_ENTRIES_WITH_NANS = goog.DEBUG;
  * @constructor
  * @param {Array.<number>=} opt_arr Array.
  * @param {number=} opt_used Used.
+ * @param {number=} opt_usage Usage.
  */
-ol.structs.Buffer = function(opt_arr, opt_used) {
+ol.structs.Buffer = function(opt_arr, opt_used, opt_usage) {
 
   /**
    * @private
@@ -49,6 +61,13 @@ ol.structs.Buffer = function(opt_arr, opt_used) {
     }
   }
 
+  /**
+   * @private
+   * @type {number}
+   */
+  this.usage_ = goog.isDef(opt_usage) ?
+      opt_usage : ol.structs.BufferUsage.STATIC_DRAW;
+
 };
 
 
@@ -118,6 +137,14 @@ ol.structs.Buffer.prototype.getFreeSet = function() {
 };
 
 
+/**
+ * @return {number} Usage.
+ */
+ol.structs.Buffer.prototype.getUsage = function() {
+  return this.usage_;
+};
+
+
 /**
  * @param {number} size Size.
  * @param {number} offset Offset.