#21 新增gapXY用于平铺/滚动间距

source/src/Math/Vector2.ts

@@ -154,6 +154,17 @@ module es {
             return Math.sqrt((v1 * v1) + (v2 * v2));
         }
 
+        /**
+         * 返回两个向量之间的角度，单位是度数
+         * @param from
+         * @param to
+         */
+        public static angle(from: Vector2, to: Vector2): number{
+            from = Vector2.normalize(from);
+            to = Vector2.normalize(to);
+            return Math.acos(MathHelper.clamp(Vector2.dot(from, to), -1, 1)) * MathHelper.Rad2Deg;
+        }
+
         /**
          * 矢量反演的结果
          * @param value