added isPowerOfTwo

src/mol-math/misc.ts

 /**
- * Copyright (c) 2018 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ * Copyright (c) 2018-2019 mol* contributors, licensed under MIT, See LICENSE file for more info.
  *
  * @author Alexander Rose <alexander.rose@weirdbyte.de>
  */
@@ -10,4 +10,8 @@ export function degToRad (deg: number) {
 
 export function radToDeg (rad: number) {
     return rad * 57.29578  // rad * 180 / Math.PI
+}
+
+export function isPowerOfTwo (x: number) {
+    return (x !== 0) && (x & (x - 1)) === 0
 }
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