added threading

Author: MarcoCiaramella

androidgpulib/src/main/java/com/lib/androidgpulib/AndroidGPU.java

@@ -40,7 +40,7 @@ public AndroidGPU(String glsl) throws Exception {
     /**
      * Runs the GLSL code.
      * @param activity
-     * @param callback function called on UI thread when GPU task ends
+     * @param callback function called on UI thread when GPU task ends. output must be read here.
      * @param dim_x data dimension along X
      * @param dim_y data dimension along Y
      * @param dim_z data dimension along Z