Just an experimental work for studying how this algorithm works.
Build it use the Processing. I use processing-3.5.4 in particular.
Mouse Left Press : draw obstacles
Mouse Right Press : erase obstacles
Mouse Wheel Press : view the g and h value at your mouse position.
Press r : reset
The number on the left-up corner is the calculation time in ms.
The path will be re-calculated when an obstacle appearing on the way only.