First, the vertices need to be placed on the graph canvas. This is done by clicking the mouse wherever a vertex is desired. Ten random vertices can be placed by clidking on the "Random" button in the control panel. It is important to note that not all vertices MUST be placed first. Rather, vertices can be added and deleted at a later time. Up to 100 vertices can be placed on the graph canvas.
If any vertex is placed incorrectly it can be deleted immediately after being placed by clicking the "Delete Last" button in the control panel. Repeatedly pressing the "Delete Last" button will continue to remove vertices in the opposite order they were placed.
The Graham Scan Algorithm animation can be started by clicking on the "Run" button. The animation can be paused at anytime by pressing the "Pause" button. Pressing the "Init" button will erase any solution edges and just display the vertices. Finally, to change the speed of the animation, move the "Speed" slider forward or backward.
Step 2The solution is complete when the animated blue polygon becomes closed. At this point, more vertices may be added to graph, the animation can be run again, the solution may be cleared, or the whole canvas may be cleared.
That's all there is to it!To see a graphical demo of these instructions, go to the RIOT Convex Hull Applet Demo page. To try the applet out, go to the RIOT Convex Hull Applet.