Question

I am using processing within Scala (although I don’t think this is really relevant to my question).

I am constructing a searchtree within a loop that runs until a valid path has been found. That can take a few seconds and I would like to draw the graphical representation of the tree while it is being build so the user can see something is happening.

I tried to solve this by calling redraw() within the loop but that doesn’t work. I guess because redraw() doesn’t force a redraw but only sets a flag that a redraw should be done.

So is there a way I can force a redraw or how would you normally solve such a problem?

Answer 1

@George Profenza’s comment is correct. Processing tasks all happen on the Animation Thread. Any tasks you execute within draw() will lock that thread until they complete. If you want to update the screen while a task is executing, either run the task on a separate thread (beyond the scope of the Processing API, you have to use Java for this), or break the task up into segments and let the draw() method return at the end of each segment so PApplet can render to the screen.