Question

I need to write condition in while(...) where all three shapes will overlap and then use in while loop try to find combination of coordinates for shape which will not overlap other shapes. I have 3 while loops in code – each one for choose pair of coordinates for specific shape.

This code freezes program:

                    xRing = (int) ((getWidth() - ringSize) * (Math.random()));
                yRing = (int) ((getHeight() - ringSize) * (Math.random()));
                while( !( 

                           (xSquare + squareSize) < (xRing)
                        || (xSquare) > (xRing + ringSize )
                        || (ySquare + squareSize) < (yRing)
                        || (ySquare) > (yRing + ringSize)
                        )

                        ||

                        !( 

                           (xSquare2 + square2Size) < (xRing)
                        || (xSquare2) > (xRing + ringSize )
                        || (ySquare2 + square2Size) < (yRing)
                        || (ySquare2) > (yRing + ringSize)
                        )

                        ||

                        !( 

                           (xSquare + squareSize) < (xSquare2)
                            || (xSquare) > (ySquare2 + square2Size )
                            || (ySquare + squareSize) < (ySquare2)
                            || (ySquare) > (ySquare2 + square2Size)
                        )

                    ){
                    xRing = (int) ((getWidth() - ringSize) * (Math.random()));
                    yRing = (int) ((getHeight() - ringSize) * (Math.random()));


                }

and this works, but allows to overlap Square and Square2:

        while( !( 

                           (xSquare + squareSize) < (xRing)
                        || (xSquare) > (xRing + ringSize )
                        || (ySquare + squareSize) < (yRing)
                        || (ySquare) > (yRing + ringSize)
                        )

                        ||

                        !( 

                           (xSquare2 + square2Size) < (xRing)
                        || (xSquare2) > (xRing + ringSize )
                        || (ySquare2 + square2Size) < (yRing)
                        || (ySquare2) > (yRing + ringSize)
                        )

As far as I understand, I have to check each pair for overlap, there is 3 shapes, 3 possible overlap. As I mentioned before with my code logic I can check for overlapping of 2 pairs. When I am adding third condition check- it fails to exit while. All logic seems to me perfectly OK. My loop will exit if it finds first coordinate where no overlap of three shapes is possible.

Actually my short version of code should look like this:

while( not(ring NOT overlaps square 1) or 
       not(ring NOT overlaps square 2) or 
       not(square 1 NOT overlaps square 2) ) {
  ...
}

SOLVED:
I should check for 2 combination (NOT 3) while drawing each shape, so for each while() I have to have different conditions.

Answer 1

You’re basically checking random positions in your rectangle and if all of them are contained by at least two shapes (assuming your condition is correct, I didn’t check that) your loop won’t exit.

It would be better to loop through all the pixels in your rectangle and check them. This way, your loop will stop after all pixels are checked.

As for your condition: I didn’t thoroughly check it but since you’re using a lot of or conditions I assume at least one of the outer ones is true and thus the loop won’t stop.

I assume your 3 top level conditions should read as follows:

while( not(ring overlaps square 1) or 
       not(ring overlaps square 2) or 
       not(square 1 overlaps square 2) ) {
  ...
}

If, for example, square 1 and 2 don’t overlap the condition will always be true and the loop will run forever.