Grey...
There is an algorithm to do it because I have done such a thing before ( a few years ago actually).
1. Cordon off the whole area of the two rects. Take the MinX, MinY, MaxX and MaxY of the area.
2. Use a scanning function starting at MinX,MinY then simply check if that point is within the area of a rectangle within. If it is, then plot it.
3. Move onto the next point minX+1, MinY etc... Continue until the whole area is done.
Points to note: This method will ensure that you only plot once at a certain point. To increase the speed you can copy a valid plot point (x & y) into an array (instead of plotting) then when scanning has finished you simply read the array and plot all the valid points in one go.
There is an algorithm to do it because I have done such a thing before ( a few years ago actually).
1. Cordon off the whole area of the two rects. Take the MinX, MinY, MaxX and MaxY of the area.
2. Use a scanning function starting at MinX,MinY then simply check if that point is within the area of a rectangle within. If it is, then plot it.
3. Move onto the next point minX+1, MinY etc... Continue until the whole area is done.
Points to note: This method will ensure that you only plot once at a certain point. To increase the speed you can copy a valid plot point (x & y) into an array (instead of plotting) then when scanning has finished you simply read the array and plot all the valid points in one go.