How can I randomly place several non-colliding rects?

Question

I\'m working on some 2D games with Pygame. I need to place several objects at the same time randomly without them intersecting. I have tried a few obvious

Answer 1

In my case I had a similar problem except that I had some pre-exiting rectangles inside the overall rectangle. So new rectangles had to be placed around those existing ones.

I used a greedy approach:

• Rectangularize the overall (global) rectangle: create a grid from the sorted x & sorted y coordinates of all rectangles so far. So that will give you an irregular (but rectangular) grid.
• For each grid cell calculate the area, this gives you a matrix of areas.
• Use Kadanes 2D algorithm to find the sub matrix that gives you the maximum area (= the largest free rectangle)
• Place a random rectangle in that free space
• Repeat

This requires a conversion from your original coordinate space to/from the grid space but straightforward to do.

(Note that running Kadene directly on the original, global rectangle takes to long. Going via a grid approximation is plenty fast for my application)