How do I detect areas that touch but don't overlap? SOLVED

merthurian

I am building a drag and drop editing system. The objects that I'm moving are Area2D with CollisionPolygon2D nodes. The polygons are very simple and every point's position consists of whole numbers. Also when I move the objects, I use ceil on their x and y positions to align everything with a 1x1 grid.

I don't want these objects intersect, so I check if get_overlapping_areas() returns anything before dropping. But, I do want the objects to touch on the edges. My problem is that get_overlapping_areas() returns ares that don't overlap but do touch.

How can I get around this?

cybereality

Well, if they are on a grid, you can just search through an Array and do some calculations. Godot does not support multi-dimensional Arrays, but you can emulate this with a 1D Array and an index function. Then you can loop through and see if two neighboring blocks are full.

merthurian

Thanks. That would definitely work but my situation is slightly different. I am using a viewport with its own world to arrange these shapes so it's not a grid, it's world space.

I have since solved the problem like this:

When placing a shape, I check to see if there are any overlapping areas. If there are, I take the returned polygons and use intersect_polygons_2d to generate the intersecting areas. Then I check to see if the combined area of these intersecting areas is zero.

This kills two birds with one stone. I now know if the shapes are overlapping or just touching.

cybereality

Okay, makes sense.