this post was submitted on 21 Sep 2025
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How to find the area of an Area2D? (sopuli.xyz)
submitted 2 weeks ago by sbeak@sopuli.xyz to c/godot@programming.dev
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I'm making a game where there are many Area2Ds of different countries, but I want to know the size of each country to calculate their surrender limit (bigger countries take longer to surrender, for example).

I don't want to find the area of just one collision2D as some countries have multiple (see island nations, overseas colonies...), but looping that with the children could work if finding area using AREA2ds isn't a thing.

I don't want to simply use the outermost points of a collisionshape2D and draw a big rectangle, as it would make some countries way bigger than they really are (see especially the British and French empires)

Is it possible to find the area of an Area2D? If not, is it possible to calculate the area of CollisionShape2Ds (then I could just loop through the children).

p.s. Country size will not be the only factor for surrender limit, things like equipment stockpiles and something similar to war support in HOI4 might also affect it...

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[–] Bougie_Birdie@piefed.blahaj.zone 3 points 1 week ago* (last edited 1 week ago)

Unfortunately, it looks like drawing a big rectangle is the only method to calculate area that's baked into Godot. You could get the Area2D's CollisionShape2D children, and then for each child you can child.shape.get_rect().get_area()

Now, if you're getting each shape anyway, and you know what kind of shape it is, you can use the appropriate formula to calculate area. For instance, if it's a CircleShape2D, you can check the radius and get something like var area = shape.radius * shape.radius * PI

For a polygon it becomes more complicated. You can get the points of the polygon and then use Geometry2D.triangulate_polygon() to get an array of triangles inside that polygon. You can then calculate the area of each triangle and sum them to get your total area. There's no built-in way to do this, so it's left as an exercise for you.

The question I have to ask: from a design standpoint, is the exact size of each country truly important to the game? For the sake of argument, Canada is a really quite large country, but it's sparsely populated. A lot of the land is frankly not very habitable. If I was going to abstract a surrender-factor, I'd think about "population" filling a role that you're thinking of for "area." If that were the case, you could just attach a property to each country manually. Maybe a little more work upfront depending on how many countries or regions you're including, but it's definitely cognitively simpler.