Quad-edge data structure

OK, imagine you have a really cool toy that lets you build shapes with straight lines. It's called a quad-edge data structure.

At first, you can only make triangle shapes using only three lines that connect at the corners of the triangle. But with quad-edge, you can add another line to make a square shape or even more lines to make a cool polygon shape.

Now, this toy is really smart too. It can remember which lines connect to which corners and how they all fit together to make the shape you want. It's like a map in your head that tells you how to get from one corner to another.

And if you want to change the shape, you don't have to start from scratch. You can just move around the lines and the structure will automatically adjust to keep track of everything.

So to sum it up, quad-edge is a cool toy that helps you build shapes with straight lines and keeps track of how everything connects together.