Irregular selections

Hello, I would like to ask how to check if a point is inside an irregular selection. Since 3D is too complicated, I only tried 2D. https://github.com/PEMapModder/smal...rc/pemapmodder/customareas/math/Irregular.php shows my attempt to make it, but it doesn't work with concave shapes. Only convex shapes work with it. I used the formula of y = slope * x + y-intercept to find out if a point is above/on/below a line (as the edge of a shape), so a Vector2 point is inside that shape if for any two adjacent lines it is "inside" (on either line, or above first line and below second line, or above second line and below first line). However, this "inside" theory doesn't work if it is a concave shape. Therefore, I am asking for help here.

P.S. I know @Falk is the expert on these

If you don't know, just don't post.

I knew you would post something like this. You deserve your wikipedia hostmask

What about getting all the integral coordinates inside it? If I test with this point by point, it will be very slow.

For example, set a prism of that shape with a given height to a given type of block.
Which means I need to get a list of the blocks.