Quadtree/BoundingBox2.cs

using System.Numerics;

namespace Quadtree
{
    public enum IntersectionType { Contains, Intersects, Disjoint }

    public class BoundingBox2
    {
        /// <summary>
        /// Vector containing the lowest X and Y coordinates contained in the bounding box.
        /// </summary>
        public Vector2 Min;

        /// <summary>
        /// Vector containing the highest X and Y coordinates contained in the bounding box.
        /// </summary>
        public Vector2 Max;

        public Vector2 Center => (Max + Min) * 0.5f;

        public Vector2 Size => Max - Min;

        public BoundingBox2(Vector2 min, Vector2 max)
        {
            Min = min;
            Max = max;
        }

        public bool Contains(Vector2 position)
        {
            return Min.X <= position.X && position.X <= Max.X && Min.Y <= position.Y && position.Y <= Max.Y;
        }

        public IntersectionType Intersects(BoundingBox2 other)
        {
            if (Min.X <= other.Min.X && other.Max.X <= Max.X && Min.Y <= other.Min.Y && other.Max.Y <= Max.Y)
            {
                return IntersectionType.Contains;
            }
            if ((other.Max.X <= Min.X || Max.X <= other.Min.X) && (other.Max.Y <= Min.Y || Max.Y <= other.Min.Y))
            {
                return IntersectionType.Disjoint;
            }
            return IntersectionType.Intersects;
        }

        public void Translate(Vector2 translation)
        {
            Min += translation;
            Max += translation;
        }

        public void Expand(float expansion)
        {
            Min.X -= expansion;
            Min.Y -= expansion;
            Max.X += expansion;
            Max.Y += expansion;
        }

        public void Include(Vector2 position)
        {
            if (Min.X > position.X)
            {
                Min.X = position.X;
            }
            else if (Max.X < position.X)
            {
                Max.X = position.X;
            }
            if (Min.Y > position.Y)
            {
                Min.Y = position.Y;
            }
            else if (Max.Y < position.Y)
            {
                Max.Y = position.Y;
            }
        }
    }
}