BoundingBox.cs

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namespace Engine {
    public struct BoundingBox : IEquatable<BoundingBox> {
        public Vector3 Min;
 
        public Vector3 Max;
 
        public IEnumerable<Vector3> Corners {
            get {
                yield return new Vector3(Min.X, Min.Y, Min.Z);
                yield return new Vector3(Max.X, Min.Y, Min.Z);
                yield return new Vector3(Min.X, Max.Y, Min.Z);
                yield return new Vector3(Max.X, Max.Y, Min.Z);
                yield return new Vector3(Min.X, Min.Y, Max.Z);
                yield return new Vector3(Max.X, Min.Y, Max.Z);
                yield return new Vector3(Min.X, Max.Y, Max.Z);
                yield return new Vector3(Max.X, Max.Y, Max.Z);
            }
        }
 
        public BoundingBox(float x1, float y1, float z1, float x2, float y2, float z2) {
            Min = new Vector3(x1, y1, z1);
            Max = new Vector3(x2, y2, z2);
        }
 
        public BoundingBox(Vector3 min, Vector3 max) {
            Min = min;
            Max = max;
        }
 
        public BoundingBox(IEnumerable<Vector3> points) {
            ArgumentNullException.ThrowIfNull(points);
            Min = new Vector3(float.PositiveInfinity);
            Max = new Vector3(float.NegativeInfinity);
            foreach (Vector3 point in points) {
                Min.X = MathF.Min(Min.X, point.X);
                Min.Y = MathF.Min(Min.Y, point.Y);
                Min.Z = MathF.Min(Min.Z, point.Z);
                Max.X = MathF.Max(Max.X, point.X);
                Max.Y = MathF.Max(Max.Y, point.Y);
                Max.Z = MathF.Max(Max.Z, point.Z);
            }
            if (Min.X == float.PositiveInfinity) {
                throw new ArgumentException("points");
            }
        }
 
        public static implicit operator BoundingBox((float X1, float Y1, float Z1, float X2, float Y2, float Z2) v) =>
            new(v.X1, v.Y1, v.Z1, v.X2, v.Y2, v.Z2);
 
        public override bool Equals(object obj) => obj is BoundingBox box && Equals(box);
 
        public override int GetHashCode() => Min.GetHashCode() + Max.GetHashCode();
 
        public override string ToString() => $"{Min},{Max}";
 
        public bool Equals(BoundingBox other) => Min == other.Min && Max == other.Max;
 
        public Vector3 Center() => new(0.5f * (Min.X + Max.X), 0.5f * (Min.Y + Max.Y), 0.5f * (Min.Z + Max.Z));
 
        public Vector3 Size() => Max - Min;
 
        public float Volume() {
            Vector3 vector = Size();
            return vector.X * vector.Y * vector.Z;
        }
 
        public bool Contains(Vector3 p) => p.X >= Min.X && p.X <= Max.X && p.Y >= Min.Y && p.Y <= Max.Y && p.Z >= Min.Z && p.Z <= Max.Z;
 
        public bool Intersection(BoundingBox box) => box.Max.X >= Min.X
            && box.Min.X <= Max.X
            && box.Max.Y >= Min.Y
            && box.Min.Y <= Max.Y
            && box.Max.Z >= Min.Z
            && box.Min.Z <= Max.Z;
 
        public bool Intersection(BoundingSphere sphere) {
            if (sphere.Center.X - Min.X > sphere.Radius
                && sphere.Center.Y - Min.Y > sphere.Radius
                && sphere.Center.Z - Min.Z > sphere.Radius
                && Max.X - sphere.Center.X > sphere.Radius
                && Max.Y - sphere.Center.Y > sphere.Radius
                && Max.Z - sphere.Center.Z > sphere.Radius) {
                return true;
            }
            float num = 0f;
            if (sphere.Center.X - Min.X <= sphere.Radius) {
                num += (sphere.Center.X - Min.X) * (sphere.Center.X - Min.X);
            }
            else if (Max.X - sphere.Center.X <= sphere.Radius) {
                num += (sphere.Center.X - Max.X) * (sphere.Center.X - Max.X);
            }
            if (sphere.Center.Y - Min.Y <= sphere.Radius) {
                num += (sphere.Center.Y - Min.Y) * (sphere.Center.Y - Min.Y);
            }
            else if (Max.Y - sphere.Center.Y <= sphere.Radius) {
                num += (sphere.Center.Y - Max.Y) * (sphere.Center.Y - Max.Y);
            }
            if (sphere.Center.Z - Min.Z <= sphere.Radius) {
                num += (sphere.Center.Z - Min.Z) * (sphere.Center.Z - Min.Z);
            }
            else if (Max.Z - sphere.Center.Z <= sphere.Radius) {
                num += (sphere.Center.Z - Max.Z) * (sphere.Center.Z - Max.Z);
            }
            return num <= sphere.Radius * sphere.Radius;
        }
 
        public static BoundingBox Intersection(BoundingBox b1, BoundingBox b2) {
            Vector3 min = Vector3.Max(b1.Min, b2.Min);
            Vector3 max = Vector3.Min(b1.Max, b2.Max);
            return !(max.X > min.X) || !(max.Y > min.Y) || !(max.Z > min.Z) ? default : new BoundingBox(min, max);
        }
 
        public static BoundingBox Union(BoundingBox b1, BoundingBox b2) {
            Vector3 min = Vector3.Min(b1.Min, b2.Min);
            Vector3 max = Vector3.Max(b1.Max, b2.Max);
            return new BoundingBox(min, max);
        }
 
        public static BoundingBox Union(BoundingBox b, Vector3 p) {
            Vector3 min = Vector3.Min(b.Min, p);
            Vector3 max = Vector3.Max(b.Max, p);
            return new BoundingBox(min, max);
        }
 
        public static float Distance(BoundingBox b, Vector3 p) {
            float num = MathUtils.Max(b.Min.X - p.X, 0f, p.X - b.Max.X);
            float num2 = MathUtils.Max(b.Min.Y - p.Y, 0f, p.Y - b.Max.Y);
            float num3 = MathUtils.Max(b.Min.Z - p.Z, 0f, p.Z - b.Max.Z);
            return MathF.Sqrt(num * num + num2 * num2 + num3 * num3);
        }
 
        public static BoundingBox Transform(BoundingBox b, Matrix m) {
            Transform(ref b, ref m, out BoundingBox result);
            return result;
        }
 
        public static void Transform(ref BoundingBox b, ref Matrix m, out BoundingBox result) {
            Vector3[] sourceArray = [
                new(b.Min.X, b.Min.Y, b.Min.Z),
                new(b.Max.X, b.Min.Y, b.Min.Z),
                new(b.Min.X, b.Max.Y, b.Min.Z),
                new(b.Max.X, b.Max.Y, b.Min.Z),
                new(b.Min.X, b.Min.Y, b.Max.Z),
                new(b.Max.X, b.Min.Y, b.Max.Z),
                new(b.Min.X, b.Max.Y, b.Max.Z),
                new(b.Max.X, b.Max.Y, b.Max.Z)
            ];
            Vector3[] array = new Vector3[8];
            Vector3.Transform(sourceArray, 0, ref m, array, 0, 8);
            result = new BoundingBox(array);
        }
 
        public static bool operator ==(BoundingBox a, BoundingBox b) => a.Equals(b);
 
        public static bool operator !=(BoundingBox a, BoundingBox b) => !a.Equals(b);
    }
}