Syntriax.Engine/Engine.Physics2D/Primitives/AABB.cs

using System.Collections.Generic;

using Syntriax.Engine.Core;

namespace Syntriax.Engine.Physics2D.Primitives;

[System.Diagnostics.DebuggerDisplay("LowerBoundary: {LowerBoundary.ToString(), nq}, UpperBoundary: {UpperBoundary.ToString(), nq}")]
public readonly struct AABB(Vector2D LowerBoundary, Vector2D UpperBoundary)
{
    public readonly Vector2D LowerBoundary { get; init; } = LowerBoundary;
    public readonly Vector2D UpperBoundary { get; init; } = UpperBoundary;

    public readonly Vector2D Center => (LowerBoundary + UpperBoundary) * .5f;
    public readonly Vector2D Size => LowerBoundary.FromTo(UpperBoundary).Abs();
    public readonly Vector2D SizeHalf => Size * .5f;

    public static AABB FromVectors(IEnumerable<Vector2D> vectors)
    {
        int counter = 0;

        Vector2D lowerBoundary = new(float.MaxValue, float.MaxValue);
        Vector2D upperBoundary = new(float.MinValue, float.MinValue);

        foreach (Vector2D vector in vectors)
        {
            lowerBoundary = Vector2D.Min(lowerBoundary, vector);
            upperBoundary = Vector2D.Max(upperBoundary, vector);
            counter++;
        }

        if (counter < 2)
            throw new System.ArgumentException($"Parameter {nameof(vectors)} must have at least 2 items.");

        return new(lowerBoundary, upperBoundary);
    }

    public static bool ApproximatelyEquals(AABB left, AABB right)
        => left.LowerBoundary.ApproximatelyEquals(right.LowerBoundary) && left.UpperBoundary.ApproximatelyEquals(right.UpperBoundary);
}

public static class AABBExtensions
{
    public static AABB ToAABB(this IEnumerable<Vector2D> vectors) => AABB.FromVectors(vectors);

    public static bool ApproximatelyEquals(this AABB left, AABB right) => AABB.ApproximatelyEquals(left, right);
}