using System;

using System.Runtime.InteropServices;

using System.Runtime.CompilerServices;

using System.Numerics;

​

//https://stackoverflow.com/questions/75421336/any-alternative-about-cs0233-for-sizeoft-in-structlayoutattribute

​

public interface IVector3<TVector, TValue> : IAdditionOperators<TVector, TVector, TVector>

    where TValue : unmanaged, INumber<TValue>

    where TVector : IVector3<TVector, TValue>, new ()

{

    TValue X { get; init; }

    TValue Y { get; init; }

    TValue Z { get; init; }

}

​

[StructLayout(LayoutKind.Sequential, Pack = 1/*, Size = 3 * sizeof(T)*/)]

public struct Vector3Double :  IVector3<Vector3Double, double>

{

    public double X { get; init; }

    public double Y { get; init; }

    public double Z { get; init; }

​

    public Vector3Double(double x, double y, double z) => (X, Y, Z) = (x, y, z);

​

    public static Vector3Double operator +(Vector3Double left, Vector3Double right) => new Vector3Double() { X = left.X + right.X, Y = left.Y + right.Y, Z = left.Z + right.Z };

    public static Vector3Double operator checked +(Vector3Double left, Vector3Double right) => new Vector3Double() { X = checked(left.X + right.X), Y = checked(left.Y + right.Y), Z = checked(left.Z + right.Z) };

}

​

public static class VectorExtensions

{

    public static TVector Add<TVector, TValue>(this TVector left, TVector right)

        where TValue : unmanaged, INumber<TValue>

        where TVector : IVector3<TVector, TValue>, new ()

    {

        return new() { X = left.X + right.X, Y = left.Y + right.Y, Z = left.Z + right.Z };

    }

    public static TVector Scale<TVector, TValue>(this TVector left, TValue scale)

        where TValue : unmanaged, INumber<TValue>

        where TVector : IVector3<TVector, TValue>, new ()

    {

        return new() { X = scale*left.X, Y = scale*left.Y, Z = scale*left.Z };

    }

}

​

public class Program

{

    public static void Main()

    {

        try

        {

            Console.WriteLine($"Marshal.SizeOf<Vector3Double>()={Marshal.SizeOf<Vector3Double>()}");

        }

        catch (Exception ex)

        {

            Console.WriteLine($"Marshal.SizeOf<Vector3Double>() failed with exception: {ex}");

        }

        var vec1 = new Vector3Double(1.1, 1.1, 1.1);

        var vec2 = new Vector3Double(2.2, 2.2, 2.2);

​

        var vec3 = vec1 + vec2;

        Console.WriteLine($"vec1 + vec2 = {System.Text.Json.JsonSerializer.Serialize(vec3)}");

        // Compiles

        var v3 = vec1.Add<Vector3Double, double>(vec2);

​

        // This fails to compile

        // The type arguments for method 'VectorExtensions.Add<TVector, TValue>(TVector, TVector)' cannot be inferred from the usage. Try specifying the type arguments explicitly.

        var v32 = vec1.Add(vec2);

​

        // But this compiles.

        var scvec = vec1.Scale(2.2);

    }

}

​