using System.Numerics;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;

namespace StgSharp.Math
{
    /// <summary>
    /// A two dimension vector defined by two elements.
    /// Vec2Ds in StgSharp are defaultly usaed as colum vector. 
    /// </summary>
    [StructLayout(LayoutKind.Explicit, Size = 16, Pack = 16)]
    public struct Vec2d
    {

        [FieldOffset(0)]
        public float X;
        [FieldOffset(4)]
        public float Y;

        [FieldOffset(0)]
        internal Vector4 vec;
        [FieldOffset(0)]
        internal Vector2 v;

        public Vec2d(float x, float y)
        {
            v = new Vector2(x, y);
        }

        internal Vec2d(Vector2 vec)
        {
            v = vec;
        }

        public static Vec2d Zero
        {
            get { return new Vec2d(0, 0); }
        }

        public static Vec2d Unit
        {
            get { return new Vec2d(1, 1); }
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Vec2d operator +(Vec2d left, Vec2d right)
        {
            return new Vec2d(left.v + right.v);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static Vec2d operator -(Vec2d left, Vec2d right)
        {
            return new Vec2d(left.v - right.v);
        }

        public static Vec2d operator *(Vec2d vec, float value)
        {
            return new Vec2d(vec.v * value);
        }

        public static Vec2d operator /(Vec2d vec, float value)
        {
            return new Vec2d(vec.v / value);
        }

        public static bool operator ==(Vec2d left, Vec2d right)
        {
            return left.v == right.v;
        }

        public static bool operator !=(Vec2d left, Vec2d right)
        {
            return !(left == right);
        }

        public float Cross(Vec2d right)
        {
            return X * right.Y - Y * right.X;
        }

    }
}