remove monogame dependency

Structs/MathHelper.cs

@@ -0,0 +1,10 @@
+namespace MoonTools.Core.Structs
+{
+    public static class MathHelper
+    {
+        public static double ToRadians(double angle)
+        {
+            return (System.Math.PI / 180) * angle;
+        }
+    }
+}

Structs/Position2D.cs

@@ -1,5 +1,5 @@
 using System;
-using Microsoft.Xna.Framework;
+using System.Numerics;
 
 namespace MoonTools.Core.Structs
 {

Structs/Structs.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFramework>netstandard2.1</TargetFramework>
     <RootNamespace>MoonTools.Core.Structs</RootNamespace>
     <PackageId>MoonTools.Core.Structs</PackageId>
     <Version>1.1.0</Version>
@@ -14,7 +14,4 @@
     <PackageProjectUrl>https://github.com/MoonsideGames/MoonTools.Core.Structs</PackageProjectUrl>
     <PackageLicenseExpression>LGPL-3.0-only</PackageLicenseExpression>
   </PropertyGroup>
-  <ItemGroup>
-    <PackageReference Include="MonoGame.Framework.DesktopGL.Core" Version="3.7.0.7" />
-  </ItemGroup>
 </Project>

Structs/Transform2D.cs

@@ -1,5 +1,5 @@
 using System;
-using Microsoft.Xna.Framework;
+using System.Numerics;
 
 namespace MoonTools.Core.Structs
 {
@@ -16,7 +16,7 @@ namespace MoonTools.Core.Structs
         private float _rotation;
         private Vector2 _scale;
 
-        public Matrix TransformMatrix { get; private set; }
+        public Matrix4x4 TransformMatrix { get; private set; }
 
         public Position2D Position
         {
@@ -119,11 +119,11 @@ namespace MoonTools.Core.Structs
             return new Transform2D(Position + other.Position, Rotation + other.Rotation, Scale * other.Scale);
         }
 
-        private static Matrix CreateTransformMatrix(Position2D translation, float rotationDegrees, Vector2 scale)
+        private static Matrix4x4 CreateTransformMatrix(Position2D translation, float rotation, Vector2 scale)
         {
-            return Matrix.CreateScale(scale.X, scale.Y, 1) *
-                Matrix.CreateRotationZ(Microsoft.Xna.Framework.MathHelper.ToRadians(rotationDegrees)) *
-                Matrix.CreateTranslation(translation.X, translation.Y, 0);
+            return Matrix4x4.CreateScale(scale.X, scale.Y, 1) *
+                Matrix4x4.CreateRotationZ(rotation) *
+                Matrix4x4.CreateTranslation(translation.X, translation.Y, 0);
         }
 
         public override bool Equals(Object other)

Tests/Position2DTest.cs

@@ -1,7 +1,8 @@
 using FluentAssertions;
-using Microsoft.Xna.Framework;
 using NUnit.Framework;
+
 using MoonTools.Core.Structs;
+using System.Numerics;
 
 namespace Tests
 {

Tests/Transform2DTest.cs

@@ -1,7 +1,8 @@
 using FluentAssertions;
-using Microsoft.Xna.Framework;
 using NUnit.Framework;
+
 using MoonTools.Core.Structs;
+using System.Numerics;
 
 namespace Tests
 {