fix rounding error when constructing position with negatives

Structs/Position2D.cs

@@ -38,8 +38,8 @@ namespace MoonTools.Core.Structs
 
         public Position2D(float X, float Y)
         {
-            _x = Floor(X);
+            _x = Truncate(X);
-            _y = Floor(Y);
+            _y = Truncate(Y);
             remainder = new Vector2(Remainder(X), Remainder(Y));
         }
 
@@ -147,6 +147,11 @@ namespace MoonTools.Core.Structs
             return (int)Math.Floor(value);
         }
 
+        private static int Truncate(float value)
+        {
+            return (int)Math.Truncate(value);
+        }
+
         public override bool Equals(object other)
         {
             if (other is Position2D otherPosition)

Tests/Position2DTest.cs

@@ -8,6 +8,17 @@ namespace Tests
 {
     public class Position2DTest
     {
+        [Test]
+        public void Negatives()
+        {
+            var position = new Position2D(-3.6f, -4.2f);
+
+            position.X.Should().Be(-3);
+            position.Y.Should().Be(-4);
+            position.ToVector2().X.Should().Be(-3.6f);
+            position.ToVector2().Y.Should().Be(-4.2f);
+        }
+
         [Test]
         public void PositionVectorAddition()
         {