From f05e8537bd637a203cabf40eba1997e1f7c22d88 Mon Sep 17 00:00:00 2001
From: Oliver Booth <me@olivr.me>
Date: Tue, 9 Mar 2021 17:36:55 +0000
Subject: [PATCH] (#35) Add Random.NextUnitVector2

Returns a point which lies on the unit circle
---
 .../RandomExtensions.Numerics.cs              | 37 +++++++++++++++++++
 X10D/src/RandomExtensions/RandomExtensions.cs |  2 +-
 2 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 X10D/src/RandomExtensions/RandomExtensions.Numerics.cs

diff --git a/X10D/src/RandomExtensions/RandomExtensions.Numerics.cs b/X10D/src/RandomExtensions/RandomExtensions.Numerics.cs
new file mode 100644
index 0000000..61fd8dc
--- /dev/null
+++ b/X10D/src/RandomExtensions/RandomExtensions.Numerics.cs
@@ -0,0 +1,37 @@
+#if NET5_0
+using System;
+using System.Numerics;
+using X10D.SingleExtensions;
+
+namespace X10D.RandomExtensions
+{
+    public static partial class RandomExtensions
+    {
+        /// <summary>
+        ///     Returns a <see cref="Vector2" /> with magnitude 1 whose components indicate a random point on the unit circle. 
+        /// </summary>
+        /// <param name="random">The <see cref="System.Random" /> instance</param>
+        /// <returns>
+        ///     A <see cref="Vector2" /> whose <see cref="Vector2.Length()" /> returns 1, and whose components indicate a random
+        ///     point on the unit circle.
+        /// </returns>
+        public static Vector2 NextUnitVector2(this Random random)
+        {
+            if (random is null)
+            {
+                throw new ArgumentNullException(nameof(random));
+            }
+
+            var seed = random.Next();
+            var seededRandom = new Random(seed);
+
+            var angle = seededRandom.NextSingle(0, 360).DegreesToRadians();
+            var x = MathF.Cos(angle);
+            var y = MathF.Sin(angle);
+
+            return new Vector2(x, y);
+        }
+    }
+}
+
+#endif
diff --git a/X10D/src/RandomExtensions/RandomExtensions.cs b/X10D/src/RandomExtensions/RandomExtensions.cs
index 43c9504..088f685 100644
--- a/X10D/src/RandomExtensions/RandomExtensions.cs
+++ b/X10D/src/RandomExtensions/RandomExtensions.cs
@@ -10,7 +10,7 @@ namespace X10D.RandomExtensions
     /// <summary>
     ///     Extension methods for <see cref="System.Random" />.
     /// </summary>
-    public static class RandomExtensions
+    public static partial class RandomExtensions
     {
         internal static readonly Random Random = new();