From 7cc953a44eff42220b2c7813db78610d51aa82be Mon Sep 17 00:00:00 2001
From: Colin McMillen <colin@semicolin.games>
Date: Tue, 11 Feb 2020 17:02:16 -0500
Subject: [PATCH] add extension method: Vector2.Rotate()

GitOrigin-RevId: ee1e84ff188d5a3134dafb1f5150199682c4e063
---
 Shared/Geometry.cs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Shared/Geometry.cs b/Shared/Geometry.cs
index fb9bc94..b5a22e5 100644
--- a/Shared/Geometry.cs
+++ b/Shared/Geometry.cs
@@ -5,6 +5,16 @@ using System;
 
 namespace SemiColinGames {
 
+  public static class Geometry {
+    public static Vector2 Rotate(this Vector2 point, float angle) {
+      float cos = FMath.Cos(angle);
+      float sin = FMath.Sin(angle);
+      return new Vector2(
+        point.X * cos - point.Y * sin,
+        point.Y * cos + point.X * sin);
+    }
+  }
+
   // Math functions that return floats rather than doubles, for convenience.
   public static class FMath {
     public const float PI = (float) Math.PI;