From 3ee5f9b811e514f131def2babf2e0fd01f3fc5e4 Mon Sep 17 00:00:00 2001
From: That_One_Nerd <dev@that-one-nerd.net>
Date: Wed, 26 Jul 2023 09:44:32 -0400
Subject: [PATCH] Using dot product to calculate angle from three verts.

---
 Nerd_STF/Mathematics/Angle.cs | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/Nerd_STF/Mathematics/Angle.cs b/Nerd_STF/Mathematics/Angle.cs
index f691faa..b68b885 100644
--- a/Nerd_STF/Mathematics/Angle.cs
+++ b/Nerd_STF/Mathematics/Angle.cs
@@ -22,7 +22,7 @@ public struct Angle : IAbsolute<Angle>, IAverage<Angle>, IClamp<Angle>, ICloneab
     }
     public float Gradians
     {
-        get => p_deg * 1.11111111111f; // Reciprocal of 9/10 as a constant (10/9)
+        get => p_deg * 1.11111111111f;
         set => p_deg = value * 0.9f;
     }
     public float Normalized
@@ -52,6 +52,15 @@ public struct Angle : IAbsolute<Angle>, IAverage<Angle>, IClamp<Angle>, ICloneab
         _ => throw new ArgumentException("Unknown type.", nameof(valueType)),
     };
 
+    public static Angle FromVerts(Float3 endA, Float3 middleB, Float3 endC)
+    {
+        endA -= middleB;
+        endC -= middleB;
+
+        float dot = Float3.Dot(endA, endC);
+        return Mathf.ArcCos(dot * endA.InverseMagnitude * endC.InverseMagnitude);
+    }
+
     public static Angle Absolute(Angle val) => new(Mathf.Absolute(val.p_deg));
     public static Angle Average(params Angle[] vals) => new(Mathf.Average(SplitArray(Type.Degrees, vals)));
     public static Angle Ceiling(Angle val, Type type = Type.Degrees) =>