From a06415f3712be6063bbb1d3f2b593b4d40127fff Mon Sep 17 00:00:00 2001
From: Quinn <henth013@d.umn.edu>
Date: Thu, 6 Apr 2023 10:54:53 -0500
Subject: [PATCH] Added angleDiff() function to vector to get the difference in
 angle from one vector to another.

---
 src/Vector.java       |  6 ++++++
 tests/VectorTest.java | 13 +++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/src/Vector.java b/src/Vector.java
index 64e2823..b1cc038 100644
--- a/src/Vector.java
+++ b/src/Vector.java
@@ -1,3 +1,4 @@
+import static java.lang.Math.acos;
 import static java.lang.Math.sqrt;
 
 public class Vector {
@@ -65,4 +66,9 @@ public class Vector {
         float mag = this.mag();
         return new Vector(x / mag, y / mag, z / mag);
     }
+
+    float angleDiff(Vector other){
+        float dot = this.dot(other);
+        return (float)acos(dot / (this.mag() * other.mag()));
+    }
 }
diff --git a/tests/VectorTest.java b/tests/VectorTest.java
index 8382c28..15243f6 100644
--- a/tests/VectorTest.java
+++ b/tests/VectorTest.java
@@ -81,4 +81,17 @@ class VectorTest{
         assertFloatEquals((float)-216.2, cross.z, (float)0.1);
     }
 
+    @Test
+    public void testAngleDiff(){
+        Vector v1 = new Vector(1, 0);
+        Vector v2 = new Vector(0, 1);
+        Vector v3 = new Vector(-1, 0);
+
+        assertFloatEquals(v1.angleDiff(v1), 0);
+        assertFloatEquals(v1.angleDiff(v2), (float) toRadians(90));
+        assertFloatEquals(v1.angleDiff(v3), (float) toRadians(180));
+        assertFloatEquals(v1.angleDiff(v1.mul(100)), 0);
+        assertFloatEquals(v1.angleDiff(v2.mul(100)), (float) toRadians(90));
+    }
+
 }
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