From 8d489b17ccf3085ef1327bc32223c2ccfd0bf021 Mon Sep 17 00:00:00 2001
From: Matthew Mott <orbweaver3d@gmail.com>
Date: Mon, 22 Mar 2021 20:27:50 +0000
Subject: [PATCH] Remove unused Quaternion::createForMatrix()

This method was only used in a single test (which has now been changed to use
createForY() instead, although for some reason this requires a negated angle).
---
 libs/math/CMakeLists.txt |  2 +-
 libs/math/Quaternion.cpp | 55 ----------------------------------------
 libs/math/Quaternion.h   |  5 ----
 test/Brush.cpp           | 21 ++++++++++++---
 test/math/Quaternion.cpp |  2 --
 5 files changed, 18 insertions(+), 67 deletions(-)
 delete mode 100644 libs/math/Quaternion.cpp

diff --git a/libs/math/CMakeLists.txt b/libs/math/CMakeLists.txt
index 2f2fd67206..24c5cca03f 100644
--- a/libs/math/CMakeLists.txt
+++ b/libs/math/CMakeLists.txt
@@ -1,2 +1,2 @@
 add_library(math
-            AABB.cpp Frustum.cpp Matrix4.cpp Plane3.cpp Quaternion.cpp)
+            AABB.cpp Frustum.cpp Matrix4.cpp Plane3.cpp)
diff --git a/libs/math/Quaternion.cpp b/libs/math/Quaternion.cpp
deleted file mode 100644
index 7a482a7fdf..0000000000
--- a/libs/math/Quaternion.cpp
+++ /dev/null
@@ -1,55 +0,0 @@
-#include "Quaternion.h"
-
-#include "Matrix4.h"
-
-Quaternion Quaternion::createForMatrix(const Matrix4& matrix4)
-{
-	Matrix4 transposed = matrix4.getTransposed();
-
-	double trace = transposed[0] + transposed[5] + transposed[10] + 1.0;
-
-	if (trace > 0.0001)
-	{
-		double S = 0.5 / sqrt(trace);
-
-		return Quaternion(
-			(transposed[9] - transposed[6]) * S,
-			(transposed[2] - transposed[8]) * S,
-			(transposed[4] - transposed[1]) * S,
-			0.25f / S
-		);
-	}
-
-	if (transposed[0] >= transposed[5] && transposed[0] >= transposed[10])
-	{
-		double S = 2.0 * sqrt(1.0 + transposed[0] - transposed[5] - transposed[10]);
-
-		return Quaternion(
-			0.25 / S,
-			(transposed[1] + transposed[4]) / S,
-			(transposed[2] + transposed[8]) / S,
-			(transposed[6] + transposed[9]) / S
-		);
-	}
-
-	if (transposed[5] >= transposed[0] && transposed[5] >= transposed[10])
-	{
-		double S = 2.0 * sqrt(1.0 + transposed[5] - transposed[0] - transposed[10]);
-
-		return Quaternion(
-			(transposed[1] + transposed[4]) / S,
-			0.25 / S,
-			(transposed[6] + transposed[9]) / S,
-			(transposed[2] + transposed[8]) / S
-		);
-	}
-
-	double S = 2.0 * sqrt(1.0 + transposed[10] - transposed[0] - transposed[5]);
-	
-	return Quaternion(
-		(transposed[2] + transposed[8]) / S,
-		(transposed[6] + transposed[9]) / S,
-		0.25 / S,
-		(transposed[1] + transposed[4]) / S
-	);
-}
diff --git a/libs/math/Quaternion.h b/libs/math/Quaternion.h
index 6110f5bafa..b7e576ad80 100644
--- a/libs/math/Quaternion.h
+++ b/libs/math/Quaternion.h
@@ -61,11 +61,6 @@ class Quaternion :
 	static Quaternion createForY(double angle);
 	static Quaternion createForZ(double angle);
 
-	/**
-	 * Retrieves the quaternion from the given matrix.
-	 */
-	static Quaternion createForMatrix(const Matrix4& matrix4);
-
 	/**
 	 * Returns this quaternion multiplied by the other one.
 	 */
diff --git a/test/Brush.cpp b/test/Brush.cpp
index 254ace934c..399034818b 100644
--- a/test/Brush.cpp
+++ b/test/Brush.cpp
@@ -10,6 +10,15 @@
 namespace test
 {
 
+// Fuzzy equality assertion for Plane3
+void expectNear(const Plane3& p1, const Plane3& p2, double epsilon)
+{
+    EXPECT_NEAR(p1.normal().x(), p2.normal().x(), epsilon);
+    EXPECT_NEAR(p1.normal().y(), p2.normal().y(), epsilon);
+    EXPECT_NEAR(p1.normal().z(), p2.normal().z(), epsilon);
+    EXPECT_NEAR(p1.dist(), p2.dist(), epsilon);
+}
+
 class BrushTest: public RadiantTest
 {
 protected:
@@ -115,14 +124,18 @@ TEST_F(BrushTest, FacePlaneRotateWithMatrix)
                 Plane3 orig = face.getPlane3();
 
                 // Transform the plane with a rotation matrix
-                Matrix4 rot = Matrix4::getRotation(Vector3(0, 1, 0), 2);
+                const double ANGLE = 2.0;
+                Matrix4 rot = Matrix4::getRotation(Vector3(0, 1, 0), ANGLE);
 
-                Node_getTransformable(_brushNode)->setRotation(Quaternion::createForMatrix(rot));
+                Node_getTransformable(_brushNode)->setRotation(
+                    Quaternion::createForY(-ANGLE)
+                );
                 Node_getTransformable(_brushNode)->freezeTransform();
 
+                double EPSILON = 0.001;
                 EXPECT_NE(face.getPlane3(), orig);
-                EXPECT_EQ(face.getPlane3(), orig.transformed(rot));
-                EXPECT_NEAR(face.getPlane3().normal().getLength(), 1, 0.001);
+                expectNear(face.getPlane3(), orig.transformed(rot), EPSILON);
+                EXPECT_NEAR(face.getPlane3().normal().getLength(), 1, EPSILON);
 
                 return true;
             }
diff --git a/test/math/Quaternion.cpp b/test/math/Quaternion.cpp
index 1152b12e05..3831538686 100644
--- a/test/math/Quaternion.cpp
+++ b/test/math/Quaternion.cpp
@@ -40,8 +40,6 @@ TEST(MathTest, QuaternionForZRotation)
 
     expectNear(zRot, Quaternion(0, 0, sin(angle.asRadians() / 2),
                                 cos(angle.asRadians() / 2)));
-    expectNear(zRot,
-               Quaternion::createForMatrix(Matrix4::getRotationAboutZ(angle)));
 }
 
 TEST(MathTest, QuaternionMultiplication)