Remove unused Matrix4::isEqual()

Also add a simple test for Matrix4 equality using the regular operator==
method.

libs/math/Matrix4.h

@@ -420,11 +420,6 @@ class Matrix4
      */
     bool operator!=(const Matrix4& other) const;
 
-    /**
-     * Returns true if self and other are element-wise equal within epsilon.
-     */
-    bool isEqual(const Matrix4& other, double epsilon) const;
-
     /**
      * Returns true if this and the given matrix are exactly element-wise equal.
      * This and the other matrix must be affine.
@@ -638,26 +633,6 @@ inline bool Matrix4::operator!=(const Matrix4& other) const
     return !operator==(other);
 }
 
-inline bool Matrix4::isEqual(const Matrix4& other, double epsilon) const
-{
-    return float_equal_epsilon(xx(), other.xx(), epsilon)
-        && float_equal_epsilon(xy(), other.xy(), epsilon)
-        && float_equal_epsilon(xz(), other.xz(), epsilon)
-        && float_equal_epsilon(xw(), other.xw(), epsilon)
-        && float_equal_epsilon(yx(), other.yx(), epsilon)
-        && float_equal_epsilon(yy(), other.yy(), epsilon)
-        && float_equal_epsilon(yz(), other.yz(), epsilon)
-        && float_equal_epsilon(yw(), other.yw(), epsilon)
-        && float_equal_epsilon(zx(), other.zx(), epsilon)
-        && float_equal_epsilon(zy(), other.zy(), epsilon)
-        && float_equal_epsilon(zz(), other.zz(), epsilon)
-        && float_equal_epsilon(zw(), other.zw(), epsilon)
-        && float_equal_epsilon(tx(), other.tx(), epsilon)
-        && float_equal_epsilon(ty(), other.ty(), epsilon)
-        && float_equal_epsilon(tz(), other.tz(), epsilon)
-        && float_equal_epsilon(tw(), other.tw(), epsilon);
-}
-
 inline bool Matrix4::isAffineEqual(const Matrix4& other) const
 {
     return xx() == other.xx() &&

test/math/Matrix4.cpp

@@ -99,6 +99,18 @@ TEST(MathTest, ConstructMatrixByRows)
     EXPECT_EQ(m.translation(), Vector3(0.34, 9, 20));
 }
 
+TEST(MathTest, MatrixEquality)
+{
+    Matrix4 m1 = Matrix4::byRows(1, 2, 3.5, 4,
+                                 5, -6, 17, 800,
+                                 9.01, 10, 11, 12.4,
+                                 200, -10, 300, 400);
+    Matrix4 m2 = m1;
+    EXPECT_TRUE(m1 == m2);
+    EXPECT_TRUE(m1 != Matrix4::getIdentity());
+    EXPECT_TRUE(m2 != Matrix4::getIdentity());
+}
+
 TEST(MathTest, MatrixRotationAboutXDegrees)
 {
     double angle = 30.0;