Math: equality comparison for Frustum.

Together with the debug operator it allows for much simpler testing.

src/Magnum/Math/Frustum.h

@@ -61,6 +61,19 @@ template<class T> class Frustum {
         /** @brief Constructor */
         constexpr /*implicit*/ Frustum(const Vector4<T>& left, const Vector4<T>& right, const Vector4<T>& bottom, const Vector4<T>& top, const Vector4<T>& near, const Vector4<T>& far): _data{left, right, bottom, top, near, far} {}
 
+        /** @brief Equality comparison */
+        bool operator==(const Frustum<T>& other) const {
+            for(std::size_t i = 0; i != 6; ++i)
+                if(_data[i] != other._data[i]) return false;
+
+            return true;
+        }
+
+        /** @brief Non-equality comparison */
+        bool operator!=(const Frustum<T>& other) const {
+            return !operator==(other);
+        }
+
         /**
          * @brief Raw data
          * @return One-dimensional array of length `24`.

src/Magnum/Math/Test/FrustumTest.cpp

@@ -38,6 +38,8 @@ struct FrustumTest: Corrade::TestSuite::Tester {
     void construct();
     void constructFromMatrix();
 
+    void compare();
+
     void debug();
 };
 
@@ -49,6 +51,8 @@ FrustumTest::FrustumTest() {
     addTests({&FrustumTest::construct,
               &FrustumTest::constructFromMatrix,
 
+              &FrustumTest::compare,
+
               &FrustumTest::debug});
 }
 
@@ -84,8 +88,37 @@ void FrustumTest::constructFromMatrix() {
     const Frustum frustum = Frustum::fromMatrix(
             Matrix4::perspectiveProjection(90.0_degf, 1.0f, 1.0f, 10.0f));
 
-    CORRADE_COMPARE_AS(frustum.planes(), expected.planes(),
-                       TestSuite::Compare::Container);
+    CORRADE_COMPARE(frustum, expected);
+}
+
+void FrustumTest::compare() {
+    Frustum a{
+        {-1.0f,  2.0f, -3.0f, 0.1f},
+        { 1.0f, -2.0f,  3.0f, 0.2f},
+        {-4.0f,  5.0f, -6.0f, 0.3f},
+        { 4.0f, -5.0f,  6.0f, 0.4f},
+        {-7.0f,  8.0f, -9.0f, 0.5f},
+        { 7.0f,  8.0f,  9.0f, 0.6f}};
+
+    Frustum b{
+        {-1.0f,  2.0f, -3.0f, 0.1f},
+        { 1.0f, -2.0f,  3.0f, 0.2f},
+        {-4.0f,  5.0f, -6.0f, 0.3f + Math::TypeTraits<Float>::epsilon()/2.0f},
+        { 4.0f, -5.0f,  6.0f, 0.4f},
+        {-7.0f,  8.0f, -9.0f, 0.5f},
+        { 7.0f,  8.0f,  9.0f, 0.6f}};
+
+    Frustum c{
+        {-1.0f,  2.0f, -3.0f, 0.1f},
+        { 1.0f, -2.0f,  3.0f, 0.2f},
+        {-4.0f,  5.0f, -6.0f, 0.3f},
+        { 4.0f, -5.0f,  6.0f, 0.4f},
+        {-7.0f,  8.0f, -9.0f, 0.5f + Math::TypeTraits<Float>::epsilon()*2.0f},
+        { 7.0f,  8.0f,  9.0f, 0.6f}};
+
+    CORRADE_VERIFY(a == a);
+    CORRADE_VERIFY(a == b);
+    CORRADE_VERIFY(a != c);
 }
 
 void FrustumTest::debug() {