Test for BasicVector4 casting to C array

libs/math/Vector4.h

@@ -268,19 +268,11 @@ class BasicVector4
             _v[2] / _v[3]);
     }
 
-    /** Implicit cast to C-style array. This allows a Vector4 to be
-     * passed directly to GL functions that expect an array (e.g.
-     * glFloat4dv()). These functions implicitly provide operator[]
-     * as well, since the C-style array provides this function.
-     */
-
-    operator const Element* () const {
-        return _v;
-    }
+    /// Cast to const raw array
+    operator const Element* () const { return _v; }
 
-    operator Element* () {
-        return _v;
-    }
+    // Cast to non-const raw array
+    operator Element* () { return _v; }
 
     /*  Cast this Vector4 onto a Vector3, both const and non-const
      */

test/math/Vector.cpp

@@ -446,4 +446,19 @@ TEST(MathTest, Vector3fAsCArray)
     EXPECT_EQ(array[2], 0);
 }
 
+TEST(MathTest, Vector4AsCArray)
+{
+    Vector4 vec(-15, 15, 36.9, -0.5);
+
+    EXPECT_EQ(&vec.y(), &vec.x() + 1);
+    EXPECT_EQ(&vec.z(), &vec.y() + 1);
+    EXPECT_EQ(&vec.w(), &vec.z() + 1);
+
+    double* array = vec;
+    EXPECT_EQ(array[0], -15);
+    EXPECT_EQ(array[1], 15);
+    EXPECT_EQ(array[2], 36.9);
+    EXPECT_EQ(array[3], -0.5);
+}
+
 }