Math: explicit one-parameter Point*D constructor.

Was causing improper implicit conversions, such as here (example
directly from unit tests, where it was unintentionally used):

    Vector3 normal;
    Matrix4 transformation;
    auto transformedNormal = transformation*normal;

Not only that it was possible to multiply 4x4 matrix with 3-component
vector, but the resulting type was Point3D which was absolutely
confusing. Currently it must be explicitly converted:

    transformedNormal = transformation*Point3D(normal);

src/Math/Point2D.h

@@ -54,7 +54,14 @@ template<class T> class Point2D: public Vector3<T> {
          * @param xy    Two-component vector
          * @param z     Z component
          */
-        inline constexpr /*implicit*/ Point2D(const Vector2<T>& xy, T z = T(1)): Vector3<T>(xy, z) {}
+        inline constexpr /*implicit*/ Point2D(const Vector2<T>& xy, T z): Vector3<T>(xy, z) {}
+
+        /**
+         * @brief Construct 2D point from 2D vector
+         *
+         * Z component is set to `1`.
+         */
+        inline constexpr explicit Point2D(const Vector2<T>& xy): Vector3<T>(xy, T(1)) {}
 
         /** @copydoc Vector::Vector(const Vector<size, U>&) */
         template<class U> inline constexpr explicit Point2D(const Vector<3, U>& other): Vector3<T>(other) {}

src/Math/Point3D.h

@@ -55,7 +55,14 @@ template<class T> class Point3D: public Vector4<T> {
          * @param xyz   Three-component vector
          * @param w     W component
          */
-        inline constexpr /*implicit*/ Point3D(const Vector3<T>& xyz, T w = T(1)): Vector4<T>(xyz, w) {}
+        inline constexpr /*implicit*/ Point3D(const Vector3<T>& xyz, T w): Vector4<T>(xyz, w) {}
+
+        /**
+         * @brief Construct 3D point from 3D vector
+         *
+         * W component is set to `1`.
+         */
+        inline constexpr explicit Point3D(const Vector3<T>& xyz): Vector4<T>(xyz, T(1)) {}
 
         /** @copydoc Vector::Vector(const Vector<size, U>&) */
         template<class U> inline constexpr explicit Point3D(const Vector<4, U>& other): Vector4<T>(other) {}

src/Math/Test/Matrix3Test.cpp

@@ -48,6 +48,7 @@ class Matrix3Test: public Corrade::TestSuite::Tester {
 typedef Math::Matrix3<float> Matrix3;
 typedef Math::Matrix<2, float> Matrix2;
 typedef Math::Vector2<float> Vector2;
+typedef Math::Point2D<float> Point2D;
 
 Matrix3Test::Matrix3Test() {
     addTests(&Matrix3Test::constructIdentity,
@@ -122,7 +123,7 @@ void Matrix3Test::reflection() {
                      {0.0f,  0.0f, 1.0f});
 
     CORRADE_COMPARE(actual*actual, Matrix3());
-    CORRADE_COMPARE(actual*normal, -normal);
+    CORRADE_COMPARE((actual*Point2D(normal)).vector(), -normal);
     CORRADE_COMPARE(actual, expected);
 }
 

src/Math/Test/Matrix4Test.cpp

@@ -53,6 +53,7 @@ class Matrix4Test: public Corrade::TestSuite::Tester {
 typedef Math::Matrix4<float> Matrix4;
 typedef Math::Matrix<3, float> Matrix3;
 typedef Math::Vector3<float> Vector3;
+typedef Math::Point3D<float> Point3D;
 
 Matrix4Test::Matrix4Test() {
     addTests(&Matrix4Test::constructIdentity,
@@ -170,7 +171,7 @@ void Matrix4Test::reflection() {
                      {     0.0f,       0.0f,       0.0f, 1.0f});
 
     CORRADE_COMPARE(actual*actual, Matrix4());
-    CORRADE_COMPARE(actual*normal, -normal);
+    CORRADE_COMPARE((actual*Point3D(normal)).vector(), -normal);
     CORRADE_COMPARE(actual, expected);
 }
 

src/Primitives/Icosphere.cpp

@@ -54,7 +54,8 @@ Icosphere<0>::Icosphere(): MeshData3D(Mesh::Primitive::Triangles, new std::vecto
     {0.0f, 0.525731f, -0.850651f},
     {0.0f, 0.525731f, 0.850651f}
 }}, {}) {
-    positions(0)->assign(normals(0)->begin(), normals(0)->end());
+    positions(0)->reserve(normals(0)->size());
+    for(auto i: *normals(0)) positions(0)->push_back(Point3D(i));
 }
 
 }}