Math: added convenience function Vector::resized().

src/Math/Test/VectorTest.cpp

@@ -80,6 +80,7 @@ class VectorTest: public Corrade::TestSuite::Tester {
         void length();
         void lengthInverted();
         void normalized();
+        void resized();
 
         void sum();
         void product();
@@ -126,6 +127,7 @@ VectorTest::VectorTest() {
               &VectorTest::length,
               &VectorTest::lengthInverted,
               &VectorTest::normalized,
+              &VectorTest::resized,
 
               &VectorTest::sum,
               &VectorTest::product,
@@ -317,7 +319,15 @@ void VectorTest::lengthInverted() {
 }
 
 void VectorTest::normalized() {
-    CORRADE_COMPARE(Vector4(1.0f, 1.0f, 1.0f, 1.0f).normalized(), Vector4(0.5f, 0.5f, 0.5f, 0.5f));
+    const auto vec = Vector4(1.0f, 1.0f, 1.0f, 1.0f).normalized();
+    CORRADE_COMPARE(vec, Vector4(0.5f, 0.5f, 0.5f, 0.5f));
+    CORRADE_COMPARE(vec.length(), 1.0f);
+}
+
+void VectorTest::resized() {
+    const auto vec = Vector4(2.0f, 2.0f, 0.0f, 1.0f).resized(9.0f);
+    CORRADE_COMPARE(vec, Vector4(6.0f, 6.0f, 0.0f, 3.0f));
+    CORRADE_COMPARE(vec.length(), 9.0f);
 }
 
 void VectorTest::sum() {

src/Math/Vector.h

@@ -455,7 +455,7 @@ template<std::size_t size, class T> class Vector {
          * values. @f[
          *      |\boldsymbol a| = \sqrt{\boldsymbol a \cdot \boldsymbol a}
          * @f]
-         * @see lengthInverted(), Math::sqrt(), normalized()
+         * @see lengthInverted(), Math::sqrt(), normalized(), resized()
          * @todo something like std::hypot() for possibly better precision?
          */
         inline T length() const {
@@ -468,7 +468,7 @@ template<std::size_t size, class T> class Vector {
          * @f[
          *      \frac{1}{|\boldsymbol a|} = \frac{1}{\sqrt{\boldsymbol a \cdot \boldsymbol a}}
          * @f]
-         * @see length(), Math::sqrtInverted(), normalized()
+         * @see length(), Math::sqrtInverted(), normalized(), resized()
          */
         inline T lengthInverted() const {
             return T(1)/length();
@@ -477,12 +477,27 @@ template<std::size_t size, class T> class Vector {
         /**
          * @brief Normalized vector (of unit length)
          *
-         * @see isNormalized()
+         * @see isNormalized(), lengthInverted(), resized()
          */
         inline Vector<size, T> normalized() const {
             return *this*lengthInverted();
         }
 
+        /**
+         * @brief Resized vector
+         *
+         * Convenience equivalent to the following code. Due to operation order
+         * this function is faster than the obvious way of sizing normalized()
+         * vector.
+         * @code
+         * vec*(vec.lengthInverted()*length) // the brackets are important
+         * @endcode
+         * @see normalized()
+         */
+        inline Vector<size, T> resized(T length) const {
+            return *this*(lengthInverted()*length);
+        }
+
         /**
          * @brief %Vector projected onto line
          *
@@ -701,7 +716,12 @@ extern template Corrade::Utility::Debug MAGNUM_EXPORT operator<<(Corrade::Utilit
         return Math::Vector<size, T>::operator/(other);                     \
     }                                                                       \
                                                                             \
-    inline Type<T> normalized() const { return Math::Vector<size, T>::normalized(); } \
+    inline Type<T> normalized() const {                                     \
+        return Math::Vector<size, T>::normalized();                         \
+    }                                                                       \
+    inline Type<T> resized(T length) const {                                \
+        return Math::Vector<size, T>::resized(length);                      \
+    }                                                                       \
     inline Type<T> projected(const Math::Vector<size, T>& other) const {    \
         return Math::Vector<size, T>::projected(other);                     \
     }