Math: 8-bit and float RGB and RGBA literals.

Shiny!

doc/matrix-vector.dox

@@ -98,6 +98,14 @@ Vector3i fill(10);                     // {10, 10, 10}
 auto diag2 = Matrix3::fromDiagonal({3.0f, 2.0f, 1.0f});
 @endcode
 
+There are also shortcuts to create a vector with all but one component set to
+zero or one, useful for transformations:
+@code
+auto x = Vector3::xAxis();      // {1.0f, 0.0f, 0.0f}
+auto y = Vector2::yAxis(3.0f);  // {0.0f, 3.0f}
+auto z = Vector3::zScale(3.0f); // {1.0f, 1.0f, 3.0f}
+@endcode
+
 It is possible to create matrices from other matrices and vectors with the same
 row count; vectors from vector and scalar:
 @code
@@ -121,6 +129,30 @@ Math::Matrix2x3<Int>::from(mat) *= 2; // mat == { 4, 8, 12, 2, 6, 10 }
 Note that, unlike constructors, this function has no way to check whether the
 array is long enough to contain all elements, so use with caution.
 
+To make handling of colors easier, their behavior is a bit different with a
+richer feature set. Implicit construction of @ref Color4 from @ref Color3 will
+set the alpha to full value (thus `1.0f` for @ref Color4 and `255` for
+@ref Color4ub):
+@code
+Color4 a = Color3{0.2f, 0.7f, 0.5f};     // {0.2f, 0.7f, 0.5f, 1.0f}
+Color4ub b = Color3ub{0x33, 0xb2, 0x7f}; // {0x33, 0xb2, 0x7f, 0xff}
+@endcode
+
+Similarly to axes in vectors, you can create single color shades too, or create
+a RGB color from HSV representation:
+@code
+auto green = Color3::green();          // {0.0f, 1.0f, 0.0f}
+auto cyan = Color4::cyan(0.5f, 0.95f); // {0.5f, 1.0f, 1.0f, 0.95f}
+auto fadedRed = Color3::fromHSV(219.0_degf, 0.50f, 0.57f)
+@endcode
+
+Lastly, namespace @ref Math::Literals provides convenient `_rgb`/`_rgbf` and
+`_rgba`/`_rgbaf` literals for entering colors in hex representation:
+@code
+Color3ub a = 0x33b27f_rgb;   // {0x33, 0xb2, 0x7f}
+Color4 b = 0x33b27fcc_rgbaf; // {0.2f, 0.7f, 0.5f, 0.8f}
+@endcode
+
 @section matrix-vector-component-access Accessing matrix and vector components
 
 Column vectors of matrices and vector components can be accessed using square

src/Magnum/Math/Color.h

@@ -151,7 +151,8 @@ Conversion from and to HSV is done always using floating-point types, so hue
 is always in range in range @f$ [0.0, 360.0] @f$, saturation and value in
 range @f$ [0.0, 1.0] @f$.
 
-@see @ref Color4, @ref Magnum::Color3, @ref Magnum::Color3ub
+@see @link operator""_rgb() @endlink, @link operator""_rgbf() @endlink,
+    @ref Color4, @ref Magnum::Color3, @ref Magnum::Color3ub
 */
 /* Not using template specialization because some internal functions are
    impossible to explicitly instantiate */
@@ -352,7 +353,8 @@ MAGNUM_VECTORn_OPERATOR_IMPLEMENTATION(3, Color3)
 @brief Four-component (RGBA) color
 
 See @ref Color3 for more information.
-@see @ref Magnum::Color4, @ref Magnum::Color4ub
+@see @link operator""_rgba() @endlink, @link operator""_rgbaf() @endlink,
+    @ref Magnum::Color4, @ref Magnum::Color4ub
 */
 /* Not using template specialization because some internal functions are
    impossible to explicitly instantiate */
@@ -532,6 +534,62 @@ class Color4: public Vector4<T> {
 MAGNUM_VECTORn_OPERATOR_IMPLEMENTATION(4, Color4)
 #endif
 
+namespace Literals {
+
+/** @relatesalso Magnum::Math::Color3
+@brief 8bit-per-channel RGB literal
+
+Example usage:
+@code
+Color3ub a = 0x33b27f_rgb;   // {0x33, 0xb2, 0x7f}
+@endcode
+@see @link operator""_rgba() @endlink, @link operator""_rgbf() @endlink
+*/
+constexpr Color3<UnsignedByte> operator "" _rgb(unsigned long long value) {
+    return {UnsignedByte(value >> 16), UnsignedByte(value >> 8), UnsignedByte(value)};
+}
+
+/** @relatesalso Magnum::Math::Color4
+@brief 8bit-per-channel RGBA literal
+
+Example usage:
+@code
+Color4ub a = 0x33b27fcc_rgba;   // {0x33, 0xb2, 0x7f, 0xcc}
+@endcode
+@see @link operator""_rgb() @endlink, @link operator""_rgbaf() @endlink
+*/
+constexpr Color4<UnsignedByte> operator "" _rgba(unsigned long long value) {
+    return {UnsignedByte(value >> 24), UnsignedByte(value >> 16), UnsignedByte(value >> 8), UnsignedByte(value)};
+}
+
+/** @relatesalso Magnum::Math::Color3
+@brief Float RGB literal
+
+Example usage:
+@code
+Color3 a = 0x33b27f_rgbf;   // {0.2f, 0.7f, 0.5f}
+@endcode
+@see @link operator""_rgbaf() @endlink, @link operator""_rgb() @endlink
+*/
+inline Color3<Float> operator "" _rgbf(unsigned long long value) {
+    return Math::normalize<Color3<Float>>(Color3<UnsignedByte>{UnsignedByte(value >> 16), UnsignedByte(value >> 8), UnsignedByte(value)});
+}
+
+/** @relatesalso Magnum::Math::Color4
+@brief Float RGBA literal
+
+Example usage:
+@code
+Color4 a = 0x33b27fcc_rgbaf;   // {0.2f, 0.7f, 0.5f, 0.8f}
+@endcode
+@see @link operator""_rgbf() @endlink, @link operator""_rgbaf() @endlink
+*/
+inline Color4<Float> operator "" _rgbaf(unsigned long long value) {
+    return Math::normalize<Color4<Float>>(Color4<UnsignedByte>{UnsignedByte(value >> 24), UnsignedByte(value >> 16), UnsignedByte(value >> 8), UnsignedByte(value)});
+}
+
+}
+
 /** @debugoperator{Magnum::Math::Color3} */
 template<class T> inline Corrade::Utility::Debug& operator<<(Corrade::Utility::Debug& debug, const Color3<T>& value) {
     return debug << static_cast<const Vector3<T>&>(value);

src/Magnum/Math/Test/ColorTest.cpp

@@ -44,6 +44,8 @@ struct ColorTest: Corrade::TestSuite::Tester {
     void constructNormalization();
     void constructCopy();
 
+    void literals();
+
     void colors();
 
     void fromHue();
@@ -73,6 +75,8 @@ typedef Math::Color4<UnsignedByte> Color4ub;
 
 typedef Math::Deg<Float> Deg;
 
+using namespace Literals;
+
 ColorTest::ColorTest() {
     addTests({&ColorTest::construct,
               &ColorTest::constructDefault,
@@ -84,6 +88,8 @@ ColorTest::ColorTest() {
               &ColorTest::constructNormalization,
               &ColorTest::constructCopy,
 
+              &ColorTest::literals,
+
               &ColorTest::colors,
 
               &ColorTest::fromHue,
@@ -217,6 +223,20 @@ void ColorTest::constructCopy() {
     CORRADE_COMPARE(d, Color4(1.0f, 0.5f, 0.75f, 0.25f));
 }
 
+void ColorTest::literals() {
+    using namespace Literals;
+
+    constexpr Color3ub a = 0x33b27f_rgb;
+    CORRADE_COMPARE(a, (Color3ub{0x33, 0xb2, 0x7f}));
+
+    constexpr Color4ub b = 0x33b27fcc_rgba;
+    CORRADE_COMPARE(b, (Color4ub{0x33, 0xb2, 0x7f, 0xcc}));
+
+    /* Not constexpr yet */
+    CORRADE_COMPARE(0x33b27f_rgbf, (Color3{0.2f, 0.7f, 0.5f}));
+    CORRADE_COMPARE(0x33b27fcc_rgbaf, (Color4{0.2f, 0.7f, 0.5f, 0.8f}));
+}
+
 void ColorTest::colors() {
     CORRADE_COMPARE(Color3ub::red(75), Color3ub(75, 0, 0));
     CORRADE_COMPARE(Color3ub::green(75), Color3ub(0, 75, 0));