Merge pull request #78 from BlaXpirit/feature/color_subtract

Added subtract function for Colors

include/SFML/Graphics/Color.h

@@ -109,6 +109,17 @@ CSFML_GRAPHICS_API sfUint32 sfColor_toInteger(sfColor color);
 ////////////////////////////////////////////////////////////
 CSFML_GRAPHICS_API sfColor sfColor_add(sfColor color1, sfColor color2);
 
+////////////////////////////////////////////////////////////
+/// \brief Subtract two colors
+///
+/// \param color1 First color
+/// \param color2 Second color
+///
+/// \return Component-wise saturated subtraction of the two colors
+///
+////////////////////////////////////////////////////////////
+CSFML_GRAPHICS_API sfColor sfColor_subtract(sfColor color1, sfColor color2);
+
 ////////////////////////////////////////////////////////////
 /// \brief Modulate two colors
 ///

src/SFML/Graphics/Color.cpp

@@ -97,6 +97,21 @@ sfColor sfColor_add(sfColor color1, sfColor color2)
 }
 
 
+////////////////////////////////////////////////////////////
+sfColor sfColor_subtract(sfColor color1, sfColor color2)
+{
+    int red   = std::max(color1.r - color2.r, 0);
+    int green = std::max(color1.g - color2.g, 0);
+    int blue  = std::max(color1.b - color2.b, 0);
+    int alpha = std::max(color1.a - color2.a, 0);
+
+    return sfColor_fromRGBA(static_cast<sfUint8>(red),
+                            static_cast<sfUint8>(green),
+                            static_cast<sfUint8>(blue),
+                            static_cast<sfUint8>(alpha));
+}
+
+
 ////////////////////////////////////////////////////////////
 sfColor sfColor_modulate(sfColor color1, sfColor color2)
 {