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+#ifndef COLOR_H_D3124023
+#define COLOR_H_D3124023
+
+#include <string>
+
+/**
+ * Encodes a color via additive red, green, and blue chanel values.
+ * Each color chanel value is in the range [0,1]. The alpha value
+ * defines the transparency of the color and is also in [0,1].
+ */
+class Color {
+  public:
+    // Components.
+    float r; /**< value of red chanel   */
+    float g; /**< value of green chanel */
+    float b; /**< value of blue chanel  */
+    float a; /**< value of alpha chanel */
+
+    // constants
+    static const Color White;
+    static const Color Black;
+
+    /**
+     * Constructor.
+     * Initialize from component values.
+     * By default, alpha is initialized to 1.
+     * \param r Value of the red chanel.
+     * \param g Value of the green chanel.
+     * \param b Value of the blue chanel.
+     * \param a Value of the alpha chanel.
+     */
+    Color( float r = 0, float g = 0, float b = 0, float a = 1.0 )
+        : r( r ), g( g ), b( b ), a( a ) { }
+
+    /**
+     * Constructor.
+     * Initialize from array of 8-bit component values (RGB only).
+     * \param arr Array containing component values.
+     */
+    Color( const unsigned char* arr );
+
+    inline Color operator+(const Color& rhs) const
+    {
+      return Color(r + rhs.r, g + rhs.g, b + rhs.b, a + rhs.a);
+    }
+
+    inline Color& operator+=(const Color& rhs)
+    {
+      r += rhs.r;
+      g += rhs.g;
+      b += rhs.b;
+      a += rhs.a;
+      
+      return *this;
+    }
+
+    inline Color operator*(const Color& rhs) const
+    {
+      return Color(r * rhs.r, g * rhs.g, b * rhs.b, a * rhs.a);
+    }
+
+    inline Color& operator*=(const Color& rhs)
+    {
+      r *= rhs.r;
+      g *= rhs.g;
+      b *= rhs.b;
+      a *= rhs.a;
+      
+      return *this;
+    }
+
+    inline Color operator*(float s) const
+    {
+      return Color(r * s, g * s, b * s, a * s);
+    }
+
+    inline Color& operator*=(float s)
+    {
+      r *= s;
+      g *= s;
+      b *= s;
+      a *= s;
+      
+      return *this;
+    }
+
+    inline bool operator==(const Color& rhs) const
+    {
+      return r == rhs.r && g == rhs.g && b == rhs.b && a == rhs.a;
+    }
+
+    inline bool operator!=(const Color& rhs) const
+    {
+      return !operator==( rhs );
+    }
+
+    /**
+     * Construct a Color object from a hexadecimal (8-bit per
+     * component) ASCII string.
+     * Since hexademical strings are typically not used to encode
+     * alpha values, the alpha is set to 1 (opaque) by default.
+     * This method also accepts the string "none", in which case
+     * it returns a color value with alpha zero (transparent).
+     * \return Color constructed from the input hex encoding.
+     */
+    static Color fromHex(const char* s);
+
+    /**
+     * Returns a hexadecimal string #rrggbb encoding this color.
+     * \return the hexadecimal encoding of the color.
+     */
+    std::string toHex() const;
+
+};
+
+// Commutable scalar multiplication.
+inline Color operator*(float s, const Color& c)
+{
+  return c * s;
+}
+
+// Prints components.
+std::ostream& operator<<(std::ostream& os, const Color& c);
+
+#endif /* end of include guard: COLOR_H_D3124023 */