Add multithreaded ray tracer implementation

include/color.h

@@ -0,0 +1,37 @@
+#ifndef COLOR_H
+#define COLOR_H
+#include "interval.h"
+
+#include "vec3.h"
+
+#include <iostream>
+
+using color = vec3;
+inline double linear_to_gamma(double linear_component)
+{
+    if (linear_component > 0)
+        return std::sqrt(linear_component);
+
+    return 0;
+}
+inline void write_color(std::ostream& out, const color& pixel_color) {
+    auto r = pixel_color.x();
+    auto g = pixel_color.y();
+    auto b = pixel_color.z();
+
+        // Apply a linear to gamma transform for gamma 2
+    r = linear_to_gamma(r);
+    g = linear_to_gamma(g);
+    b = linear_to_gamma(b);
+
+    // Translate the [0,1] component values to the byte range [0,255].
+    static const interval intensity(0.000, 0.999);
+    int rbyte = int(256 * intensity.clamp(r));
+    int gbyte = int(256 * intensity.clamp(g));
+    int bbyte = int(256 * intensity.clamp(b));
+
+    // Write out the pixel color components.
+    out << rbyte << ' ' << gbyte << ' ' << bbyte << '\n';
+}
+
+#endif