color.h

#ifndef COLOR_H
#define COLOR_H

#include "vec3.h"

#include <iostream>

using color = vec3;

inline double linear_to_gamma(double linear_component) {
  return sqrt(linear_component);
}

void write_color(std::ostream& out, color pixel_color, int samples_per_pixel) {
  auto r = pixel_color.x();
  auto g = pixel_color.y();
  auto b = pixel_color.z();
  
  // Divide the color by the number of samples.
  auto scale = 1.0 / samples_per_pixel;
  r *= scale;
  g *= scale;
  b *= scale;
  
  // Apply linear to gamma transform.
  r = linear_to_gamma(r);
  g = linear_to_gamma(g);
  b = linear_to_gamma(b);
  
	// Write the translated [0,255] value of each color component.
  static const interval intensity(0.000, 0.999);
	out << static_cast<int>(255.999 * intensity.clamp(r)) << ' '
		<< static_cast<int>(255.999 * intensity.clamp(g)) << ' '
		<< static_cast<int>(255.999 * intensity.clamp(b)) << '\n';
}


void write_color(
  unsigned char& _r, unsigned char& _g, unsigned char& _b,
  color pixel_color,
  int samples_per_pixel)
{
  auto r = pixel_color.x();
  auto g = pixel_color.y();
  auto b = pixel_color.z();
  
  // Divide the color by the number of samples.
  auto scale = 1.0 / samples_per_pixel;
  r *= scale;
  g *= scale;
  b *= scale;
  
  // Apply linear to gamma transform.
  r = linear_to_gamma(r);
  g = linear_to_gamma(g);
  b = linear_to_gamma(b);
  
  // Write the translated [0,255] value of each color component.
  static const interval intensity(0.000, 0.999);
  _r = static_cast<int>(255.999 * intensity.clamp(r));
  _g = static_cast<int>(255.999 * intensity.clamp(g));
  _b = static_cast<int>(255.999 * intensity.clamp(b));
}

#endif