External/HIP/workload/ray-tracing/InOneWeekend/color.h

#ifndef COLOR_H
#define COLOR_H
//==============================================================================================
// Originally written in 2020 by Peter Shirley <ptrshrl@gmail.com>
//
// To the extent possible under law, the author(s) have dedicated all copyright
// and related and neighboring rights to this software to the public domain
// worldwide. This software is distributed without any warranty.
//
// You should have received a copy (see file COPYING.txt) of the CC0 Public
// Domain Dedication along with this software. If not, see
// <http://creativecommons.org/publicdomain/zero/1.0/>.
//
// The original source code is from
//    https://github.com/RayTracing/raytracing.github.io/tree/release/src/InOneWeekend
//
// Changes to the original code follow the following license.
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//==============================================================================================

#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 a linear to gamma transform for gamma 2
  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>(256 * intensity.clamp(r)) << ' '
      << static_cast<int>(256 * intensity.clamp(g)) << ' '
      << static_cast<int>(256 * intensity.clamp(b)) << '\n';
}

#endif