main.cpp

#include "utility.h"


#include "hittable.h"
#include "hittable_list.h"
#include "sphere.h"



 color ray_color(const ray& r,const hittable& world){
  hit_record rec;
  if (world.hit(r, 0,infinity, rec)){
    
    return 0.5 * (rec.normal +color(1,1,1));
  
  }
  
  vec3 unit_direction = unit_vector(r.direction());
  auto a = 0.5*(unit_direction.y() + 1.0);
  return (1.0-a)*color(1.0, 1.0, 1.0) + a*color(0.5, 0.7, 1.0);

}

int main(){
  
  auto aspect_ratio = 16.0/9.0;
  int image_width = 400;

  // Calculate the image height, and ensure that it's at least 1.

  int image_height= int(image_width/aspect_ratio);
  image_height = (image_height < 1) ? 1 : image_height; //check for min image height

  // World

  hittable_list world;

  world.add(make_shared<sphere>(point3(0,0,-1), 0.5)); //small sphere
  world.add(make_shared<sphere>(point3(0,-100.5,-1), 100)); // large ground sphere
  
  // Camera

  auto focal_length = 1.0;
  auto viewport_height = 2.0;
  auto viewport_width = viewport_height * (double(image_width)/image_height);
  auto camera_center = point3(0,0,0); // Camera at origin

  // Calculate the vectors across the horizontal and down the vertical viewport edges.
  
  auto viewport_u = vec3(viewport_width,0,0); // Horizontal
  auto viewport_v = vec3(0, -viewport_height, 0);  // Vertical (negative for downward)


  // Calculate the horizontal and vertical delta vectors from pixel to pixel.
  auto pixel_delta_u = viewport_u/image_width;
  auto pixel_delta_v = viewport_v/image_height;


  // Calculate the location of the upper left pixel.
  auto viewport_upper_left = camera_center-vec3(0, 0, focal_length) - viewport_u/2 - viewport_v/2;
  auto pixel00_loc = viewport_upper_left + 0.5 * (pixel_delta_u + pixel_delta_v);

//why not use -> using namespace std? Considered bad practice because it can create naming conflicts
  std::cout << "P3\n"<< image_width << ' '<< image_height<<"\n255\n";

  for (int j = 0; j < image_height; j++){ // Rows (y-axis)
    std::clog << "\rScanlines remaining:" << (image_height - j) << ' ' << std::flush;
    for (int i = 0; i < image_width; i++){ // Columns (x-axis)
      // Calculate pixel center in viewport
      auto pixel_center = pixel00_loc + (i * pixel_delta_u) + (j * pixel_delta_v);
      auto ray_direction = pixel_center - camera_center;
      ray r(camera_center, ray_direction);

      color pixel_color = ray_color(r,world); 
      write_color(std::cout, pixel_color);    
    }
  }
  std::clog <<"\rDone.                 \n";
}