RayTracing1.0.cpp

#include "utility.h"
#include "hittable_list.h"
#include "sphere.h"
#include "color.h"
#include "camera.h"

#include <iostream>


//returns the color of each ray once it reaches the camera
color ray_color(const ray& r, const hittable& world, int depth) {
    hit_record rec;

    //if ray bounce limit is exceeded, no more light is gathered
    if (depth <= 0) {
        return color(0, 0, 0);
    }

    if (world.hit(r, 0.001, infinity, rec)) {
        point3 target = rec.p + rec.normal + random_unit_vector();
        return 0.5 * ray_color(ray(rec.p, target - rec.p), world, depth - 1);
    }
    
    vec3 unit_direction = unit_vector(r.direction());
    auto t = 0.5 * (unit_direction.y() + 1.0);
    return (1.0 - t) * color(1.0, 1.0, 1.0) + t * color(0.5, 0.7, 1.0);
}


int main()
{
    const auto aspect_ratio = 16.0 / 9.0;
    const int image_width = 800;
    const int image_height = static_cast<int>(image_width / aspect_ratio);
    const int samples_per_pixel = 100;
    const int max_depth = 50;

    std::cout << "P3\n" << image_width << ' ' << image_height << "\n255\n";

    hittable_list world;
    world.add(make_shared<sphere>(point3(0, 0, -1), 0.5));
    world.add(make_shared<sphere>(point3(0, -100.5, -1), 100));
    camera cam;

    //iterates through each ray and writes the image into ppm format
    for (int j = image_height - 1; j >= 0; j--) {
        std::cerr << "\rScanlines remaining: " << j << ' ' << std::flush;
        for (int i = 0; i < image_width; i++) {
            color pixel_color(0, 0, 0);
            for (int s = 0; s < samples_per_pixel; s++) {
                auto u = (i + random_double()) / (image_width );
                auto v = (j + random_double()) / (image_height);
                
                           
                ray r = cam.get_ray(u, v);
                pixel_color += ray_color(r, world, max_depth);
                              
               
            }
            //std::cerr << pixel_color << "\n" << std::flush;
            write_color(std::cout, pixel_color, samples_per_pixel);
        }
    }
    std::cerr << "\nDone.\n";


}