main.cpp

#include "Color.h"
#include "Ray.h"
#include "vec3.h"

#include <iostream>
#include <fstream>

using namespace Color;

color ray_color(const Ray& r) {
    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;

    int image_height = int(image_width / aspect_ratio);
    image_height = (image_height < 1) ? 1 : image_height;


    auto focal_length = 1.0;
    auto viewport_height = 2.0;
    auto viewport_width = viewport_height * (double(image_width)/image_height);
    auto camera_center = vec3(0, 0, 0);

    auto viewport_u = vec3(viewport_width, 0, 0);
    auto viewport_v = vec3(0, -viewport_height, 0);

    auto pixel_delta_u = viewport_u / image_width;
    auto pixel_delta_v = viewport_v / image_height;

    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);

    std::ofstream out("image.ppm");
    std::cout << "P3\n" << image_width << " " << image_height << "\n255\n";

    for (int j = 0; j < image_height; j++) {
        std::clog << "\rScanlines remaining: " << (image_height - j) << ' ' << std::flush;
        for (int i = 0; i < image_width; i++) {
            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);
            write_color(std::cout, pixel_color);
        }
    }

    std::clog << "\rDone.                 \n";
}