camera.h

#ifndef CAMERA_H
#define CAMERA_H

#include "common.h"

class camera {
   public:
    camera() {
        auto aspect_ratio = 16.0 / 9.0;
        auto viewport_height = 2.0;
        auto viewport_width = aspect_ratio * viewport_height;
        auto focal_length = 1.0;

        origin = point3(0, 0, 0);
        horizontal = vec3(viewport_width, 0.0, 0.0);
        vertical = vec3(0.0, viewport_height, 0.0);
        lower_left_corner =
            origin - horizontal / 2 - vertical / 2 - vec3(0, 0, focal_length);
    }

    // Create a camera with vfov as vertical field-of-view (in degrees)
    camera(point3 lookfrom, point3 lookat, vec3 vup, double vfov,
           double aspect_ratio, double aperture, double focus_dist) {
        auto theta = degrees_to_radians(vfov);
        auto h = tan(theta / 2);
        auto viewport_height = 2.0 * h;
        auto viewport_width = aspect_ratio * viewport_height;

        w = unit_vector(lookfrom - lookat);
        u = unit_vector(cross(vup, w));
        v = cross(w, u);

        origin = lookfrom;
        horizontal = focus_dist * viewport_width * u;
        vertical = focus_dist * viewport_height * v;
        lower_left_corner =
            origin - horizontal / 2 - vertical / 2 - focus_dist * w;

        lens_radius = aperture / 2;
    }

    ray get_ray(double s, double t) const {
        vec3 rd = lens_radius * random_in_unit_disk();
        vec3 offset = u * rd.x() + v * rd.y();

        return ray(origin + offset, lower_left_corner + s * horizontal +
                                        t * vertical - origin - offset);
    }

   private:
    point3 origin;
    point3 lower_left_corner;
    vec3 horizontal;
    vec3 vertical;
    vec3 u, v, w;
    double lens_radius;
};

#endif