camera.h

#ifndef CAMERA_H
#define CAMERA_H

#include "rtweekend.h"

class camera {
private:
    point3 origin;
    point3 lower_left_corner;
    vec3 horizontal;
    vec3 vertical;
    vec3 u, v, w;
    double lens_radius;
    double time0, time1;    // shutter open/close times
public:
    camera(
        point3 lookfrom,
        point3 lookat,
        vec3 vup,
        double vfov,    // vertical field-of-view in degrees
        double aspect_ratio,
        double aperture,
        double focus_dist,
        double _time0 = 0,
        double _time1 = 0
    ) {
        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;
        time0 = _time0;
        time1 = _time1;
    }

    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,
            random_double(time0, time1));
    }
};

# endif