camera.h

#ifndef CAMERA_H
#define CAMERA_H

#include "rtweekend.h"

class camera {
    public:
        camera(
                point3 lookfrom,
                point3 lookat,
                vec3   vup,
                double vfov, 
                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){
            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)
                );
        }

    private:
        point3 origin, lower_left_corner;
        vec3 horizontal, vertical;
        vec3 v, u, w;
        double lens_radius;
        double time0, time1; // shutter open/close times
};

#endif