toytracer/camera.h

#ifndef CAMERA_H
#define CAMERA_H

#include <cmath>

#include "vec3.h"

class Camera {
  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 t0 = 0, double t1 = 0) {
        auto theta = degrees_to_radians(vfov);
        auto h = std::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 = t0;
        time1 = t1;
    }

    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));
    }

  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
};

#endif // CAMERA_H