Camera.h

#pragma once

#include "utils.h"


class Camera {
public:
    Camera(
        Point3 lookfrom,
        Point3 lookat,
        Vec3 vup,
        double vfov,
        double aspect_ratio,
        double aperture,
        double focus_dist
    ) {
        // Camera ( right handed coordinate system )
        double theta = degrees_to_radians(vfov);
        double h = focus_dist * tan(theta / 2);
        double viewport_height = 2.0 * h;
        double viewport_width = aspect_ratio * viewport_height;

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

        origin = lookfrom;
        horizontal = viewport_width * u;
        vertical = 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;
};