#ifndef CAMERA_H
#define CAMERA_H

#include "rtweekend.h"
#include "vec3.h"
#include "ray.h"

class camera {
	public:
		camera(
				point3 lookfrom,
				point3 lookat,
				vec3 vup,
				double vfov, // vertical field-of-view in degrees,
				double aspect_ratio
		) {
			auto theta = degrees_to_radians(vfov);
			auto h = tan(theta/2);
			auto viewport_height = 2.0 * h;
			auto viewport_width = aspect_ratio * viewport_height;

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

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

		ray get_ray(double s, double t) const {
			return ray(origin, lower_left_corner + s*horizontal + t*vertical - origin);
		}

	private:
		point3 origin;
		point3 lower_left_corner;
		vec3 horizontal;
		vec3 vertical;
};

#endif