/*
 *  let viewport = (aspect_ratio * 2.0, 2.0);
    let focal_length = 1.0;

    let origin = Vec3::new(0.0, 0.0, 0.0);
    let horizontal = Vec3::new(viewport.0, 0.0, 0.0);
    let vertical = Vec3::new(0.0, viewport.1, 0.0);

    let lower_left_corner = origin - horizontal/2.0 - vertical/2.0 - Vec3::new(0.0, 0.0, focal_length);
 */

use crate::vec3::Vec3;
use crate::ray::Ray;

pub struct Camera {
    pub origin: Vec3,
    pub lower_left_corner: Vec3,
    pub horizontal: Vec3,
    pub vertical: Vec3,
}

impl Camera {
    pub fn new() -> Camera {
        let aspect_ratio = 16.0 / 9.0;
        let vp_height = 2.0;
        let vp_width = aspect_ratio * vp_height;
        let focal_length = 1.0;

        let horiz = Vec3::new(vp_width, 0.0, 0.0);
        let verti = Vec3::new(0.0, vp_height, 0.0);
        let orig = Vec3::zero();

        Camera{
            origin: orig,
            lower_left_corner: orig - horiz/2.0 - verti/2.0 - Vec3::new(0.0, 0.0, focal_length),
            horizontal: horiz,
            vertical: verti,
        }
    }

    pub fn get_ray(&self, u: f32, v: f32) -> Ray {
        let dir =   self.lower_left_corner
                    + self.horizontal * u
                    + self.vertical * v 
                    - self.origin;
        Ray{
            orig: self.origin,
            dir,
        }
    }
}