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|
//! Generates rays from screen coordinates
//!
//! Generates rays in world space from screen coordinates.
//! Future versions should also simulate depth of field.
//!
//! # Examples
//!
//! ```
//! use pathtrace::camera::Camera;
//! use pathtrace::core::{Vector3f, Vector2f, Vector2i};
//!
//! let cam = Camera::new(
//! Vector3f::new(10.0),
//! Vector3f::new(0.0),
//! Vector3f::new_xyz(0.0, 1.0, 0.0),
//! 90.0, Vector2i::new(10.0),
//! );
//!
//! let (r, _) = cam.generate_ray(&Vector2f::new(5.0));
//! let dir = r.direction;
//!
//! assert!(
//! dir.x == -0.44792563 &&
//! dir.y == -0.659974 &&
//! dir.z == -0.6031559
//! );
//!
//! ```
use crate::Float;
use crate::core::{Vector3f, Vector2f, Vector2i, Ray};
/// A simple perspective camera
pub struct Camera {
/// The camera origin in the screen
origin: Vector3f,
/// Vector from camera origin to the screen lower left corner
screen_origin: Vector3f,
/// Scaling vectors from screen_origin
qx: Vector3f,
qy: Vector3f,
}
impl Camera {
/// Create a new camera look at a target
///
/// The field of view specifies how wide the image should be.
/// Currently must be between [0; 180[.
pub fn new(origin: Vector3f, target: Vector3f, up: Vector3f, fov: Float, screensize: Vector2i) -> Camera {
let screensize = Vector2f::from(screensize);
// Calculate translation vectors
let forward = (target - origin).norm();
let right = up.cross(&origin).norm();
let newup = forward.cross(&right).norm();
// Calculate screen size from fov
let aspect = screensize.y / screensize.x;
let width = 2.0 * (fov / 2.0).to_radians().tan();
let height = aspect * width;
// Calculate screen scaling vectors
let qx = right * (width / (screensize.x - 1.0));
let qy = newup * (height / (screensize.y - 1.0));
let screen_origin = forward - (right * (width/2.0)) - (newup * (height/2.0));
Camera {
origin,
screen_origin,
qx,
qy,
}
}
/// Generates a ray a screen space point
///
/// The point coordinates should be between [0,0] (lower left corner) and [screensize.x,
/// screensize.y] (upper right corner)
///
/// Will return a ray and a weight
///
/// The direction of the returned way is normalized
pub fn generate_ray(&self, point: &Vector2f) -> (Ray, Float) {
let mut dir = self.screen_origin + (self.qx * point.x) + (self.qy * point.y);
dir.norm_in();
(
Ray { origin: self.origin, direction: dir },
1.0
)
}
}
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