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use crate::Vec3;
/// A ray in 3-dimensional space: a line through space with a starting point and a direction.
///
/// Any point on the ray can be found through the formula `origin + t * dir`,
/// where t is a non-negative floating point value, which represents the distance
/// along the ray.
#[derive(Clone, Copy, Default, PartialEq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
#[cfg_attr(feature = "speedy", derive(speedy::Writable, speedy::Readable))]
pub struct Ray3 {
/// Start of the ray
pub origin: Vec3,
/// Direction of the ray, normalized
pub dir: Vec3,
}
impl Ray3 {
/// An invalid ray, starting at the origin and going nowhere.
pub const ZERO: Self = Self {
origin: Vec3::ZERO,
dir: Vec3::ZERO,
};
/// `dir` should be normalized
#[inline]
pub fn from_origin_dir(origin: Vec3, dir: Vec3) -> Self {
Self { origin, dir }
}
/// Get normalized ray (where `dir.len() == 1`).
#[inline]
#[must_use]
pub fn normalize(&self) -> Self {
Self {
origin: self.origin,
dir: self.dir.normalize(),
}
}
/// Returns a new ray that has had its origin moved a given distance forwards along the ray.
///
/// If the ray direction is normalized then the `t` parameter corresponds to the world space distance it moves.
#[inline]
#[must_use]
pub fn offset_along_ray(&self, t: f32) -> Self {
Self {
origin: self.origin + self.dir * t,
dir: self.dir,
}
}
/// True if every value is finite
#[inline]
pub fn is_finite(&self) -> bool {
self.origin.is_finite() && self.dir.is_finite()
}
#[inline]
pub fn point_along(&self, t: f32) -> Vec3 {
self.origin + t * self.dir
}
/// Returns the line segment where `self` and `other` are the closest to each other.
/// If the rays are parallel then non-finite points are returned.
pub fn closest_points(&self, other: &Self) -> (Vec3, Vec3) {
// https://en.wikipedia.org/wiki/Skew_lines#Nearest_Points
let (self_t, other_t) = self.closest_ts(other);
(self.point_along(self_t), other.point_along(other_t))
}
/// Returns the distance along both rays which together form
/// line segment where `self` and `other` are the closest to each other.
/// If the rays are parallel then non-finite values are returned.
pub fn closest_ts(&self, other: &Self) -> (f32, f32) {
// https://en.wikipedia.org/wiki/Skew_lines#Nearest_Points
let (a, b) = (self, other);
let n = a.dir.cross(b.dir);
let n_a = a.dir.cross(n);
let n_b = b.dir.cross(n);
let a_t = (b.origin - a.origin).dot(n_b) / a.dir.dot(n_b);
let b_t = (a.origin - b.origin).dot(n_a) / b.dir.dot(n_a);
(a_t, b_t)
}
/// Returns the point where the ray intersects the plane.
/// Returns non-finite result of the ray and plane are parallel.
pub fn intersects_plane(&self, plane: crate::Plane3) -> Vec3 {
let (ro, rd) = (self.origin, self.dir);
let (pn, pd) = (plane.normal, plane.d);
// p = ro + t * rd
// p.dot(pn) + pd = 0
// (ro + t * rd).dot(pn) + pd = 0
// ro.dot(pn) + t * rd.dot(pn) + pd = 0
// t * rd.dot(pn) = -(ro.dot(pn) + pd)
// t = -(ro.dot(pn) + pd) / rd.dot(pn)
let t = -(ro.dot(pn) + pd) / rd.dot(pn);
ro + t * rd
// alternate implementation:
// let point = self.to_line().intersects_plane(plane);
// (point.truncate() / point.w).into()
}
// Returns the distance along the ray that is closest to the given point.
// The returned `t` can be negative.
#[inline]
pub fn closest_t_to_point(&self, point: Vec3) -> f32 {
self.dir.dot(point - self.origin)
}
/// Returns the point along the ray that is closest to the given point.
/// The returned point may be "behind" the ray origin.
#[inline]
pub fn closest_point_to_point(&self, point: Vec3) -> Vec3 {
self.origin + self.dir * self.dir.dot(point - self.origin)
}
}
impl core::ops::Mul<Ray3> for crate::IsoTransform {
type Output = Ray3;
fn mul(self, rhs: Ray3) -> Ray3 {
Ray3 {
origin: self.transform_point3(rhs.origin),
dir: self.transform_vector3(rhs.dir),
}
}
}
impl core::ops::Mul<Ray3> for crate::Conformal3 {
type Output = Ray3;
fn mul(self, rhs: Ray3) -> Ray3 {
Ray3 {
origin: self.transform_point3(rhs.origin),
dir: self.transform_vector3(rhs.dir),
}
}
}
impl core::ops::Mul<Ray3> for glam::Affine3A {
type Output = Ray3;
fn mul(self, rhs: Ray3) -> Ray3 {
Ray3 {
origin: self.transform_point3(rhs.origin),
dir: self.transform_vector3(rhs.dir).normalize(),
}
}
}
impl core::ops::Mul<Ray3> for glam::Mat4 {
type Output = Ray3;
fn mul(self, rhs: Ray3) -> Ray3 {
Ray3 {
origin: self.transform_point3(rhs.origin),
dir: self.transform_vector3(rhs.dir).normalize(),
}
}
}
#[cfg(not(target_arch = "spirv"))]
impl std::fmt::Debug for Ray3 {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.debug_struct("Ray3")
.field(
"origin",
&format!(
"[{:.3} {:.3} {:.3}]",
self.origin[0], self.origin[1], self.origin[2]
),
)
.field(
"dir",
&format!("[{:.2} {:.2} {:.2}]", self.dir[0], self.dir[1], self.dir[2]),
)
.finish()
}
}