From 4e7da2cf4e7105f6b18e3081a1fa114bfb0e83b4 Mon Sep 17 00:00:00 2001
From: Joona Aalto <jondolf.dev@gmail.com>
Date: Sat, 2 Dec 2023 15:53:35 +0200
Subject: [PATCH] Add `Ray2d` and `Ray3d` primitives

---
 crates/bevy_math/src/primitives/dim2.rs | 35 +++++++++++++++++++++-
 crates/bevy_math/src/primitives/dim3.rs | 40 ++++++++++++++++++++++++-
 2 files changed, 73 insertions(+), 2 deletions(-)

diff --git a/crates/bevy_math/src/primitives/dim2.rs b/crates/bevy_math/src/primitives/dim2.rs
index 35e5363dc6acd..631ff7421c3e5 100644
--- a/crates/bevy_math/src/primitives/dim2.rs
+++ b/crates/bevy_math/src/primitives/dim2.rs
@@ -2,7 +2,7 @@ use super::{Primitive2d, WindingOrder};
 use crate::Vec2;
 
 /// A normalized vector pointing in a direction in 2D space
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Copy, Debug, PartialEq)]
 pub struct Direction2d(Vec2);
 
 impl From<Vec2> for Direction2d {
@@ -63,6 +63,32 @@ pub struct Plane2d {
 }
 impl Primitive2d for Plane2d {}
 
+/// An infinite half-line starting at `origin` and going in `direction` in 2D space.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct Ray2d {
+    /// The origin of the ray.
+    pub origin: Vec2,
+    /// The direction of the ray.
+    pub direction: Direction2d,
+}
+
+impl Ray2d {
+    /// Create a new `Ray2d` from a given origin and direction
+    #[inline]
+    pub fn new(origin: Vec2, direction: Vec2) -> Self {
+        Self {
+            origin,
+            direction: direction.into(),
+        }
+    }
+
+    /// Get a point at a given distance along the ray
+    #[inline]
+    pub fn get_point(&self, distance: f32) -> Vec2 {
+        self.origin + *self.direction * distance
+    }
+}
+
 /// An infinite line along a direction in 2D space.
 ///
 /// For a finite line: [`Segment2d`]
@@ -323,6 +349,13 @@ impl RegularPolygon {
 mod tests {
     use super::*;
 
+    #[test]
+    fn ray_math() {
+        let ray = Ray2d::new(Vec2::ZERO, Vec2::Y * 10.0);
+        assert_eq!(*ray.direction, Vec2::Y, "ray direction is not normalized");
+        assert_eq!(ray.get_point(2.0), Vec2::Y * 2.0);
+    }
+
     #[test]
     fn triangle_winding_order() {
         let mut cw_triangle = Triangle2d::new(
diff --git a/crates/bevy_math/src/primitives/dim3.rs b/crates/bevy_math/src/primitives/dim3.rs
index 891f51558fd3b..1529044af5e9a 100644
--- a/crates/bevy_math/src/primitives/dim3.rs
+++ b/crates/bevy_math/src/primitives/dim3.rs
@@ -2,7 +2,7 @@ use super::Primitive3d;
 use crate::Vec3;
 
 /// A normalized vector pointing in a direction in 3D space
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Copy, Debug, PartialEq)]
 pub struct Direction3d(Vec3);
 
 impl From<Vec3> for Direction3d {
@@ -43,6 +43,32 @@ pub struct Plane3d {
 }
 impl Primitive3d for Plane3d {}
 
+/// An infinite half-line starting at `origin` and going in `direction` in 3D space.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct Ray3d {
+    /// The origin of the ray.
+    pub origin: Vec3,
+    /// The direction of the ray.
+    pub direction: Direction3d,
+}
+
+impl Ray3d {
+    /// Create a new `Ray3d` from a given origin and direction
+    #[inline]
+    pub fn new(origin: Vec3, direction: Vec3) -> Self {
+        Self {
+            origin,
+            direction: direction.into(),
+        }
+    }
+
+    /// Get a point at a given distance along the ray
+    #[inline]
+    pub fn get_point(&self, distance: f32) -> Vec3 {
+        self.origin + *self.direction * distance
+    }
+}
+
 /// An infinite line along a direction in 3D space.
 ///
 /// For a finite line: [`Segment3d`]
@@ -331,3 +357,15 @@ impl Torus {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn ray_math() {
+        let ray = Ray3d::new(Vec3::ZERO, Vec3::Z * 10.0);
+        assert_eq!(*ray.direction, Vec3::Z, "ray direction is not normalized");
+        assert_eq!(ray.get_point(2.0), Vec3::Z * 2.0);
+    }
+}