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Add methods intersect_plane and get_point to Ray (bevyengine#6179)
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Co-authored-by: devil-ira <justthecooldude@gmail.com>
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2 people authored and ItsDoot committed Feb 1, 2023
1 parent 56a6b3e commit 2cfcb73
Showing 1 changed file with 54 additions and 1 deletion.
55 changes: 54 additions & 1 deletion crates/bevy_math/src/ray.rs
Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,59 @@ use crate::Vec3;
pub struct Ray {
/// The origin of the ray.
pub origin: Vec3,
/// The direction of the ray.
/// A normalized vector representing the direction of the ray.
pub direction: Vec3,
}

impl Ray {
/// Returns the distance to the plane if the ray intersects it.
#[inline]
pub fn intersect_plane(&self, plane_origin: Vec3, plane_normal: Vec3) -> Option<f32> {
let denominator = plane_normal.dot(self.direction);
if denominator.abs() > f32::EPSILON {
let distance = (plane_origin - self.origin).dot(plane_normal) / denominator;
if distance >= f32::EPSILON {
return Some(distance);
}
}
None
}

/// Retrieve a point at the given distance along the ray.
#[inline]
pub fn get_point(&self, distance: f32) -> Vec3 {
self.origin + self.direction * distance
}
}

#[cfg(test)]
mod test {
use super::*;

#[test]
fn intersects_plane() {
let ray = Ray {
origin: Vec3::ZERO,
direction: Vec3::Z,
};

// Orthogonal, and test that plane_normal direction doesn't matter
assert_eq!(Some(1.), ray.intersect_plane(Vec3::Z, Vec3::Z));
assert_eq!(Some(1.), ray.intersect_plane(Vec3::Z, Vec3::NEG_Z));
assert_eq!(None, ray.intersect_plane(Vec3::NEG_Z, Vec3::Z));
assert_eq!(None, ray.intersect_plane(Vec3::NEG_Z, Vec3::NEG_Z));

// Diagonal
assert_eq!(Some(1.), ray.intersect_plane(Vec3::Z, Vec3::ONE));
assert_eq!(None, ray.intersect_plane(Vec3::NEG_Z, Vec3::ONE));

// Parralel
assert_eq!(None, ray.intersect_plane(Vec3::X, Vec3::X));

// Parralel with simulated rounding error
assert_eq!(
None,
ray.intersect_plane(Vec3::X, Vec3::X + Vec3::Z * f32::EPSILON)
);
}
}

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