[Merged by Bors] - Fixed the frustum-sphere collision and added tests

crates/bevy_render/src/primitives/mod.rs

@@ -1,5 +1,5 @@
 use bevy_ecs::{component::Component, reflect::ReflectComponent};
-use bevy_math::{Mat4, Vec3, Vec3A, Vec4};
+use bevy_math::{Mat4, Vec3, Vec3A, Vec4, Vec4Swizzles};
 use bevy_reflect::Reflect;
 
 /// An Axis-Aligned Bounding Box
@@ -72,14 +72,26 @@ impl Sphere {
  }
 }
 
-/// A plane defined by a normal and distance value along the normal
+/// A plane defined by a normalized normal and distance value along the normal
 /// Any point p is in the plane if n.p = d
-/// For planes defining half-spaces such as for frusta, if n.p > d then p is on the positive side of the plane.
+/// For planes defining half-spaces such as for frusta, if n.p > d then p is on the positive side (inside) of the plane.
 #[derive(Clone, Copy, Debug, Default)]
 pub struct Plane {
  pub normal_d: Vec4,
 }
 
+impl Plane {
+ /// Constructs a `Plane` from a 4D vector whose first 3 components
+ /// are the normal and whose last component is d.
+ /// Ensures that the normal is normalized and d is scaled accordingly
+ /// so it represents the signed distance from the origin.
+ fn new(normal_d: Vec4) -> Self {
+ Self {
+ normal_d: normal_d * normal_d.xyz().length_recip(),
+ }
+ }
+}
+
 #[derive(Component, Clone, Copy, Debug, Default, Reflect)]
 #[reflect(Component)]
 pub struct Frustum {
@@ -102,17 +114,14 @@ impl Frustum {
  let mut planes = [Plane::default(); 6];
  for (i, plane) in planes.iter_mut().enumerate().take(5) {
  let row = view_projection.row(i / 2);
- plane.normal_d = if (i & 1) == 0 && i != 4 {
+ *plane = Plane::new(if (i & 1) == 0 && i != 4 {
  row3 + row
  } else {
  row3 - row
- }
- .normalize();
+ });
  }
  let far_center = *view_translation - far * *view_backward;
- planes[5].normal_d = view_backward
- .extend(-view_backward.dot(far_center))
- .normalize();
+ planes[5] = Plane::new(view_backward.extend(-view_backward.dot(far_center)));
  Self { planes }
  }
 
@@ -159,3 +168,160 @@ impl CubemapFrusta {
  self.frusta.iter_mut()
  }
 }
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ // A big, offset frustum
+ fn big_frustum() -> Frustum {
+ Frustum {
+ planes: [
+ Plane::new(Vec4::new(-0.9701, -0.2425, -0.0000, 7.7611)),
+ Plane::new(Vec4::new(-0.0000, 1.0000, -0.0000, 4.0000)),
+ Plane::new(Vec4::new(-0.0000, -0.2425, -0.9701, 2.9104)),
+ Plane::new(Vec4::new(-0.0000, -1.0000, -0.0000, 4.0000)),
+ Plane::new(Vec4::new(-0.0000, -0.2425, 0.9701, 2.9104)),
+ Plane::new(Vec4::new(0.9701, -0.2425, -0.0000, -1.9403)),
+ ],
+ }
+ }
+
+ #[test]
+ fn intersects_sphere_big_frustum_outside() {
+ // Sphere outside frustum
+ let frustum = big_frustum();
+ let sphere = Sphere {
+ center: Vec3::new(0.9167, 0.0000, 0.0000),
+ radius: 0.7500,
+ };
+ assert!(!frustum.intersects_sphere(&sphere));
+ }
+
+ #[test]
+ fn intersects_sphere_big_frustum_intersect() {
+ // Sphere intersects frustum boundary
+ let frustum = big_frustum();
+ let sphere = Sphere {
+ center: Vec3::new(7.9288, 0.0000, 2.9728),
+ radius: 2.0000,
+ };
+ assert!(frustum.intersects_sphere(&sphere));
+ }
+
+ // A frustum
+ fn frustum() -> Frustum {
+ Frustum {
+ planes: [
+ Plane::new(Vec4::new(-0.9701, -0.2425, -0.0000, 0.7276)),
+ Plane::new(Vec4::new(-0.0000, 1.0000, -0.0000, 1.0000)),
+ Plane::new(Vec4::new(-0.0000, -0.2425, -0.9701, 0.7276)),
+ Plane::new(Vec4::new(-0.0000, -1.0000, -0.0000, 1.0000)),
+ Plane::new(Vec4::new(-0.0000, -0.2425, 0.9701, 0.7276)),
+ Plane::new(Vec4::new(0.9701, -0.2425, -0.0000, 0.7276)),
+ ],
+ }
+ }
+
+ #[test]
+ fn intersects_sphere_frustum_surrounding() {
+ // Sphere surrounds frustum
+ let frustum = frustum();
+ let sphere = Sphere {
+ center: Vec3::new(0.0000, 0.0000, 0.0000),
+ radius: 3.0000,
+ };
+ assert!(frustum.intersects_sphere(&sphere));
+ }
+
+ #[test]
+ fn intersects_sphere_frustum_contained() {
+ // Sphere is contained in frustum
+ let frustum = frustum();
+ let sphere = Sphere {
+ center: Vec3::new(0.0000, 0.0000, 0.0000),
+ radius: 0.7000,
+ };
+ assert!(frustum.intersects_sphere(&sphere));
+ }
+
+ #[test]
+ fn intersects_sphere_frustum_intersects_plane() {
+ // Sphere intersects a plane
+ let frustum = frustum();
+ let sphere = Sphere {
+ center: Vec3::new(0.0000, 0.0000, 0.9695),
+ radius: 0.7000,
+ };
+ assert!(frustum.intersects_sphere(&sphere));
+ }
+
+ #[test]
+ fn intersects_sphere_frustum_intersects_2_planes() {
+ // Sphere intersects 2 planes
+ let frustum = frustum();
+ let sphere = Sphere {
+ center: Vec3::new(1.2037, 0.0000, 0.9695),
+ radius: 0.7000,
+ };
+ assert!(frustum.intersects_sphere(&sphere));
+ }
+
+ #[test]
+ fn intersects_sphere_frustum_intersects_3_planes() {
+ // Sphere intersects 3 planes
+ let frustum = frustum();
+ let sphere = Sphere {
+ center: Vec3::new(1.2037, -1.0988, 0.9695),
+ radius: 0.7000,
+ };
+ assert!(frustum.intersects_sphere(&sphere));
+ }
+
+ #[test]
+ fn intersects_sphere_frustum_dodges_1_plane() {
+ // Sphere avoids intersecting the frustum by 1 plane
+ let frustum = frustum();
+ let sphere = Sphere {
+ center: Vec3::new(-1.7020, 0.0000, 0.0000),
+ radius: 0.7000,
+ };
+ assert!(!frustum.intersects_sphere(&sphere));
+ }
+
+ // A long frustum.
+ fn long_frustum() -> Frustum {
+ Frustum {
+ planes: [
+ Plane::new(Vec4::new(-0.9998, -0.0222, -0.0000, -1.9543)),
+ Plane::new(Vec4::new(-0.0000, 1.0000, -0.0000, 45.1249)),
+ Plane::new(Vec4::new(-0.0000, -0.0168, -0.9999, 2.2718)),
+ Plane::new(Vec4::new(-0.0000, -1.0000, -0.0000, 45.1249)),
+ Plane::new(Vec4::new(-0.0000, -0.0168, 0.9999, 2.2718)),
+ Plane::new(Vec4::new(0.9998, -0.0222, -0.0000, 7.9528)),
+ ],
+ }
+ }
+
+ #[test]
+ fn intersects_sphere_long_frustum_outside() {
+ // Sphere outside frustum
+ let frustum = long_frustum();
+ let sphere = Sphere {
+ center: Vec3::new(-4.4889, 46.9021, 0.0000),
+ radius: 0.7500,
+ };
+ assert!(!frustum.intersects_sphere(&sphere));
+ }
+
+ #[test]
+ fn intersects_sphere_long_frustum_intersect() {
+ // Sphere intersects frustum boundary
+ let frustum = long_frustum();
+ let sphere = Sphere {
+ center: Vec3::new(-4.9957, 0.0000, -0.7396),
+ radius: 4.4094,
+ };
+ assert!(frustum.intersects_sphere(&sphere));
+ }
+}