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use bevy::{
ecs::system::{lifetimeless::Read, SystemParam},
prelude::*,
render::primitives::Aabb,
sprite::Mesh2dHandle,
utils::FloatOrd,
};
use crate::{
ray_intersection_over_mesh, Backfaces, IntersectionData, NoBackfaceCulling, Ray3d,
SimplifiedMesh,
};
/// How a raycast should handle visibility
#[derive(Clone, Copy, Reflect)]
pub enum RaycastVisibility {
/// Completely ignore visibility checks. Hidden items can still be raycasted against.
Ignore,
/// Only raycast against entities that are visible in the hierarchy; see [`Visibility`].
MustBeVisible,
/// Only raycast against entities that are visible in the hierarchy and visible to a camera or
/// light; see [`Visibility`].
MustBeVisibleAndInView,
}
/// Settings for a raycast.
#[derive(Clone, Reflect)]
pub struct RaycastSettings<'a> {
/// Determines how raycasting should consider entity visibility.
pub visibility: RaycastVisibility,
/// A filtering function that is applied to every entity that is raycasted. Only entities that
/// return `true` will be considered.
pub filter: &'a dyn Fn(Entity) -> bool,
/// A function that is run every time a hit is found. Raycasting will continue to check for hits
/// along the ray as long as this returns false.
pub early_exit_test: &'a dyn Fn(Entity) -> bool,
}
impl<'a> RaycastSettings<'a> {
/// Set the filter to apply to the raycast.
pub fn with_filter(mut self, filter: &'a impl Fn(Entity) -> bool) -> Self {
self.filter = filter;
self
}
/// Set the early exit test to apply to the raycast.
pub fn with_early_exit_test(mut self, early_exit_test: &'a impl Fn(Entity) -> bool) -> Self {
self.early_exit_test = early_exit_test;
self
}
/// This raycast should exit as soon as the nearest hit is found.
pub fn always_early_exit(self) -> Self {
self.with_early_exit_test(&|_| true)
}
/// This raycast should check all entities whose AABB intersects the ray and return all hits.
pub fn never_early_exit(self) -> Self {
self.with_early_exit_test(&|_| false)
}
}
impl<'a> Default for RaycastSettings<'a> {
fn default() -> Self {
Self {
visibility: RaycastVisibility::MustBeVisibleAndInView,
filter: &|_| true,
early_exit_test: &|_| true,
}
}
}
/// A [`SystemParam`] that allows you to raycast into the world.
#[derive(SystemParam)]
pub struct Raycast<'w, 's> {
pub meshes: Res<'w, Assets<Mesh>>,
pub hits: Local<'s, Vec<(FloatOrd, (Entity, IntersectionData))>>,
pub output: Local<'s, Vec<(Entity, IntersectionData)>>,
pub culled_list: Local<'s, Vec<(FloatOrd, Entity)>>,
pub culling_query: Query<
'w,
's,
(
Read<ComputedVisibility>,
Read<Aabb>,
Read<GlobalTransform>,
Entity,
),
With<Handle<Mesh>>,
>,
pub mesh_query: Query<
'w,
's,
(
Read<Handle<Mesh>>,
Option<Read<SimplifiedMesh>>,
Option<Read<NoBackfaceCulling>>,
Read<GlobalTransform>,
),
>,
#[cfg(feature = "2d")]
pub mesh2d_query: Query<
'w,
's,
(
Read<Mesh2dHandle>,
Option<Read<SimplifiedMesh>>,
Read<GlobalTransform>,
),
>,
}
impl<'w, 's> Raycast<'w, 's> {
/// Casts the `ray` into the world and returns a sorted list of intersections, nearest first.
pub fn cast_ray(
&mut self,
ray: Ray3d,
settings: &RaycastSettings,
) -> &[(Entity, IntersectionData)] {
let ray_cull = info_span!("ray culling");
let ray_cull_guard = ray_cull.enter();
self.hits.clear();
self.culled_list.clear();
self.output.clear();
// Check all entities to see if the ray intersects the AABB, use this to build a short list
// of entities that are in the path of the ray.
let (aabb_hits_tx, aabb_hits_rx) = crossbeam_channel::unbounded::<(FloatOrd, Entity)>();
let visibility_setting = settings.visibility;
self.culling_query
.par_iter()
.for_each(|(visibility, aabb, transform, entity)| {
let should_raycast = match visibility_setting {
RaycastVisibility::Ignore => true,
RaycastVisibility::MustBeVisible => visibility.is_visible_in_hierarchy(),
RaycastVisibility::MustBeVisibleAndInView => visibility.is_visible_in_view(),
};
if should_raycast {
if let Some([near, _]) = ray
.intersects_aabb(aabb, &transform.compute_matrix())
.filter(|[_, far]| *far >= 0.0)
{
aabb_hits_tx.send((FloatOrd(near), entity)).ok();
}
}
});
*self.culled_list = aabb_hits_rx.try_iter().collect();
self.culled_list.sort_by_key(|(aabb_near, _)| *aabb_near);
drop(ray_cull_guard);
let mut nearest_blocking_hit = FloatOrd(f32::INFINITY);
let raycast_guard = info_span!("raycast");
self.culled_list
.iter()
.filter(|(_, entity)| (settings.filter)(*entity))
.for_each(|(aabb_near, entity)| {
let mut raycast_mesh =
|mesh_handle: &Handle<Mesh>,
simplified_mesh: Option<&SimplifiedMesh>,
no_backface_culling: Option<&NoBackfaceCulling>,
transform: &GlobalTransform| {
// Is it even possible the mesh could be closer than the current best?
if *aabb_near > nearest_blocking_hit {
return;
}
// Does the mesh handle resolve?
let mesh_handle = simplified_mesh.map(|m| &m.mesh).unwrap_or(mesh_handle);
let Some(mesh) = self.meshes.get(mesh_handle) else {
return
};
let _raycast_guard = raycast_guard.enter();
let backfaces = match no_backface_culling {
Some(_) => Backfaces::Include,
None => Backfaces::Cull,
};
let transform = transform.compute_matrix();
let intersection =
ray_intersection_over_mesh(mesh, &transform, &ray, backfaces);
if let Some(intersection) = intersection {
let distance = FloatOrd(intersection.distance());
if (settings.early_exit_test)(*entity)
&& distance < nearest_blocking_hit
{
// The reason we don't just return here is because right now we are
// going through the AABBs in order, but that doesn't mean that an
// AABB that starts further away cant end up with a closer hit than
// an AABB that starts closer. We need to keep checking AABBs that
// could possibly contain a nearer hit.
nearest_blocking_hit = distance.min(nearest_blocking_hit);
}
self.hits.push((distance, (*entity, intersection)));
};
};
if let Ok((mesh, simp_mesh, culling, transform)) = self.mesh_query.get(*entity) {
raycast_mesh(mesh, simp_mesh, culling, transform);
}
#[cfg(feature = "2d")]
if let Ok((mesh, simp_mesh, transform)) = self.mesh2d_query.get(*entity) {
raycast_mesh(&mesh.0, simp_mesh, Some(&NoBackfaceCulling), transform);
}
});
self.hits.retain(|(dist, _)| *dist <= nearest_blocking_hit);
self.hits.sort_by_key(|(k, _)| *k);
let hits = self.hits.iter().map(|(_, (e, i))| (*e, i.to_owned()));
*self.output = hits.collect();
self.output.as_ref()
}
}