From 78dc64e05890a8888c711b6f8d84c26865a42cc5 Mon Sep 17 00:00:00 2001
From: Thierry Berger <contact@thierryberger.com>
Date: Mon, 14 Oct 2024 17:20:28 +0200
Subject: [PATCH] add an example to access a specific component of
 RapierContext

---
 bevy_rapier2d/examples/debugdump2.rs          |  2 +-
 .../{multi_world3.rs => multi_contexts3.rs}   |  0
 .../examples/rapier_context_component.rs      | 61 +++++++++++++++++++
 .../rapier_context_systemparam.rs             | 10 +--
 4 files changed, 68 insertions(+), 5 deletions(-)
 rename bevy_rapier3d/examples/{multi_world3.rs => multi_contexts3.rs} (100%)
 create mode 100644 bevy_rapier3d/examples/rapier_context_component.rs

diff --git a/bevy_rapier2d/examples/debugdump2.rs b/bevy_rapier2d/examples/debugdump2.rs
index 190a5079..4d133d91 100644
--- a/bevy_rapier2d/examples/debugdump2.rs
+++ b/bevy_rapier2d/examples/debugdump2.rs
@@ -1,6 +1,6 @@
 //! Example using bevy_mod_debugdump to output a graph of systems execution order.
 //! run with:
-//! `cargo run --example debugdump2 > dump.dot  && dot -Tsvg dump.dot > dump.svg`
+//! `cargo run --example debugdump2 > dump.dot && dot -Tsvg dump.dot > dump.svg`
 
 use bevy::prelude::*;
 use bevy_mod_debugdump::{schedule_graph, schedule_graph_dot};
diff --git a/bevy_rapier3d/examples/multi_world3.rs b/bevy_rapier3d/examples/multi_contexts3.rs
similarity index 100%
rename from bevy_rapier3d/examples/multi_world3.rs
rename to bevy_rapier3d/examples/multi_contexts3.rs
diff --git a/bevy_rapier3d/examples/rapier_context_component.rs b/bevy_rapier3d/examples/rapier_context_component.rs
new file mode 100644
index 00000000..156793a2
--- /dev/null
+++ b/bevy_rapier3d/examples/rapier_context_component.rs
@@ -0,0 +1,61 @@
+use bevy::prelude::*;
+use bevy_rapier3d::prelude::*;
+
+fn main() {
+    App::new()
+        .add_plugins((
+            DefaultPlugins,
+            RapierPhysicsPlugin::<NoUserData>::default(),
+            RapierDebugRenderPlugin::default(),
+        ))
+        .add_systems(Startup, (setup_physics, setup_graphics))
+        .add_systems(PostUpdate, display_nb_colliders)
+        .run();
+}
+
+/// Demonstrates how to access a more specific component of [`RapierContext`]
+fn display_nb_colliders(
+    query_context: Query<&RapierContextColliders, With<DefaultRapierContext>>,
+    mut exit: EventWriter<AppExit>,
+) {
+    let nb_colliders = query_context.single().colliders.len();
+    println!("There are {nb_colliders} colliders.");
+    if nb_colliders > 0 {
+        exit.send(AppExit::Success);
+    }
+}
+
+pub fn setup_physics(mut commands: Commands) {
+    /*
+     * Ground
+     */
+    let ground_size = 5.1;
+    let ground_height = 0.1;
+
+    let starting_y = -0.5 - ground_height;
+
+    commands.spawn((
+        TransformBundle::from(Transform::from_xyz(0.0, starting_y, 0.0)),
+        Collider::cuboid(ground_size, ground_height, ground_size),
+    ));
+
+    for _ in 0..3 {
+        /*
+         * Create the cubes
+         */
+
+        commands.spawn((
+            TransformBundle::default(),
+            RigidBody::Dynamic,
+            Collider::cuboid(0.5, 0.5, 0.5),
+        ));
+    }
+}
+
+fn setup_graphics(mut commands: Commands) {
+    commands.spawn(Camera3dBundle {
+        transform: Transform::from_xyz(0.0, 3.0, -10.0)
+            .looking_at(Vec3::new(0.0, 0.0, 0.0), Vec3::Y),
+        ..Default::default()
+    });
+}
diff --git a/src/plugin/context/systemparams/rapier_context_systemparam.rs b/src/plugin/context/systemparams/rapier_context_systemparam.rs
index 5386f4cd..91adcc3c 100644
--- a/src/plugin/context/systemparams/rapier_context_systemparam.rs
+++ b/src/plugin/context/systemparams/rapier_context_systemparam.rs
@@ -4,16 +4,18 @@ use bevy::prelude::*;
 use rapier::prelude::Real;
 
 pub(crate) const RAPIER_CONTEXT_EXPECT_ERROR: &str =
-    "RapierContextEntityLink.0 refers to an entity without RapierContext.";
+    "RapierContextEntityLink.0 refers to an entity missing components from RapierContextBundle.";
 
 use crate::{
     plugin::context::{
-        RapierContextColliders, RapierContextJoints, RapierQueryPipeline, RapierRigidBodySet,
+        DefaultRapierContext, RapierContextColliders, RapierContextJoints, RapierContextSimulation,
+        RapierQueryPipeline, RapierRigidBodySet,
     },
     prelude::QueryFilter,
 };
 
-use super::super::{DefaultRapierContext, RapierContextSimulation};
+#[cfg(doc)]
+use crate::prelude::RapierContextBundle;
 
 /// Utility [`SystemParam`] to easily access every required components of a [`RapierContext`] immutably.
 ///
@@ -58,7 +60,7 @@ impl<'w, 's, T: query::QueryFilter + 'static> ReadRapierContext<'w, 's, T> {
 /// A helper struct to avoid passing too many parameters to most rapier functions.
 /// This helps with reducing boilerplate, at the (small) price of maybe getting too much information from the ECS.
 ///
-/// Note: This is not a component, refer to [`ReadRapierContext`] or [`WriteRapierContext`]
+/// Note: This is not a component, refer to [`ReadRapierContext`], [`WriteRapierContext`], or [`RapierContextBundle`]
 #[derive(query::QueryData)]
 pub struct RapierContext<'a> {
     /// The Rapier context, containing all the state of the physics engine.