From 24947d12a2440b8a5580823e026cb0a259c68553 Mon Sep 17 00:00:00 2001
From: Travis Lange <travislange12@gmail.com>
Date: Sat, 11 Nov 2023 19:06:20 -0500
Subject: [PATCH] added support for active collision events regardless if
 started was called

---
 src/geometry/contact_pair.rs  | 30 ++++++++++++++++++++++++++++++
 src/geometry/mod.rs           | 11 +++++++----
 src/geometry/narrow_phase.rs  | 11 +++++++++++
 src/pipeline/event_handler.rs |  4 ++++
 4 files changed, 52 insertions(+), 4 deletions(-)

diff --git a/src/geometry/contact_pair.rs b/src/geometry/contact_pair.rs
index 3bef40da2..250d26de7 100644
--- a/src/geometry/contact_pair.rs
+++ b/src/geometry/contact_pair.rs
@@ -101,6 +101,22 @@ impl IntersectionPair {
             None,
         );
     }
+
+    pub(crate) fn emit_active_event(
+        &mut self,
+        bodies: &RigidBodySet,
+        colliders: &ColliderSet,
+        collider1: ColliderHandle,
+        collider2: ColliderHandle,
+        events: &dyn EventHandler,
+    ) {
+        events.handle_collision_event(
+            bodies,
+            colliders,
+            CollisionEvent::Active(collider1, collider2, CollisionEventFlags::SENSOR),
+            None,
+        );
+    }
 }
 
 #[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
@@ -231,6 +247,20 @@ impl ContactPair {
             Some(self),
         );
     }
+
+    pub(crate) fn emit_active_event(
+        &mut self,
+        bodies: &RigidBodySet,
+        colliders: &ColliderSet,
+        events: &dyn EventHandler,
+    ) {
+        events.handle_collision_event(
+            bodies,
+            colliders,
+            CollisionEvent::Active(self.collider1, self.collider2, CollisionEventFlags::empty()),
+            Some(self),
+        );
+    }
 }
 
 #[derive(Clone, Debug)]
diff --git a/src/geometry/mod.rs b/src/geometry/mod.rs
index a91c4b90c..3ce5c46e0 100644
--- a/src/geometry/mod.rs
+++ b/src/geometry/mod.rs
@@ -76,6 +76,9 @@ pub enum CollisionEvent {
     Started(ColliderHandle, ColliderHandle, CollisionEventFlags),
     /// Event occurring when two colliders stop colliding.
     Stopped(ColliderHandle, ColliderHandle, CollisionEventFlags),
+    /// Event occurring when two colliders are actively colliding.
+    /// Even after `CollisionEvent::Started` has already been called.
+    Active(ColliderHandle, ColliderHandle, CollisionEventFlags),
 }
 
 impl CollisionEvent {
@@ -92,21 +95,21 @@ impl CollisionEvent {
     /// The handle of the first collider involved in this collision event.
     pub fn collider1(self) -> ColliderHandle {
         match self {
-            Self::Started(h, _, _) | Self::Stopped(h, _, _) => h,
+            Self::Started(h, _, _) | Self::Stopped(h, _, _) | Self::Active(h, _, _) => h,
         }
     }
 
     /// The handle of the second collider involved in this collision event.
     pub fn collider2(self) -> ColliderHandle {
         match self {
-            Self::Started(_, h, _) | Self::Stopped(_, h, _) => h,
+            Self::Started(_, h, _) | Self::Stopped(_, h, _) | Self::Active(_, h, _) => h,
         }
     }
 
     /// Was at least one of the colliders involved in the collision a sensor?
     pub fn sensor(self) -> bool {
         match self {
-            Self::Started(_, _, f) | Self::Stopped(_, _, f) => {
+            Self::Started(_, _, f) | Self::Stopped(_, _, f) | Self::Active(_, _, f) => {
                 f.contains(CollisionEventFlags::SENSOR)
             }
         }
@@ -115,7 +118,7 @@ impl CollisionEvent {
     /// Was at least one of the colliders involved in the collision removed?
     pub fn removed(self) -> bool {
         match self {
-            Self::Started(_, _, f) | Self::Stopped(_, _, f) => {
+            Self::Started(_, _, f) | Self::Stopped(_, _, f) | Self::Active(_, _, f) => {
                 f.contains(CollisionEventFlags::REMOVED)
             }
         }
diff --git a/src/geometry/narrow_phase.rs b/src/geometry/narrow_phase.rs
index 4500284db..3b87940c8 100644
--- a/src/geometry/narrow_phase.rs
+++ b/src/geometry/narrow_phase.rs
@@ -762,6 +762,11 @@ impl NarrowPhase {
 
             let active_events = co1.flags.active_events | co2.flags.active_events;
 
+            if had_intersection && active_events.contains(ActiveEvents::ACTIVE_COLLISION_EVENTS) {
+                edge.weight
+                    .emit_active_event(bodies, colliders, handle1, handle2, events);
+            }
+
             if active_events.contains(ActiveEvents::COLLISION_EVENTS)
                 && had_intersection != edge.weight.intersecting
             {
@@ -993,6 +998,12 @@ impl NarrowPhase {
 
             let active_events = co1.flags.active_events | co2.flags.active_events;
 
+            if pair.has_any_active_contact
+                && active_events.contains(ActiveEvents::ACTIVE_COLLISION_EVENTS)
+            {
+                pair.emit_active_event(bodies, colliders, events);
+            }
+
             if pair.has_any_active_contact != had_any_active_contact {
                 if active_events.contains(ActiveEvents::COLLISION_EVENTS) {
                     if pair.has_any_active_contact {
diff --git a/src/pipeline/event_handler.rs b/src/pipeline/event_handler.rs
index 7957ccf3e..59081865c 100644
--- a/src/pipeline/event_handler.rs
+++ b/src/pipeline/event_handler.rs
@@ -13,6 +13,10 @@ bitflags::bitflags! {
         /// If set, Rapier will call `EventHandler::handle_contact_force_event`
         /// whenever relevant for this collider.
         const CONTACT_FORCE_EVENTS = 0b0010;
+        /// If set, Rapier will call `EventHandler::handle_collision_event`
+        /// whenever relevant for this collider. Even after `CollisionEvent::Started`
+        /// has already been called.
+        const ACTIVE_COLLISION_EVENTS = 0b0100;
     }
 }