Limited Collision events to one

CHANGELOG.md

@@ -3,7 +3,7 @@
   * Fixed bug causing the TM's unstuck logic to incorrectly remove the vehicles in some situations.
   * Fixed the extra data in Directx textures, so we need to copy row by row on Windows to remove extra bytes on images
   * Added empty actor
-  * The spectator will be used to load tiles and actor in Large Maps when no other actors with the rolename 'ego_vehicle' or 'hero' are present
+  * The spectator will be used to load tiles and actor in Large Maps when no other actors with the rolename 'ego_vehicle' or 'hero' are present. Added the `spectator_as_ego` to the `carla.WorldSettings()` to allow users to disable this behavior.
   * Fixed the import script, where could use any other TilesInfo.txt if the destination folder has many
   * Restored gamma value to 2.2 instead of 2.4
   * Added API function to avoid replaying the spectator
@@ -13,6 +13,7 @@
   * Added maps, vehicles, pedestrians and props catalogues to the documentation
   * Add keyword arguments for `carla.TrafficManager` Python API functions
   * Fixed bug causing the `FPixelReader::SavePixelsToDisk(PixelData, FilePath)` function to crash due to pixel array not set correctly.
+  * Collisions detected by the CollisionSensor no longer generate more than one event per frame.
 
 ## CARLA 0.9.14
 

Unreal/CarlaUE4/Plugins/Carla/Source/Carla/Sensor/CollisionSensor.cpp

@@ -10,6 +10,7 @@
 #include "Carla/Actor/ActorBlueprintFunctionLibrary.h"
 #include "Carla/Actor/ActorRegistry.h"
 #include "Carla/Game/CarlaEpisode.h"
+#include "Carla/Game/CarlaEngine.h"
 #include "Carla/Game/CarlaGameInstance.h"
 #include "Carla/Game/CarlaGameModeBase.h"
 
@@ -44,18 +45,34 @@ void ACollisionSensor::OnCollisionEvent(
     FVector NormalImpulse,
     const FHitResult &Hit)
 {
-  if ((Actor != nullptr) && (OtherActor != nullptr))
-  {
-    const auto &Episode = GetEpisode();
-    constexpr float TO_METERS = 1e-2;
-    NormalImpulse *= TO_METERS;
-    GetDataStream(*this).Send(
-        *this,
-        Episode.SerializeActor(Actor),
-        Episode.SerializeActor(OtherActor),
-        carla::geom::Vector3D{NormalImpulse.X, NormalImpulse.Y, NormalImpulse.Z});
-    // record the collision event
-    if (Episode.GetRecorder()->IsEnabled())
-      Episode.GetRecorder()->AddCollision(Actor, OtherActor);
+  if ((Actor == nullptr) || (OtherActor == nullptr)){
+    return;
   }
+
+  uint64_t CurrentFrame = FCarlaEngine::GetFrameCounter();
+  auto CollisionRegistry_ = CollisionRegistry;
+  for (auto & Collision: CollisionRegistry_){
+    if (std::get<0>(Collision) < CurrentFrame){
+      auto Index = std::find(CollisionRegistry.begin(), CollisionRegistry.end(), Collision);
+      CollisionRegistry.erase(Index);
+    }
+    else if ((std::get<0>(Collision) == CurrentFrame) && (std::get<1>(Collision) == Actor) && (std::get<2>(Collision) == OtherActor)){
+      return;
+    }
+  }
+
+  const auto &Episode = GetEpisode();
+  constexpr float TO_METERS = 1e-2;
+  NormalImpulse *= TO_METERS;
+  GetDataStream(*this).Send(
+      *this,
+      Episode.SerializeActor(Actor),
+      Episode.SerializeActor(OtherActor),
+      carla::geom::Vector3D{NormalImpulse.X, NormalImpulse.Y, NormalImpulse.Z});
+  // record the collision event
+  if (Episode.GetRecorder()->IsEnabled()){
+    Episode.GetRecorder()->AddCollision(Actor, OtherActor);
+  }
+
+  CollisionRegistry.push_back(std::make_tuple(CurrentFrame, Actor, OtherActor));
 }

Unreal/CarlaUE4/Plugins/Carla/Source/Carla/Sensor/CollisionSensor.h

@@ -36,4 +36,8 @@ private:
       AActor *OtherActor,
       FVector NormalImpulse,
       const FHitResult &Hit);
+
+  /// Registry that saves all collisions. Used to avoid sending the same collision more than once per frame,
+  /// as the collision sensor uses the PhysX substepping tick. Helps with sensor usage and stream overload.
+  std::vector<std::tuple<uint64_t, AActor*, AActor*>> CollisionRegistry;
 };