From 0e3a84a06ba252bcb06d86cfc49ae4718a9524e0 Mon Sep 17 00:00:00 2001
From: Diren D Bharwani <diren.bharwani@gmail.com>
Date: Wed, 1 Mar 2023 04:34:20 +0800
Subject: [PATCH] Fixed bug where changing scenes would not clear drawn
 colliders

---
 .../System/SHPhysicsDebugDrawSystem.cpp       | 20 ++++++++++++++++---
 .../Physics/System/SHPhysicsDebugDrawSystem.h | 15 ++++++++++----
 2 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/SHADE_Engine/src/Physics/System/SHPhysicsDebugDrawSystem.cpp b/SHADE_Engine/src/Physics/System/SHPhysicsDebugDrawSystem.cpp
index ae25216f..ad99c363 100644
--- a/SHADE_Engine/src/Physics/System/SHPhysicsDebugDrawSystem.cpp
+++ b/SHADE_Engine/src/Physics/System/SHPhysicsDebugDrawSystem.cpp
@@ -38,6 +38,9 @@ namespace SHADE
   : flags { 0 }
   {
     collidersToDraw.clear();
+
+    eventFunctions[0] = { &SHPhysicsDebugDrawSystem::onColliderDraw , SH_PHYSICS_COLLIDER_DRAW_EVENT };
+    eventFunctions[1] = { &SHPhysicsDebugDrawSystem::onSceneExit    , SH_SCENE_EXIT_PRE  };
   }
 
   /*-----------------------------------------------------------------------------------*/
@@ -78,10 +81,13 @@ namespace SHADE
     SystemFamily::GetID<SHPhysicsDebugDrawSystem>();
 
     // Register collider draw event
-    const std::shared_ptr EVENT_RECEIVER      = std::make_shared<SHEventReceiverSpec<SHPhysicsDebugDrawSystem>>(this, &SHPhysicsDebugDrawSystem::onColliderDraw);
-    const ReceiverPtr     EVENT_RECEIVER_PTR  = std::dynamic_pointer_cast<SHEventReceiver>(EVENT_RECEIVER);
+    for (int i = 0; i < NUM_EVENT_FUNCTIONS; ++i)
+    {
+      const std::shared_ptr EVENT_RECEIVER      = std::make_shared<SHEventReceiverSpec<SHPhysicsDebugDrawSystem>>(this, eventFunctions[i].first);
+      const ReceiverPtr     EVENT_RECEIVER_PTR  = std::dynamic_pointer_cast<SHEventReceiver>(EVENT_RECEIVER);
 
-    SHEventManager::SubscribeTo(SH_PHYSICS_COLLIDER_DRAW_EVENT, EVENT_RECEIVER_PTR);
+      SHEventManager::SubscribeTo(eventFunctions[i].second, EVENT_RECEIVER_PTR);
+    }
   }
 
   void SHPhysicsDebugDrawSystem::Exit()
@@ -122,6 +128,14 @@ namespace SHADE
     return onColliderDrawEvent.get()->handle;
   }
 
+  SHEventHandle SHPhysicsDebugDrawSystem::onSceneExit(SHEventPtr onSceneExitEvent)
+  {
+    // Empty list of colliders to draw
+    collidersToDraw.clear();
+    return onSceneExitEvent.get()->handle;
+  }
+
+
   void SHPhysicsDebugDrawSystem::drawCollider(SHDebugDrawSystem* debugDrawSystem, const SHCollider& collider) noexcept
   {
     for (const auto* SHAPE : collider.GetCollisionShapes())
diff --git a/SHADE_Engine/src/Physics/System/SHPhysicsDebugDrawSystem.h b/SHADE_Engine/src/Physics/System/SHPhysicsDebugDrawSystem.h
index 336dff0c..83f96377 100644
--- a/SHADE_Engine/src/Physics/System/SHPhysicsDebugDrawSystem.h
+++ b/SHADE_Engine/src/Physics/System/SHPhysicsDebugDrawSystem.h
@@ -89,6 +89,8 @@ namespace SHADE
     /* Type Definitions                                                                */
     /*---------------------------------------------------------------------------------*/
 
+    using EventFunctionPair = std::pair<SHEventHandle(SHPhysicsDebugDrawSystem::*)(SHEventPtr), SHEventIdentifier>;
+
     union DebugDrawInfo
     {
       struct Contact
@@ -123,20 +125,25 @@ namespace SHADE
     /* Data Members                                                                    */
     /*---------------------------------------------------------------------------------*/
 
-    static constexpr uint8_t ACTIVE_FLAG = 0x01;
+    static constexpr uint8_t  ACTIVE_FLAG = 0x01;
+    static constexpr int      NUM_EVENT_FUNCTIONS = 4;
 
-    static const SHColour DEBUG_DRAW_COLOURS[static_cast<int>(Colours::COUNT)];
+    static const SHColour     DEBUG_DRAW_COLOURS[static_cast<int>(Colours::COUNT)];
+
+    // Event function container for cleanly registering to events
+    EventFunctionPair         eventFunctions[NUM_EVENT_FUNCTIONS];
 
     // 0 0 0 drawBroadphase drawRaycasts drawContacts drawAllColliders debugDrawActive
-    uint8_t   flags;
+    uint8_t                   flags;
 
-    Colliders collidersToDraw;
+    Colliders                 collidersToDraw;
 
     /*---------------------------------------------------------------------------------*/
     /* Member Functions                                                                */
     /*---------------------------------------------------------------------------------*/
 
     SHEventHandle onColliderDraw(SHEventPtr onColliderDrawEvent);
+    SHEventHandle onSceneExit   (SHEventPtr onSceneExitEvent);
 
     static void   drawCollider  (SHDebugDrawSystem* debugDrawSystem, const SHCollider& collider)                noexcept;
     static void   drawRaycast   (SHDebugDrawSystem* debugDrawSystem, const DebugDrawInfo::Raycast& raycastInfo) noexcept;