From f92ec30e1b7ffcf849b6739f7f963234a2e5fce5 Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Thu, 26 Mar 2026 09:26:42 +0100
Subject: [PATCH] Fix crash when using convex mesh collider with negative scale

#3853
---
 Source/Engine/Physics/Colliders/Collider.cpp  | 31 ++++++++++++-------
 .../Physics/PhysX/PhysicsBackendPhysX.cpp     |  7 +++--
 2 files changed, 25 insertions(+), 13 deletions(-)

diff --git a/Source/Engine/Physics/Colliders/Collider.cpp b/Source/Engine/Physics/Colliders/Collider.cpp
index 96bd9c7ae..28588e2a6 100644
--- a/Source/Engine/Physics/Colliders/Collider.cpp
+++ b/Source/Engine/Physics/Colliders/Collider.cpp
@@ -209,6 +209,13 @@ void Collider::CreateShape()
     // Create shape
     const bool isTrigger = _isTrigger && CanBeTrigger();
     _shape = PhysicsBackend::CreateShape(this, shape, Material, IsActiveInHierarchy(), isTrigger);
+    if (!_shape)
+    {
+        LOG(Error, "Failed to create physics shape for actor '{}'", GetNamePath());
+        if (shape.Type == CollisionShape::Types::ConvexMesh && Float3(shape.ConvexMesh.Scale).MinValue() <= 0)
+            LOG(Warning, "Convex Mesh colliders cannot have negative scale");
+        return;
+    }
     PhysicsBackend::SetShapeContactOffset(_shape, _contactOffset);
     UpdateLayerBits();
 }
@@ -293,18 +300,20 @@ void Collider::BeginPlay(SceneBeginData* data)
     if (_shape == nullptr)
     {
         CreateShape();
-
-        // Check if parent is a rigidbody
-        const auto rigidBody = dynamic_cast<RigidBody*>(GetParent());
-        if (rigidBody && CanAttach(rigidBody))
+        if (_shape)
         {
-            // Attach to the rigidbody
-            Attach(rigidBody);
-        }
-        else
-        {
-            // Be a static collider
-            CreateStaticActor();
+            // Check if parent is a rigidbody
+            const auto rigidBody = dynamic_cast<RigidBody*>(GetParent());
+            if (rigidBody && CanAttach(rigidBody))
+            {
+                // Attach to the rigidbody
+                Attach(rigidBody);
+            }
+            else
+            {
+                // Be a static collider
+                CreateStaticActor();
+            }
         }
     }
 
diff --git a/Source/Engine/Physics/PhysX/PhysicsBackendPhysX.cpp b/Source/Engine/Physics/PhysX/PhysicsBackendPhysX.cpp
index 02e23d890..5aba5343b 100644
--- a/Source/Engine/Physics/PhysX/PhysicsBackendPhysX.cpp
+++ b/Source/Engine/Physics/PhysX/PhysicsBackendPhysX.cpp
@@ -2653,10 +2653,13 @@ void* PhysicsBackend::CreateShape(PhysicsColliderActor* collider, const Collisio
     PxGeometryHolder geometryPhysX;
     GetShapeGeometry(geometry, geometryPhysX);
     PxShape* shapePhysX = PhysX->createShape(geometryPhysX.any(), materialsPhysX.Get(), materialsPhysX.Count(), true, shapeFlags);
-    shapePhysX->userData = collider;
+    if (shapePhysX)
+    {
+        shapePhysX->userData = collider;
 #if PHYSX_DEBUG_NAMING
-    shapePhysX->setName("Shape");
+        shapePhysX->setName("Shape");
 #endif
+    }
     return shapePhysX;
 }