ERROR: Collider copied but shape is nullptr! Jolt Physics

[Sekaus]

I'm trying to use Jolt Physics in my C++ game but run into an issue at runtime.
It keeps printing out this error message:

[ERROR] Collider copied but shape is nullptr!

I have:

• Setup Jolt Physics using vcpkg
• Compiled the package using cmake
• linked the compiled library (Jolt.lib) right

I have noticed that mShapePtr in JPH::BoxShapeSettings settings in PhysicsEngine::addBody is set but not mShape but I don't know why...

Is there something I miss?

Here is some code from my project:

#include <iostream>

// --- Minimal Collider implementation ---
namespace BlockyBuild {

    enum ColliderTypes {
        BoxCollider,
        TriangleCollider
    };

    class Collider {
        ColliderTypes type;
        JPH::Vec3 scale;
        JPH::Vec3 center;
        JPH::Ref<JPH::Shape> shape;
    public:
        // Constructor.
        Collider(ColliderTypes type, const JPH::Vec3& scale, const JPH::Vec3& center = {0, 0, 0})
            : type(type), scale(scale), center(center) {}

        // Copy constructor.
        Collider(const Collider& other)
            : type(other.type), scale(other.scale), center(other.center), shape(other.shape)
        {
            if (shape) {
                std::cerr << "[DEBUG] Collider copied successfully. Shape ptr: " << shape.GetPtr() << std::endl;
            } else {
                std::cerr << "[ERROR] Collider copied but shape is nullptr!" << std::endl;
            }
        }

        // Assignment operator.
        Collider& operator=(const Collider& other) {
            if (this == &other)
                return *this; // Avoid self-assignment
            type = other.type;
            scale = other.scale;
            center = other.center;
            shape = other.shape;
            if (shape) {
                std::cerr << "[DEBUG] Collider assigned successfully. Shape ptr: " << shape.GetPtr() << std::endl;
            } else {
                std::cerr << "[ERROR] Collider assigned but shape is nullptr!" << std::endl;
            }
            return *this;
        }

        // Sets the shape.
        void setShape(const JPH::Ref<JPH::Shape>& newShape) {
            if (!newShape) {
                std::cerr << "[ERROR] setShape received a nullptr!" << std::endl;
                return;
            }
            shape = newShape;
            std::cerr << "[DEBUG] setShape successful. Stored Shape ptr: " << shape.GetPtr() << std::endl;
        }

        // Returns the shape.
        const JPH::Ref<JPH::Shape>& getShape() const {
            return shape;
        }
    };

} // namespace BlockyBuild

// --- Main demonstrating Collider copy/assignment ---
int main() {
    using namespace BlockyBuild;

    // Create a dummy shape.
    JPH::Shape* dummyShape = new JPH::Shape();
    JPH::Ref<JPH::Shape> shapeRef(dummyShape);

    // Create a Collider and set its shape.
    Collider collider(BoxCollider, JPH::Vec3(1, 1, 1));
    collider.setShape(shapeRef);

    // Copy the collider.
    Collider colliderCopy = collider;
    if (colliderCopy.getShape())
        std::cerr << "[DEBUG] colliderCopy shape ptr: " << colliderCopy.getShape().GetPtr() << std::endl;
    else
        std::cerr << "[ERROR] colliderCopy shape is nullptr!" << std::endl;

    // Assign the collider to another instance.
    Collider colliderAssigned(BoxCollider, JPH::Vec3(2, 2, 2));
    colliderAssigned = collider;
    if (colliderAssigned.getShape())
        std::cerr << "[DEBUG] colliderAssigned shape ptr: " << colliderAssigned.getShape().GetPtr() << std::endl;
    else
        std::cerr << "[ERROR] colliderAssigned shape is nullptr!" << std::endl;

    // Clean up.
    delete dummyShape;

    return 0;
}

I have tried to set a JPH::Ref<JPH::Shape> in a class by setting it by a class member function but the data got lost when I tried to make a body with the shape in the reference...

[jrouwe]

I have noticed that mShapePtr in JPH::BoxShapeSettings settings in PhysicsEngine::addBody is set but not mShape but I don't know why...

mShapePtr contains the Shape object as it will be used by the engine
mShape contains a ShapeSettings object that is used to create the Shape

you can provide either to the BodyCreationSettings constructor and it will make sure that by the time the body is added an actual Shape is created.

This should not compile because Shape is a pure virtual class:

JPH::Shape* dummyShape = new JPH::Shape();

If you pass a pointer to a Ref then lifetime is managed by it and you should not call delete:

delete dummyShape;

[Sekaus]

How can I set mShape in settings so I can use it in bodyInterface.CreateAndAddBody(settings, JPH::EActivation::Activate)?

[jrouwe]

You can just pass the Shape or ShapeSettings object to the constructor of BodyCreationSettings or call BodyCreationSettings::SetShape / BodyCreationSettings::SetShapeSettings. You should not have to worry if the mShape pointer is set or not, that will only get set when you're passing in a ShapeSettings object.