Implement polymorphic hierarchies

I need an abstract base class Renderer with a virtual render(Entity const&) and a concrete OpenGLRenderer and VulkanRenderer that share a common ResourceManager pointer. Set up constructors, destructors (rule of five where needed), and demonstrate polymorphic use by storing unique_ptr<Renderer> in a vector and invoking render on two different concrete instances in main.

Before I hand this to the architecture review, make the polymorphic surface easy to approve: put the pure virtual methods up front, document ownership of ResourceManager, highlight where slicing or wrong destructor visibility could happen, and call out the simplest refactor to support shared render state across renderer implementations.

I changed the ResourceManager in Renderer from a raw pointer to shared_ptr to avoid lifetime bugs. After the change, some resources persist longer than expected and a test that relied on destructor side effects started failing. I need to explain what I changed, who uses Renderer, what I fear (leaks or altered destruction ordering), and ask: what is the likely cause and the best rollback or mitigation while keeping safe ownership?

Over several modules I keep choosing different ownership and destructor patterns for polymorphic hierarchies and that creates use-after-free or leaked resources in production. Which habit should I change to stop this cycle: recommend a consistent ownership convention for Renderer-like types, a minimal checklist for virtual destructors and smart-pointer choices, and one code review rule to catch violations early.