Rendering API Design Advice

[zacharyselk]

Hi there, I am building my own rendering framework (for learning and of course fun) with goals of someday having something similar to this project. I was wondering if anyone would be able to share any pointers or useful resources for making any of the relevant parts of the rendering system or things that would be good to keep in mind when designing general API for the various backend APIs (namely OpenGL, Vulkan, Direct3D, Metal, and WebGL).

Also, I was wondering if anyone has an opinion on what would be a good way of dispatching API calls to the various backends. I started with rolling my encapsulated polymorphism in the hopes of keeping by-value semantics in user code similar to this:

class IndexBuffer {
public:
  IndexBuffer(const Renderer& r, uint32_t* indices, uint32_t count);
  void bind() const { vptr->bind(); }
  ...
  friend class OpenGL::IndexBuffer;

private:
  // Virtual base class for polymorphism.
  class IndexBufferConcept {
  public:
    virtual void bind() const = 0;
    ...
  };

  // Custom virtual pointer to allow for value semantic polymorphism.
  std::shared_ptr<const IndexBufferConcept> vptr;
};

But that ended up getting too messy and I am not really sure if it is worth it, so I plan on starting from scratch using standard polymorphism with a pure virtual base classes unless I can find anything that might be better.

But in general, any advice would be hugely appreciated and I hope that this is an ok place to ask this question.