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c++pointersraytracing

C++ finding type of subclass with a pointer to superclass

In my C++ code, I have a vector of pointers to a Light object. P_Light is a subclass of Light, and has a field position. For each pointer pointing to a Light that is actually a P_Light, I need to do something with the position field. I did some searching and it seems like I can implement a virtual method, but I don't need the method in Light since other types of Light don't have a position. I also thought about casting but I'm not sure how to make that work.

std::vector<Vector> light_dirs;
for(int i=0; i<lights.size; i++){
    Light *l = lights[i];   
    //cast here?
}

EDIT:: Saw in a different post that maybe using qobject_cast would be a good idea. Does this look better?

std::vector<Vector> light_dirs;
for(int i=0; i<lights.size; i++){
    Light *l = lights[i];   
    P_Light* pl = qobject_cast<P_Light*>(l);
    if(pl != nullptr) //dostuff;
}
Solution

  • This should work.

    P_Light* p_light = dynamic_cast<P_Light*>(l);

    Check RTTI and dynamic cast on https://en.wikipedia.org/wiki/Run-time_type_information