OpenTTD | OpenTTD is an open source simulation game based upon Transport Tycoon Deluxe | Game Engine library

For the last few weeks, I've been trying to develop an isometric, tile-based tycoon-style crafting game in my spare time (and really only to see if I am capable) and I have run up against a design challenge that I am struggling with. I have successfully implemented ground tiles and drawing them, et cetera, using a Tile class (held inside a Map class), but I would like to now be able to add objects on top of tiles.

I have been able to create and render objects (like a table) using a fairly clunky debug class, contained within the Map class as a std::map and giving Objects X/Y coordinates so the Map can render them in the right places. All of this, while maybe not being the best approach, works, until I try to subclass Objects to give them different functionality.

I had (wrongly) assumed that I would be able to have some sort of heterogenous container for all objects on the map, which I could loop through and run object-type-specific logic during the game loop. I haven't fully scoped out the game yet, so at the moment I was just giving different objects different member variables - such as a container object that has a capacity, a heater object that has an energy rating, and so on. My first test was going to be to be able to place items on the map and then be able to query the sum of, say, all of the capacities of the container objects - just to make sure it works before moving on to the next step.

I've been trying to use open source projects like OpenTTD and some of the Habbo Hotel emulators to figure all of this out, but to no avail. I'd love to hear what others would think the best way to approach this problem would be.

I've experimented with dynamic_casting and using pointers in my map, but from other answers I've seen, this doesn't seem to be a particularly good way to do it. Should I be creating a pool of objects of the same type and then iterating over each pool during the game loop to keep things more simple?