Tile transitions - external vs internal

Question

I've been looking at a couple of games and noticed that the transitions between tiles are handled somewhat different.

I was wondering which methods are to be used in different situations and why. I'm currently using internal edges in a top-down game, and it's working out so far. But I don't want to run into problems later on, and have to redo the whole tileset.

I noticed that platforming games mostly use the internal edges, and top-down games mostly use external and hybrid transitions. I can see how these tiles are used to create "depth" in top-down games, where the player apears to be standing in front of a wall for example. But it seems unlikely that such a small feature decides the entire method for tile transitions. You could always alter the bounding box to create the same effect.

Answer 1

On the one hand, your distinction between internal and external transitions looks like kind of a false dichotomy to me. In both cases what you have is tiles depicting a transition from two types of terrain, say sand and water. The only difference is how much sand is depicted vs. how much water. That isn't any sort of technical distinction, just a difference in how the artists choose to draw the tiles.

That said, the main technical difference I would expect from different tiling choices would be in collision detection. For example, if the character moves through water but not sand, then is this transition tile considered water or sand? However this is similar to the case you pointed out in your question, a technical situation that could easily be addressed by altering the bounding box of the tiles.