Gamedev Lounge 0010

[Hoeloe]

Not trying to come off as provoking; I'm simply stating the facts. Yeah, you can get some "oomf" to the power of your own custom engine. But it's extremely tedious to pull library from library and make everything work together. Why not use something hundreds if not thousands of other developers can confirm already works and save yourself hours of headache?

Well, you might think so, but not necessarily. It will be extra work, but the result will be better if you can pull it off. The reason being that the specification of engines changes depending on the project, and using a pre-built one means you have to work around it, rather than the other way around. You can get pre-built engines in a code-based scenario as well, but you have the ability to tweak and tailor them to your project.
There will always be limits to what a pre-built engine can do, and that's fine, but by limiting yourself further by using a GUI-based editor, you make it harder for yourself in the long run.

Not just that, but things can be more readily managed and controlled in a code-based system. I've already talked about memory management with respect to load times, but let's say, for example, you have a shmup game, which requires that a) a lot of objects be drawn on screen at once (some hundreds, or even thousands), and b) it maintains a steady 60 FPS during gameplay (since otherwise lag would make the game unplayable, because the slightest loss of control could cause death). Chances are, a ready-made game engine won't be able to pull this off out of the box. What you really need to do is optimise it in the classes. Collision detection for example. You don't even know how your pre-made engine is going about it. It might (and likely will) collide a circle against a circle with a circular detection. But, however, you might want to use rectangular collision detection, because it is much cheaper, and would give a result that is more or less what you want. You also want to make sure your data structures are set up in a way that doesn't take much time to initialise, otherwise firing a lot of bullets at once in this example will cause lag. Again, you don't have access to this in a pre-built system. etc.
If you have an engine that is tweaked automatically, it is almost certain that issues like this will build up, simply because there's no way to manage them. Without telling the program exactly what you want (i.e. through code), it has to guess, and this can produce issues, especially in a system where performance is important.