When did I say this? I said that OS-specific optimizations are rare. I didn't say that porting to another OS or rendering library is easy.
Yet, Half Life 2 runs faster on Linux because...Muh linux. Code optimization doesn't make a difference, apparently.
Perhaps you misunderstand what I mean. I'm not saying porting to another OS is easy or trivial. It can be very difficult, depending on the versatility of the game engine and whether or not you support DirectX or OpenGL. I've not saying Linux ro Windows is better or anything, I'm just saying that the general optimizations in the engine contribute more to the end performance boosts than rendering library-specific optimizations (for example, Source's use of PVS to cut down on rendering times).
Ahh, we have a miscommunication on both ends.
I'm not talking about general optimizations, either. My point about bringing up Havok was that, if the parts of your engine that tend to be taxing or complicated are written in a shoddy way, it's going to show, especially those that require specific libraries.
Just to prove I'm not talking out of my ass, here's a fairly recent thing I made showing some AI steering behaviours, formation assignment, and spatial partitioning optimization: https://www.youtube.com/watch?v=k4FJs3_JgnQ
That's actually kind of cool. What, exactly, are you going to use it for? It's not the most complicated thing I've ever seen, but it looks like it has potential.
And here's a physics demo I've written showing the difference between an impulse-based and penalty-force collision resolution: https://www.youtube.com/watch?v=UrO4-OWEDNs
Again, another thing that, while it doesn't seem fully-fledged out, looks like it has potential. Again, what are you using it for.
Is my work on the same scale as creating fully fledged game engine? Is it perfect or even usable in a game? Of course not, I'm but a single man making prototypes. However, it shows (if nothing else) that I have at least a rudimentary understanding of the topics here, and programming knowledge.
You use the term "simple engine," which is a very loose term. I took it to mean an extremely basic and shitty engine, I apologize, What I interpreted it as was "Uh made a gaem and Ahve read buks!"
Please could you show a similar portfolia of work you have done, if for nothing but to prove me the fool?
I'm only in Game Development as a hobby. I used to use Unreal, but hated every single moment of it and I never seemed to get anything done. Most of my projects ended up being scrapped in the end.
However, I've moved to source recently and I'm already doing better than I was when I was using unreal. Nothing spit-shined to show now for what I'm currently working on.
I will say, however, that I have no use to make my own engine. Source does pretty much everything that I need it to do, and the things that it doesn't do or does poorly aren't going to be too hard to tackle. And, as this is my hobby, I don't have a portfolio ready for you (Why would I? I don't intend to work in the industry.)
I wouldn't know what to show you, anyway. Because the engine handles almost everything I need, most of what I could show you is art, anyway.
However, I have years of programming experience, just not as much in the game industry.
However, the argument we are having right now is about the in-depth internal workings of game engines, and it's not really possible to explain that in a couple of Reddit comments.**
It's possible to write a very-lengthy book on game engines and still only scratch the surface on huge parts. It'd take a series to cover most of the content.
So, no, we're not really going to go in-depth here.