Experiences with new graphics renderer and AI-related questions

Hello there, everybody!

I haven't posted here for a veeery long time, but I'm still around and still read the forum, if not even showing up myself too actively.

Recently openBVE 1.7.1.5 was released and I installed it. I've been using the new, OpenGL 3.0 based graphics rendering engine since 1.7.1.3 version, and now I want to share a few of my experiences.

First of all, I'm happy to see that 1.7.1.5 fixed a very ugly bug with making a passenger information database system screen made using OS_Ats1/BVEC_Ats plugin: when the screen was about to switch the display on the screen, after one frame of the intended display it always jumped back to the first texture display until 1.7.1.4. I want to say a big Thank You for the fix!

Second, now comes the not so good part. OpenBVE 1.7.1.5 introduced a new lighting/illumination system that I've just tested out. Well... I've found a very noticeable issue with that: the lighting might differ with every single time reloading the chosen route. I've chosen the MÁV railway line nr. 30 (Budapest-Déli - Székesfehérvár - Siófok) route built by Tibitrain and the Venice Simplon Orient Express train by Alejandro Melo for the testing. I now attach you three screenshots to illustrate what I was talking about.

Test #1: openBVE 1.7.1.5, OpenGL 3.0, while recording the gameplay at 60 FPS/12.8 Mbit/s with OBS:


Test #2: openBVE 1.4.3, OpenGL 1.2, no gameplay recording:


And finally, test #3: openBVE 1.7.1.5, OpenGL 3.0, all settings the same as in #1 but not recording the gameplay.


Now compare the results to each other... Something really seems wrong with the new rendering system.

Third. I've noticed that the AI driving of ALL openBVE 1.4.3+ versions are way worse than in 1.4.3. I've found the difference especially arguing on BKV Budapest Metro line M4 route, which was optimized for AI driving, simulating the truly existing ATO (Siemens CBTC) system quite accurately. Well, the newer versions don't let the automatic train operation work as it was intended for openBVE 1.4.3... The AI drives very much differently and is WAY less realistic than as it was in openBVE 1.4.3, killing the main point of the M4 line.

If possible, could I request to add an old (1.4.3) AI mode able to be turned on/off the same way as the new renderer can be turned on/off too for the newer openBVE versions?

I would be very happy if I could finally get over openBVE 1.4.3, but the crap AI driving of the newer versions makes me keep need to using it.

Please, if possible, give us this option.

Thank you for reading and have a good evening.

Cheers, Marci

Directional light isn't yet quite right with the new renderer.

(Lighting is hard, and imitating an existing GL1.2 renderer in GL3.0 is harder yet )

https://github.com/leezer3/OpenBVE/pull/482
This is likely to make things a lot better, but we're stull working on it.

AI:
As far as I'm aware, there have been no fundamental changes to the AI, certainly nothing in terms of the driving profiles in general. Some fixes to things like bouncing on the brakes, but that's about it.

https://bve.hu/muzeum/#M4BudapestFiktiv
Is that the route you're trying?
Default train?

Will take a look at exactly what's going on.

Nope, I have my own version of M4 line, which is available from my own homepage, and it has its own dedicated default train (Alstom Metropolis AM4-M4).

The BVE Club Museum version is very outdated and unrealistic, so therefore I started making my own M4 line route in early 2014, which already has way more realistic track path than the BVE Museum version. As the real life M4 route is equipped with Siemens CBTC ATO system, I tried simulating it optimizing the speed limits for the AI driving of openBVE 1.4.3 which back then worked very well. Then came the newer versions of openBVE and it all went wrong.

Where the AI should have first accelerated to 34-36 KPH and keep speed constantly for one second just after the stations' exit points, and after a second, accelerate again, this method worked greatly in openBVE 1.4.3. But in the newer versions it only accelerates to like ~30-33 KPH then fully stops accelerating for seconds, not even just getting back to constant speed level of handle position, it fully runs it out (X/zero position), and even after that it won't reach the same speed as it did in 1.4.3. And the suddenly huge and inaccurate braking is also a very bad point of the newer versions - 1.4.3 had a more accurate and more realistic braking system.

I've recorded a where I compared the true line to the simulation in openBVE 1.4.3 - take a look below at how the train drives itself in real life with the CTBC and how it worked in openBVE 1.4.3. Then download the line from my homepage and try it out in openBVE 1.7.1.5 version... You'll surely see a huge difference in favour of 1.4.3. So it is a FACT that AI driving is highly modified since 1.4.3 - and its development got in the wrong direction: newer AI drives much worse than the older one.

I'm really not seeing such a drastic difference between the two, and definitely not anything AI related.
I have also run through all the changes to the AI code, and there's nothing affecting braking or acceleration behaviour at all.

I get a minor difference between runs on either version, but that's down to the slight randomisation of passenger weights and the random factor of handle application times / specific limit adherance in the AI nothing more.
Remember that the AI is designed to mimic a human driver physically using the controls / limits, not a computer driver, and has an inherant 10% variance factor (anywhere from 90% of limit, max accel etc. to 100%):
https://github.com/leezer3/OpenBVE/blob/master/source/OpenBVE/Game/AI/AI.SimpleHuman.cs#L31

Well... If the AI is designed to mimic a human driver, then seeing what AI in newer openBVE versions do is even more tragic. xD

At us in Hungary a real human motortrain driver usually starts braking using the EP brake 3-4-5 times as far as of the allowed speed limit converted to metres - for example, at 120 KPH from ~400-600 metres, at 60 KPH from ~200-300 metres, etc. - from the stopping/halt point, and doesn't suddenly apply 3-4 brake notch levers, only one or maybe two, then after ~60-100 metres increases the braking force and keeps it until finishing the EP brake at ~4-6 KPH, then usually stops with 1-1.5 bar air braking power. This is quite a normal human-like braking with trains.

Now, the AI in openBVE 1.7.1.5 is not even close to this behavior. If the real human drivers did what openBVE AI does, then everyone would fall of their seats instantly...  So realism isn't really on top. Even an ATO like this Siemens CTBC (or the AVR PA mode on Budapest M3 metro line) brakes more comfortably and more reliable than as openBVE AI does.

Maybe it's just my opinion, but I think it could be done way more human-like, if that is the intention. Even Hmmsim 2's AI drives more accurately, if not yet more comfortably...

I've observed some AI oddities compared to 1.4.3 some time ago too. Trains had increased tendency to miss stations for a while, but since the AI now seems to work as it used to, I assumed it was fixed

It still tends to do very unnatural things though (and has always did), something neither a driver nor any sensibly made ATO would do:
- Stopping at stations using a lot of relatively short brake applications (setting brakes to some notch and then to 0, then to the same notch again)
- On many trains with simple air brake, there's super fast alternation between LAP and SRV that makes a pretty messy sound if brake handle has them.
- When a train is crawling to the stop position a bit slower than usual, AI will start applying power at around 0.5m before the precise position, almost always going beyond P1, this, combined with handle delays, leading to overruns of up to few metres. Sometimes doors will open while still rolling at a very small (below 1 km/h) speed.
- AI absolutely disregards wheelslip and keeps trying to accelerate at a max notch even if the actual acceleration falls to almost 0.

Delsin, this is exactly what I was talking about. So yeah, AI in 1.4.3 did these much less noticeably and with less failings.

Another big problem is that the AI doesn't care correctly about speed limitations. Where the train could go with 120 KPH and a real train driver normally accelerates to 115-119 KPH and tries to keeps that speed constant until the next station's/speed limit's braking distance, the AI only accelerates to 110-113 KPH and even if you manually increase speed to 115-120 KPH, it instantly cuts off power to zero, which is already not realistic, but when a negative pitch value comes and the train starts accelerating from just rolling down the slope even without giving power, AI only starts braking when it already has more than 5 KPH of overspeeding.

In Hungary where the speed limit is 120 KPH, noticing 126 KPH measured speed could be already a certain cause for speeding fine/other, even worse penalty/punishment to the train driver. This is already quite an important reason why I don't think AI should let more than 5 KPH rate of overspeed without braking back to be within the speed limit - we shouldn't show gamers that overspeeding is so highly tolerated while IRL it isn't.