Vertical sync affecting enemy behaviour?

[Frans Cantor]

Enemy AI seem framerate dependent, big FPS makes them less aggressive. Video included

Hello all!

I pre-ordered Elite: Dangerous few days ago so now I have been playing the Single Player Combat Training quite a lot, and have noticed a strange behaviour. I can usually make it to Anaconda with around 100% hull and with only beam laser because I want to save the cannon ammo. Today the game seemed a lot more harder, and I died in the first wave with 3 ships, Sidewinder and 2 Federal Fighters I believe? Usually the Federal Fighters have been next to harmless but now they were tailing and shooting at me all the time while I was trying to nail the Sidewinder. The Federal Fighters in earlier waves were also clearly harder than before. Usually they could be easily tailed and killed, but now it was very hard to tail them and they actually shot at me quite often, unlike previously. All ships felt a bit harder but especially those Federal Fighters which had earlier been useless pushovers. I tried to check if there was an update or something to make the AI better, because they seemed a lot more aggressive. I was convinced that there must be a reason to this, and then I remembered that I had enabled vertical sync. Usually I don't use vertical sync because for example in FPS-games it can make the mouse feel laggy, so it had been off earlier.

Then I tried again few times taking turns with vertical sync on and vertical sync off with the same results: it was much easier with vertical sync off. Performance is good with both v-sync on and off, so it shouldn't matter performance wise. Of course, with vertical sync off there is small tearing and fps is around 80-120, with vertical sync on the image is smooth with no tearing and fps is capped at 60, but the enemies feel smarter and more aggressive!


To summarise my observations.
With vertical sync off:
- I can play almost perfect games to Anaconda.
- Federal Fighters rarely shoot me.
- Federal Fighters commonly fly around aimlessly when I'm dogfighting others.
- In waves with 3 ships, If I'm dogfighting a ship I can see from sensor that at most 1 other ship is shooting at me at a time.

With vertical sync on:
- Hard to make it to Anaconda.
- Enemies seem harder. They dodge and shoot more and are harder to tail. Especially Federal Fighters are much more aggressive.
- Federal Fighters DON'T fly around aimlessly. They are much harder to tail, and if I dogfight with other ships the Federal Fighters are constantly on my back shooting me.
- In waves with 3 ships, I can see from sensor that all 3 ships are shooting at me at the same time.

I feel that the game behaves in the correct way when v-sync is on. With it off the enemies feel a bit useless, thus it would be v-sync off which presents weird behaviour... It is easiest to see in the waves with many enemies, and the effect is instant. If those little Federal Fighters are shooting at you, go to settings and turn v-sync off and they start to fly away and around aimlessly without trying to shoot you much. I can record a video of this if no one else can recreate this effect. Please test this few times with alternating v-sync on and off and share your results!!

EDIT: FromtonRouge made a video about this [video=youtube_share;qhCSLYGzDbM]http://youtu.be/qhCSLYGzDbM[/video]

 

[gamecat]

That's bizarre!

 

[bassman]

Hello all!

To summarise my observations.
With vertical sync off:
- I can play almost perfect games to Anaconda.
- Federal Fighters rarely shoot me.
- Federal Fighters commonly fly around aimlessly when I'm dogfighting others.
- In waves with 3 ships, If I'm dogfighting a ship I can see from sensor that at most 1 other ship is shooting at me at a time.

With vertical sync on:
- Hard to make it to Anaconda.
- Enemies seem harder. They dodge and shoot more and are harder to tail. Especially Federal Fighters are much more aggressive.
- Federal Fighters DON'T fly around aimlessly. They are much harder to tail, and if I dogfight with other ships the Federal Fighters are constantly on my back shooting me.
- In waves with 3 ships, I can see from sensor that all 3 ships are shooting at me at the same time.

I feel that the game behaves in the correct way when v-sync is on. With it off the enemies feel a bit useless, thus it would be v-sync off which presents weird behaviour... It is easiest to see in the waves with many enemies, and the effect is instant. If those little Federal Fighters are shooting at you, go to settings and turn v-sync off and they start to fly away and around aimlessly without trying to shoot you much. I can record a video of this if no one else can recreate this effect. Please test this few times with alternating v-sync on and off and share your results!!

Sync off puts more frame geometry load on the CPU (since its having to pre render more frames per second) so this may be causing starvation of CPU time to the AI calculations. Never seen this happen in a game before though since you would generally give enemy AI the highest CPU priority so as to get consistent behaviour at different graphics loads.

 

[SuperGhostMaster]

Sync off puts more frame geometry load on the CPU (since its having to pre render more frames per second) so this may be causing starvation of CPU time to the AI calculations. Never seen this happen in a game before though since you would generally give enemy AI the highest CPU priority so as to get consistent behaviour at different graphics loads.

This is completely ridiculous. The processing is done on GPU and has nothing to do with the AI logic of the game.


No, it is not possible that V-Sync affects the AI difficulty level.

 

[Frans Cantor]

I may very well be wrong. Maybe it was just bad luck. I hesitated to post this since it is a bit far fetched...

Well, a priori, fps can affect gameplay. For example: http://steamcommunity.com/app/294860/discussions/0/624075036381183226/?insideModal=1

 

[zynaps]

This is completely ridiculous. The processing is done on GPU and has nothing to do with the AI logic of the game.
No, it is not possible that V-Sync affects the AI difficulty level. This is a troll.

True, the amount of geometry probably doesn't affect the AI, but it's entirely possible that Frontier designed the engine in such a way that the think() function runs once per frame as opposed to a fixed rate per second. The Cobra game engine is a console oriented engine ported to PC and on consoles most games runs at a fixed FPS. If this is the case then the frame rate would affect the AI since NPC ships are client-side, but I can't believe they would actually make such a mistake.

 

[fourty6to3]

Come to think of it, a few games I've played, like Skyrim, the AI would act kind of wonky when forcing v-sync off. I just tested this with incursion, and the AI is definitely harder with v-sync on. The cobra got me down to 68 percent with it on, and didn't get my shields down with it off (seemed like he was aiming at someone else). Also the two federation fighters would both attack aggressively with v-sync on, and with it off they would fight one at a time. This is interesting.

 

[fourty6to3]

One of my friends is a pre-order backer, so he just has access to the combat missions. Of which, I told him to practice incursion and over the course of a few weeks he's finally made it up to wave 7. I asked if he had v-sync on and he said yes. I told him to turn it off and try incursion again, but didn't tell him why. Well, he made it to the last wave and said it seemed easier. So it looks like the AI is working as intended with v-sync on, and I've been playing it this whole time with it off (I always turn off v-sync in my games). Turns out I also have trouble making it past wave 7 now

 

[jpaulwilson1982]

I can't get past the last training mission, either. I'll try it and post my results.

 

[FoxTwo]

Hmm I have v-sync off in ED but I have it set to "Adaptive" in nVidia control panel.

I'll see what results I get.

 

[Asp Explorer]

This is extremely interesting - I'll have to give it a go with vsync on/off soon and see if there is any difference.

It may take a while though - in my haste to reformat this rig and go through the whole reinstall and start as a noob thing again - I forgot I couldn't read RAID 5 volume entities as separate disks plugged into another machine.

I'm paying for that now, and will be for a very long time <cries>

 

[jpaulwilson1982]

I just tried the last training mission with v-sync off, and there was no difference. Still just as challenging, still getting killed at the same point by the same pilot. Which, if it were easier I wouldn't consider it a real victory if I won. Anyways, there was no difference in AI difficulty on my PC. Perhaps its possible I'm just that​ terrible? lol

 

[Eldan Cross]

definitely interesting to test. In my experience, all waves get easier if you have good aim. If you don't shoot them enough, they pound you. if you shoot them, they "get scared"
seriously, there's a big difference in how a wave plays out if you keep pounding something. or if you keep missing.
you see the enemy makes some distance then turns and starts shooting at you. if you keep shooting at him even if he is far away, AI will get the "oh i'm being shot at, lets scram" and not hit you too much, most of the time.
I can complete all 10 waves no problem, vsync on or off.

I did have a few games where it seemed harder to finish, but after revaluating, i found that if i pound them HARD, they go down easy. and fast. even wave 9 is a joke if you forget about shields and engine and go full on weapons and boom. they fall pretty fast.
Work on your aim guys!
The only exception to this is the wave 10 anaconda, which starts shooting me(and hit me) at about 3+km. But if you start translational thrusters and go around it then it misses. sweet spot seems to be around 2.10km going full up or down thrust with zero engines and throttle on the negative, just enough to keep a steady distance. when it gets a lock on you just change translation to up or down and keep at it.

*edit: i just had a quick run with vsync on. can't say i noticed some difference. i did lose 50% armor in wave 9. but sometimes that's expected i guess. ships did seem to hit me more often but i might be biased. didn't do my best either xD so v-sync off-on seems same to me at least.
on another note: 8core, playing on high, limited fps to 60hz. can't say i'm experiencing any screen tearing with vsync off, playing always with vsync off to limit input lag. same reason as setting polling rate to 1000hz ^^ (mouse+keyboard)

 

[Lange_666]

Sync off puts more frame geometry load on the CPU (since its having to pre render more frames per second)

You need to review your knowledge of VSync...

 

[Jim LeCreepé]

In some games vsynch off messes up the physics calculation (Skyrim for example). Some games are frame locked (which NFS game was it again?) and don't work with more then the fixed set of fps. I play without v-synch, did not test the difference though. Would not be too far fetched that the frame rate somehow messes up calculations in-game.

 

[Quietman]

Sync off puts more frame geometry load on the CPU (since its having to pre render more frames per second) so this may be causing starvation of CPU time to the AI calculations. Never seen this happen in a game before though since you would generally give enemy AI the highest CPU priority so as to get consistent behavior at different graphics loads.

This is completely ridiculous. The processing is done on GPU and has nothing to do with the AI logic of the game.
No, it is not possible that V-Sync affects the AI difficulty level. This is a troll.

You need to review your knowledge of VSync...

Bassman's terminology may not be 100% correct and there may be some confusion in the wording of his message, but there is nothing wrong with the foundation of his statement.

A locked VSync renderer has less CPU work to do than a non locked VSync renderer, this could potentially lead to less cycles available for AI, (depending on the engine), even if it is multi-threaded and/or multi-core. The logic is simple, if you are traversing a scene graph, culling, clipping and presenting draw calls, (this is all basic CPU rendering work), at 60FPS; it's obviously less CPU work for a given time interval, compared to doing the same thing at 100FPS.

With all that said, I would be terribly surprised if ED's AI thread was coupled to it's rendering thread; typically AI and physics are run on separate threads at semi-deterministic intervals, (e.g. 100Hz), whilst the rendering thread runs at a completely different frequency, (depending on factors such as VSync, GPU speed, game's chosen graphic settings, etc).

This is an interesting thread and nothing is black and white in complex multi-threaded and multi-core games, as I said I would be surprised if the AI and physics of ED was coupled in anyway to it's rendering, but I would also not rule out complex interactions due to issues such as:

- Not 100% decoupling of AI and rendering.

- A bug in the AI that makes it seem it is VSync dependent.

- The almost infinite variability in user's hardware and software configurations.

It's extremely difficult to test situations like this, unless the behaviour discrepancies become obvious, (such as the AI not firing, or coming to a dead stop, etc), and is subject to personal interpretation; with that said I would still ticket it so that someone at FD at least knows there is a potential issue.

 

[Sitasan]

i never managed to finish all the waves, but was v sync on all the time.

after reading this message, i give it a go with v sync off...and finished the last waves finger in the nose (or so)...but i cant be sure that it s not related to my experience in the game...i play a lot more than when i first try it...but i think the AI seems a litle bit more...stupid...i dont know...it s interesting...hope some more smarter pple than me will find out

 

[Dissentient]

Vertical sync increases input lag, you may perform significantly worse because of it.

 

[Frans Cantor]

Vertical sync increases input lag, you may perform significantly worse because of it.

I tried to say in my opening post that the performance is not issue. I feel like I can hit as good, but it is the other ships who shoot me more intensively, not the one I'm chasing.

Good that you guys are getting the same results. Sounds exactly what I was talking about. I thought i was just getting paranoid.

even wave 9 is a joke if you forget about shields and engine and go full on weapons and boom. they fall pretty fast.

*edit: i just had a quick run with vsync on. can't say i noticed some difference. i did lose 50% armor in wave 9. but sometimes that's expected i guess. ships did seem to hit me more often but i might be biased. didn't do my best either xD so v-sync off-on seems same to me at least.
on another note: 8core, playing on high, limited fps to 60hz. can't say i'm experiencing any screen tearing with vsync off, playing always with vsync off to limit input lag. same reason as setting polling rate to 1000hz ^^ (mouse+keyboard)

Yes, with v-sync off I can almost forget about shields and kill them one by one. But with v-sync on not a chance.

 

[FromtonRouge]

Ok I just tested with v-sync off and wave 7 and 9 were too easy. In wave 7 I was able to fly behind "The Colonel" during 1 minute without being attacked by the 2 Federal Fighters (maybe they shoot me 2 or 3 times but just some bullets). "Big Mama" was also easier to destroy (I was able to fight at a distance of 800m-1500m). So there is something wrong