Just wanted to share some info that I got from
Neema, who is the guy in charge of hit reg related issues.
I sent him this
video of a stationery Banshee getting shot at in the CT to no effect (you can see the reticle never went red when I shot him at about 9 seconds into the video) and we talked about hit reg issues.
This was his initial response :
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I am not working on this currently. However, this is an interesting video. I've seen this kind of problem every now and then. I don't think this has anything to do with HSR or even lag. There appears to be some kind of bug in the game, where sometimes the CT of a mech stops receiving damage.
He further said that PGI couldn't reproduce these "no damage" instances in house so they made it lower priority for the moment (basically not working on it currently), but if people can identify some kind of common factor in these cases, they might be able to identify the cause and fix it.
In regards to poor hit reg in general :
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In our testing, the failures cases always involved small positional differences between mech placement on client and server. The problems often manifest with fast moving mechs, or quick shots where the player swings their arms quickly, etc in the presence of lag. Fixing this specific problem is not straight forward, due to some architecture details in the way the movement code works.
So yes, higher ping = more hit reg issues, and hit reg is worse when trying to shoot fast moving mechs in general or swinging your arms too quickly.
Back to the banshee taking no damage :
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With that said, we have never been able to reproduce situations that you have reported above with stationary, or slow moving mechs. Which is part of the reason why I speculate the bug is unrelated to HSR or even lag, but some kind of problem in our collision detection or damage calculation code. This is, of course, only speculation.
Recap on HSR (Host State Rewinding, which is the anti-lag feature in MWO) :
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HSR (Host State Rewinding) specifically "rolls back" the state of the server to the time at which a player perceived their weapon shooting (a player's perception of the server's state is delayed due to lag). Upon rollback, the server then performs the shot as normal, any hits that occur are then considered valid. The effect is that the targets should now be under your crosshair on the server (assuming your aim was accurate) when the shot is performed. This is a bit more complicated for projectiles, but its the gist of how it works.
In regards to shots doing damage to the rear even though the mech is shot from the front :
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Regarding the shots dealing damage to the back of Mechs even though they are hit from the front, I am not certain about what causes this. I was just speculating that it could be a bug in the damage calculation code, but it certainly could be a bug in the HSR algorithm as well, or even a bug that only manifests when the two systems interact in a specific way.
Conclusion :
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Yeah, it should be fine to tell people what I said. I would love to fix these bugs and improve the game for you guys
If I can get a good lead, I might be able to up the priority and spend some time on it.
So basically, if you can get more videos of weird hit reg issues, send them to him. Also helps if you can identify some kind of common cause.
Feel free to repost this on reddit or wherever.