Ragdoll AI moved and twisted after reloading

[lost_soul]

I hadn't gone into that other room with the three beds during that game.

Edited October 20, 2011 by lost_soul

[Springheel]

No, that guy on the floor mattress is a ragdoll placed at map start.

[grayman]

I'm watching the AI in question at map restore, and in the first 519 frames, he slides off the bed and onto the floor. It's not a smooth change; he moves in short jerks every few frames until he ends up in his final position.

 

So now I need to find out what's pushing or pulling him off the bed.

 

l8r...

 

 

 

[grayman]

@lost_soul:

 

Where was the AI standing when you KO'ed him?

[grayman]

Status ...

 

I think this has something to do with intermittent thinking. We've seen a few physics problems occur due to IT, and this might just be another one.

 

When a savegame is restored, a KO'ed AI--even though he was at rest when the game was saved--is considered to be NOT at rest at restore time, and subject to the game's laws of gravity. If I KO a guard and drop him on a bed, then save and restore, that guard moves ever so slightly when he's restored. It's not enough that you'd notice while standing over him, but the code is moving him a tiny amount each frame until the amounts become small enough to consider him at rest, at which point physics turns off until you bump him or hit him with something later.

 

In the case of lost_soul's mangled guard, the player is far enough away at restore time that intermittent thinking takes over and time--and probably physics--distorts. The tiny nudge that gravity applies becomes amplified, and the body begins to move in a perceptible way. Any particular body might not move at all, but some might.

 

All this is just a SWAG, but it looks like this is where the code is taking me. (Of course, it might take a left turn later.) There are a billion things going on inside the physics code.

 

Atm, it doesn't look like the attached sword is causing the problem. The code checks the master first, which is the AI's body, then it checks the sword, then the head. If the sword or the head find that the master has moved, then they move accordingly. If the master doesn't move, they don't move. So the master is driving them, not the other way around.

[Tels]

Hm, is the "at rest" value never saved, or just not restored properly?

[Springheel]

Can interleaved thinking be turned off on ragdolls?

[grayman]

Hm, is the "at rest" value never saved, or just not restored properly?

 

It's restored to its saved value, but ignored. Probably to let entities settle down if they need to.

[grayman]

Can interleaved thinking be turned off on ragdolls?

 

It could be, but I don't know if that's necessary yet. If I'm right, then the more correct solution is to adjust the math to account for a longer-than-assumed time interval.

[grayman]

The correct solution--as Springheel suggested--is to turn off IT for KO'ed AI.

 

The code was already turning it off for dead AI, with the comment "Ragdolls think every frame to avoid physics weirdness."

 

Since KO'ed AI physically act the same as dead AI, I simply added a check for being knocked out.

 

In 5 tries, lost_soul's KO'ed AI stayed on the bed in the exact same position.

 

@lost_soul: Is this the position the AI ended up in when you dropped him on the bed?

 

[Springheel]

Wow, that could be an exciting fix...one of the very last gameplay-breaking bugs!

[grayman]

Wow, that could be an exciting fix...one of the very last gameplay-breaking bugs!

 

Uh-oh. Shouldn'ta said that.

 

(Applying anti-jinx finger movements to screen.)

 

[New Horizon]

lol Keeping my fingers crossed that this is the one that fixes it for good. Nicely done!

[lost_soul]

Yep, that screen shot looks about right. Nice work! I think he was standing near the front door of the building. He was the archer IIRC and I blackjacked him when he came out the front door.

Edited October 21, 2011 by lost_soul

[grayman]

Yep, that screen shot looks about right. Nice work! I think he was standing near the front door of the building. He was the archer IIRC and I blackjacked him when he came out the front door.

 

Ok, good.

 

He's not an archer, though. I wonder if you blackjacked him just outside the hall door that leads to the balcony over the large lodge-like room. It appears that the code keeps track of two AI origins, and one of them might be getting stuck at the spot where the AI gets knocked out. Because of "if it ain't broke don't fix it", I'm not going to figure out why this is.

[lost_soul]

Yeah I think you're right. Now that you mention it, I blackjacked the archer, chucked him over the (outside) railing and stashed the body beneath the stairs outside. That guy in the room is the one who patrols through the hallway.

 

EDIT: Just loaded up my game and checked. The archer is outside beneath the stairs.

Edited October 21, 2011 by lost_soul

[nbohr1more]

Great job Grayman (and Springheel) !

 

[grayman]

Fixed for 1.07 in source rev 5004.

[i30817]

The correct solution--as Springheel suggested--is to turn off IT for KO'ed AI.

 

The code was already turning it off for dead AI, with the comment "Ragdolls think every frame to avoid physics weirdness."

 

This was a optimization right?

[Tels]

That's nice work! At a later time we might want to revisit the "enable IT for dead/knocked out AI", tho, because now the game will get slower if the user knocks out/kills everyone on the level. (But hopefully dead/knockedout AI skip most checks in their thinking code, anyway?)

[i30817]

Then again, people should be testing their levels ghosting anyway. So it's not likely a map will require knockouts for performance.

[RPGista]

Great work guys. Untill the fix is out, just remember: cold assassination is the way to go!