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Physics optimisations bugs when idle
1
(27 posts, started )
Handbrake changes gear with engine off
Go from the pits witth any road car, stop somewhere, change to neutral gear and press the ignition button to turn off the engine. Then change gear from neutral to e.g. 1st gear (without the clutch), it will stay on neutral. But: Change gear without the clutch to 1st and then press handbrake - it will change the gear to first. Works with all the gears (1st - 6th).

EDIT: Change gears without the clutch!
If you are completely stopped and the engine is off, you should be able to shift without the clutch...
Quote from wheel4hummer :If you are completely stopped and the engine is off, you should be able to shift without the clutch...

yes, so it's a bug when you are stopped and engine is off and when you can't shift without a clutch.
Oh. It worked for me.
I have G25. So i stop and set to neutral and turn the engine off. Then when I change to 1st gear on my H-shifter without clutch pedal, in stays in neutral. But then when I press the handbrake button, it will change to 1st.
I cannot test it right now, but are you sure that your handbrake button hasn't clutch mapped on it too? (for drifting purpose maybe)
Anyway, on a real car, it is advised to press the clutch when shifting even with the engine turned off.
Quote from Flame CZE :I have G25. So i stop and set to neutral and turn the engine off. Then when I change to 1st gear on my H-shifter without clutch pedal, in stays in neutral. But then when I press the handbrake button, it will change to 1st.

well, I can change through gears when the car is staying steadily without moving (maybe you were rolling very slowly?). Allthough sometimes it will go from 1-2-3, but won't engage 4th, if I press the gas pedal slightly, it engages. A bit weird
#8 - senn
Car tested with - XRT
Auto clutch OFF
Controller used DFP, gears mapped to stick in sequential mode, manual shift, clutch mapped to left paddle.

engine off, no revs, - Can shift to 1st without depressing clutch, but no higher. Once in 1st cannot shift up or down WITHOUT DEPRESSING CLUTCH. Depressing park brake and shifting has NO EFFECT WHATSOEVER

Engine on, idling - Can shift throught all gears with clutch depressed. Cannot shift through gears with handbrake on without depressing clutch.


Seems normal to me?
Did some testing too.

XRT at BL3 ( replay attached), G25, H-shifter, manual clutch

If you stall the car, by just letting the clutch too fast, it will shift easily through gears.
However, if you switch off the ignition, to get the 1st gear engaged, you need to either press the throttle a bit (that is whats weird) or use CL. It will go from 1st to second fine after, but to get further to 3rd, you'll have to repeat the above.
Attached files
ART_BL3_XRT.spr - 6.6 KB - 340 views
I think that what he means is that with the engine off, the handbrake button is for whatever reason, controlling the gears.
Quote from danthebangerboy :I think that what he means is that with the engine off, the handbrake button is for whatever reason, controlling the gears.

Same happend with pressing the throttle while the engine is off, both of those bugs seem to be have similiar causes anyway
Physics optimisations bugs when idle
Some time ago I found a strange bug in drivetrain system,
when the engine is off, wheel rotation speed increases from 0 to maximum possible speed.

To reproduce this bug, the following conditions must be met:
  1. Wheels that are powered by drivetrain can not touch the ground.
  2. Clutch pedal must be pressed.
  3. The engine must be down (just turn off the engine at full speed and wait for 0 RPM).
  4. Use the steering wheel to turn left/right or the accelerator pedal.
Watch the strange behavior of the speedometer, I think this is just bad optimization.
Attached files
Drivetrain bug.spr - 14.9 KB - 418 views
This is not a bug.

LFS turns out physics calculation when your engine is off. Untill you do some input, like stering, then the wheels will recover their real speed.
Quote from Whiskey :LFS turns out physics calculation when your engine is off. Untill you do some input, like stering, then the wheels will recover their real speed.

Everything is correct, bug is in optimization.

Physics calculations should be suspended only if both conditions are met (engine is off and wheels do not spin).
Looks like Scawen forgot about the second condition.
I agree, every car which is moving should have physics calculations done for it, regardless of whether the engine is on or off. This can also remove possible exploits, for example if a player turns off their engine to avoid the laws of physics!
The physics calculation only stops when the car is still. If you are upsides down, the car is still eventhough the wheels are spining. So I can't see any kind of exploit there
Physics stops calculating when ignition off
physics stops calculating when ignition off and no changes in input (steering, brake, thorttle, handbrake) , I will try to demonstrate this on few examples:

1. this is the same bug as Flame mentioned before for gears, link: http://www.lfsforum.net/showthread.php?p=892872#post892872

when ignition off lfs stops calculating physics, so basicly if you don't move any of axis you won't be able to change gear
like demonstrated in replay gear.mpr at the same moment when I send this text to chat, I change gear. But ingame gear changes when I move some of inputs (axis)

2. in replay bf1.mpr you can see my car fliped and when I'm not moving axis, after about second my wheels frezze and shows speed 0 kmph, but when I move axis it shows real speed.
Attached files
bf1.spr - 16.1 KB - 350 views
gear.spr - 4.9 KB - 309 views
Yes, you are right, but I am afraid that this is an optimisation rather than a bug, so I don't expect Scawen to change it.
I can't find any CPU usage difference in this two cases...

Maybe including shifter as input, and that it can stop calculating only if there is 0 kmph
Quote from DANIEL-CRO :I can't find any CPU usage difference in this two cases...

I guess it's more a network optimisation rather than a CPU one.

It could be better if wheel speed = zero, but again, this would only avoid fliped cars to enter in the "optimised mode", which wouldn't be desired either
Few more things (questions): sorry for offtopic, don't wanna open new thread

I think that SHIFT+J and SHIFT+S should work in lobby (or how is called this when you end race..) because SHIFT+J is generally "join race" and you are joining race at lobby, right?

When driving FXR I can shift without using clutch, even if in options there is autoclutch off. This is normal for sequentials?
For me its really confusing, because for example when I drive XFG, I press shift up like second before actually shift (pressing clutch).
Quote from DANIEL-CRO :I think that SHIFT+J and SHIFT+S should work in lobby (or how is called this when you end race..) because SHIFT+J is generally "join race" and you are joining race at lobby, right?

That is a good suggestion indeed.

Quote from DANIEL-CRO :When driving FXR I can shift without using clutch, even if in options there is autoclutch off. This is normal for sequentials?
For me its really confusing, because for example when I drive XFG, I press shift up like second before actually shift (pressing clutch).

Yes, you don't need to press the clutch in cars using sequential gearboxes. That's how it works.
Ok, one more thing..
been interested what will happen if load S2 replay (on BL1 or BL2) with locked (demo) LFS, result: playable replay but you can see only demo cars, and for others get message "Could not load nickname's car"... Should demo racers be able to watch S2 replays? maybe there should be some flag which content is used in replay..

sorry for spaming all over
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Physics optimisations bugs when idle
(27 posts, started )
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