Openrct2: River rapids get stuck on lift hills

[deurklink]

OS: [Windows 10]
Version: [0.1.2]
Commit/Build: [57be3b4]

River rapids sometimes get stuck on lift hills. Few weeks ago i also saw a splash boats ride which sometimes got stuck on a lift hill, probably related. I have attached a save where two river rapids rides are stuck. One is completely stuck, the other one (river rapids 1) has one car stuck on a lift hill which stays there until pushed off by the next, which then gets stuck.

• [ ] Reproducible in RCT2 (vanilla)?
• [x] Multiplayer?

Steps to reproduce:

1. Build river rapids or splash boats
2. Watch them sometimes get stuck on a lift hill

Screenshots / Video:

Save game:
Multiplayer park - Squares 8.zip

[deurklink]

Here's another save, with boats almost crawling forwards and a huge pile of boats behind them. I got this situation after fastforwarding for many years.
Multiplayer park - Squares 8-1.zip

If this save is fastforwarded for a bit (2 cycles of the cars moving up the lift hill) it usually ends up getting stuck.

[deurklink]

Now that I think of it, sometimes i use the remove all guests cheat on this server. Maybe it messes with the weight of the cars, since it doesn't properly make the peeps disembark from the train, but just removes them instead?

[Gymnasiast]

I'm sure I have seen this numerous times in vanilla. Unless the circumstances are different.

[deurklink]

Well this happens consistently in servers where i have used this cheat. I think it's worth looking into. Re-spawning the cars fixes it, so it seems likely to me the weight of the cars is too much.

[deurklink]

I just checked, and the Remove all guests cheat code doesn't alter the mass of the vehicles, it just removes the peeps from it. Normally when disembarking, in peep_update_ride_sub_state_7(rct_peep * peep), the mass of vehicles gets changed:
vehicle->mass -= peep->mass;
So this way, after using the cheat and the peeps are removed, a filled river rapids boat that had its peeps removed still has the weight of a boat with 8 peeps. If 8 peeps now enter, it has the weight of 16 peeps. If the cheat is used twice this may rise to 24, etc. This is most likely what lead it to become too heavy for the lift hill.
I'm pretty sure this is also what caused a splash boats ride to get stuck on the lift hill in an earlier round in my server. I guess it typically affects rides with a slow lift hill.

[IntelOrca]

I recommend two changes:

• Remove mass when removing peeps from rides
• Set a minimum speed for lift hill so that it can't get stuck.

[deurklink]

@IntelOrca Honestly though, i would recommend to only implement removing the mass when removing peeps from rides. You never know what kinds of rides you may break when putting a minimum speed for lift hill (for example with shuttle type rides that go backwards through a lift hill, where speed is negative).

[deurklink]

Just to confirm, i made this little test Rapids. It ran fastforwarded in hyper speed for many years without any problems. Shortly after i used the remove all guests cheat, it got stuck when a boat filled with peeps tried to climb the lift hill. Same happens with splash boats, except there i have to remove guests twice.
I think this confirms where the problem comes from.

[duncanspumpkin]

I agree with @deurklink there are too many rides that exploit edge cases. We just need to adjust the force removal of peeps cheat.