mart3p opened the ticket and wrote:

There is an error in the function GetVehicleTrackDir in vehicle.c that often returns incorrect values for road vehicles. This function is used when pathfinding to depots by YAPF and NPF. This bug is in the trunk code but also in 0.4.7, maybe it should also be fixed for 0.4.8.

To reproduce the error:-

1. Ensure YAPF is selected for road vehicles or NPF is on.
2. Build 2 road vehicle stops and a depot with a number of bends and T-junctions between them.
3. Set a road vehicle to run between the stops.
4. Click on the vehicle's 'Goto Depot' button as it is entering a bend or a T-junction. The message "Can't send vehicle to Depot... Unable to find local depot" often occurs even when there is an easily reachable depot within a few tiles

Cause of error:-
The line:
return DiagdirToDiagTrackdir(DirToDiagDir(v->direction));
is causing the problem. When a vehicle is entering or exiting a bend, using v->direction to determine the vehicle's TrackDir does not work, as the direction the vehicle is facing is not a valid TrackDir for the tile that the vehicle is on. For example, when first entering a road bend tile the vehicle is pointing across the tile, but there is no possible track across the tile in that direction.

Fix:-
The vehicle's TrackDir can easily be determined as in is held by vehicle->u.road.state while the vehicle is moving along a normal road. Note, vehicle->u.road.state holds different information while the vehicle is in a road stop or depot, but GetVehicleTrackDir already treats these as a separate cases.

The only slight difficulty with this is that a road vehicle's vehicle->u.road.state uses the unused values of TrackDir (values 0x6, 0x7, 0xE and 0xF) to indicate that the vehicle is turning around (through 180°). In these cases the existing code (using vehicle->direction to determine the TrackDir) can still be used.

The attached patch contains the necessary change to correct this bug.

Attachments

• RV_Find_Depot_Bugfix_r5510.patch (0.71 KiB)

Reported version: 0.4.7
Operating system: All

This issue was imported from FlySpray: https://bugs.openttd.org/task/249