trams/trains are blocked by their own trailer.

[kianzarrin]

This is also a vanilla problem: when segment is updated or TMPE rules are updated, the leading vehicle will go a little bit backwards (because it will reset simulation speed data) while the trailers will not (they will stop immediately). if the vehicle is going fast enough it can get behind its own trailer and get blocked by it.

https://user-images.githubusercontent.com/26344691/168418804-592f2b8c-1d33-4079-a765-a7cde4bcc51c.mp4

https://cdn.discordapp.com/attachments/545066674605391882/965713435935506512/2022-04-18_23-39-26.mkv

Solutions:

• leading vehicle must ignore its own trailer in collision checks.
• trailers must also reset their simulation frame data.

[kianzarrin]

Collision check takes place in CarAI.CheckOtherVehicle().

private static ushort CheckOtherVehicle(ushort vehicleID, ref Vehicle vehicleData, ref Vehicle.Frame frameData, ref float maxSpeed, ref bool blocked, ref Vector3 collisionPush, float maxBraking, ushort otherID, ref Vehicle otherData, Vector3 min, Vector3 max, int lodPhysics)
{
    if (otherID != vehicleID && vehicleData.m_leadingVehicle != otherID && vehicleData.m_trailingVehicle != otherID)

The if condition above only checks one trailer. we need a prefix that checks all trailers.

[krzychu124]

@kianzarrin watch carefully the clip. Trailers stop immediately, they don't collide with the leading vehicle. It's the leading vehicle moving back and forth

[kianzarrin]

yes. but if I disable collision with its own trailer then the tram can get un-stuck.

[kianzarrin]

it had nothing to do with collision. train/tram was going backward because targetpos was updated.