[Abagail]

First and foremost, you can use the GetPlayerSurfingVehicleID function to check if the player is surfing on the roof. Example of checking if someone is:
1. Surfing on any car:

pawn Код:

if(GetPlayerSurfingVehicleID(playerid) != INVALID_VEHICLE_ID)
{
     // do things here
}

2. Surfing on a specific car

pawn Код:

if(GetPlayerSurfingVehicleID(playerid) == vehicleid)
{
     // do something here
}

Secondly, you can use the SetPlayerVelocity(or even SetPlayerPos) function to move the player off of the car. For example, you can slap the player into the air.

pawn Код:

new Float: x, Float: y, Float: z;
GetPlayerPos(playerid, x, y, z);
SetPlayerPos(playerid, x, y, z + 6.0);