[Nanory]

After 30 Minites thinking I have now the solution to get the real position of the Petrolcap from the vehicle:
I lookat at the function:

pawn Код:

stock GetXYInFrontOfPlayer(playerid, &Float:x, &Float:y, Float:distance)
{
    new Float:a;
    GetPlayerPos(playerid, x, y, a);
    GetPlayerFacingAngle(playerid, a);
    if (GetPlayerVehicleID(playerid))
    {
        GetVehicleZAngle(GetPlayerVehicleID(playerid), a);
    }
    x += (distance * floatsin(-a, degrees));
    y += (distance * floatcos(-a, degrees));
}

if I now take the angle of the player and add 180° i get:

pawn Код:

stock GetXYInBehindOfPlayer(playerid, &Float:x, &Float:y, Float:distance)
{
    new Float:a;
    GetPlayerPos(playerid, x, y, a);
    GetPlayerFacingAngle(playerid, a);
    if (GetPlayerVehicleID(playerid))
    {
        GetVehicleZAngle(GetPlayerVehicleID(playerid), a);
    }
    a+=180;
    x += (distance * floatsin(-a, degrees));
    y += (distance * floatcos(-a, degrees));
}

The only thing i have to do now is to add to the angle "a+=180" an other angle, which i get if I calculate the Angle with the tangent of OffSetY div OffSetX... Furthermore I change playerid to vehicleid because a player hasn't a Petrolcap :P
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The finish Function looks like this:

pawn Код:

stock GetXYZOfOffSetPositions(vehicleid,Float:OffSetX,Float:OffSetY,Float:OffSetZ,&Float:x, &Float:y, &Float:z)
{
    new Float:a,Float:distance;
    GetVehiclePos(vehicleid, x, y, z);
    GetVehicleZAngle(GetPlayerVehicleID(playerid), a);
    a-=180.0+atan(OffSetY,OffSetX);
    distance = floatsqroot(floatpower(OffSetX,2)+floatpower(OffSetY,2))
    x += (distance * floatsin(-a, degrees));
    y += (distance * floatcos(-a, degrees));
    z += OffSetZ;
}

Now it's really easy to use... Here is an Example

Код:

400 petrolcap -1.10 -2.06 -0.07

pawn Код:

public OnUnoccupiedVehicleUpdate(vehicleid, playerid, passenger_seat)
{
    if(GetVehicleModel(vehicleid) == 400)
    {
        new Float:LookingPos[3];
        GetXYZOfOffSetPositions(vehicleid,-1.10,-2.06,-0.07,LookingPos[0], LookingPos[1], LookingPos[2]);
        // Now you only have to check if the player looks at the Position LookingPos[0], LookingPos[1], LookingPos[2]
        // If the player do this, you know that he aims at the petrolcap ...
    }
    return 1;
}