eps megcsinálnád ugy ezt hogy csak akkor ha pl a jump[playerid] = 1; -el csak akkor lehesssen h-val ugrani ha 0-valegyenlöre akkor ne csináljon semit?:S
 

#include a_samp
new bool:jump[MAX_PLAYERS];
#define COLOR_RED 0xFF0000AA
#define COLOR_GREEN 0x33AA33AA
JumpVeh(vid, Float:dis = 0.5)
{
new Float:T[3];
GetVehicleVelocity(vid, T[0], T[1], T[2]);
SetVehicleVelocity(vid, T[0], T[1], floatadd(T[2],dis));
return 1;
}
public OnPlayerKeyStateChange(playerid, newkeys, oldkeys)
{
    if (newkeys & 2 && GetPlayerState(playerid)-1)
    {
        if(jump[playerid] == true) return JumpVeh(GetPlayerVehicleID(playerid),0.2);
    }
    return 1;
}
// innentol ez nem fontos
public OnPlayerConnect(playerid) return jump[playerid] = true;
public OnPlayerCommandText(playerid, cmdtext[])
{
if (strcmp(\"/jumpon\", cmdtext, true, 10) == 0)
{
if(jump[playerid] == true) return SendClientMessage(playerid, COLOR_RED,\"A jump már be van kapcsolva\");
    jump[playerid] = true;
        SendClientMessageToAll(COLOR_RED,\"jump bekapcsolva\");
   return 1;
}
if (strcmp(\"/jumpoff\", cmdtext, true, 10) == 0)
{
if(jump[playerid] == false) return SendClientMessage(playerid, COLOR_RED,\"A jump már ki van kapcsolva\");
        jump[playerid] = false;
        SendClientMessageToAll(COLOR_GREEN,\" jump kikapcsolva\");
return 1;
}
return 1;
}