Vehicle Problem: Passenger sits, vehicle resets.

Okay, so I'm making a boat. It's a pretty daunting task, to be honest. I started out with one of the well worn freebie boat scripts, then began tweaking physics settings, adding features, sounds, etc etc.

So now the script has quite a bit going on with it. But in iit's heart, it's still that basic boat script.

When the linkset changes.. if there's a non-NULL_KEY on the sit target (someone is sitting), it does a test. If the sitter is the owner, the boat script goes into active mode (and plays a little sound to let me know it's ready to go). If the sitter on the sit target is NOT the owner, it boots them (standard behaviour). If there's NULL_KEY on the sittarget, then the vehicle shuts down.

So here's the problem. I added some additional seats. They're all pretty basic in themselves. Sit targets of their own.. the sit scripts seem to "know" when an avatar is sitting on that given prim.. and it acts accordingly (plays an animation for them).

BUT the main boat script is also aware that "someone sat on the boat".. and when the Owner is already seated.. it polls the linkset and says "hey, the owner is sitting on the sit target" so it starts the vehicle... again.

Is there some sort of standard practice for solving this problem? Is it as simple as adding a flag "driverSitting = TRUE".. when the driver is first detected and clearing it when the driver leaves? Or is there some, more elegant method by which to ignore the sitters on child prims?

(P.S... is it REALLY still neccessary to set STATUS_BLOCK_GRAB in every prim of the linkset?)

The normal way to do this is to use states. When the vehicle's just sitting there waiting for a driver you have a nice simple state that just detects a sitter and does the permissions checks and then switches state to the active state. In the active state you take controls for the driver, and watch run_time_permissions. When the driver stands up you'll lose PERMISSION_TAKE_CONTROLS, then you go non-physical and switch back to the default state waiting for a new driver.

or w/o states

//-- in globals
integer gIntEmpty = TRUE;

//-- in changed
if (llAvatarOnSitTarget() == llGetOwner()){
  if (gIntEmpty)
  gIntEmpty = FALSE;
  //-- start boat
  }
}else{
  llUnsit( llAvatarOnSitTarget );
  gIntEmpty = TRUE;
  //-- stop boat
}

That's still using states, you're just implementing the states by hand instead of letting LSL do it for you. You can add a state variable and add a check in all the events to see if you're in the right state or not, but this is a situation where explicit states are a clear winner. The behavior of a vehicle when it's being driven and when it's not are completely different. The code is simpler because you can completely eliminate the events you don't care about in the resting state.

when using multiple states, in the active state, you can use the changed link test that's used in most pose scripts that i've seen.

changed(integer change)
{
if(change & CHANGED_LINK)
{
if(llAvatarOnSitTarget() == NULL_KEY){llResetScript();}
}
}

there's no else in there to make it do anything if the owner is still seated, so it should just continue running as normal