// simple airplane script example
//Last edited by Andrew Linden on 12-08-2003 at 02:31 PM

// assumes that the root primitive is oriented such that its
// local x-axis points toward the nose of the plane, and its
// local z-axis points toward the top

//if the root primitive of your airplane does not have the same orientation as the whole airplane 
//(i.e. local x-axis = forward, local y-axis = left, local z-axis = up) then the script will not push
//your airplane in the "correct" direction. 
//
//You need to either: 
//
//1. orient your root primitive to agree with the airplane's axes of motion 
//2. pick a different primitive to be the root (one whose local axes agree with those of the airplane's motion) 
//3. use the VEHICLE_REFERENCE_FRAME parameter (this is an advanced topic and is outside the scope of a _simple_ airplane script) 

// control flags that we set later
integer gAngularControls = 0;
integer gLinearControls = 0;

// we keep track of angular history for more responsive turns
integer gOldAngularLevel = 0;

// the linear motor uses an accumulator model rather than keeping track
// of the linear control level history
vector gLinearMotor = <0, 0, 0>;

default
{
    state_entry()
    {
        llSetSitText("Fly");
        llCollisionSound("", .0);

        // the sit and camera placement is very shape dependent
        // so modify these to suit your vehicle
        llSitTarget(<.6, .05, .20>, ZERO_ROTATION);
        llSetCameraEyeOffset(<-10.0, .0, 2> );
        llSetCameraAtOffset(<3, .0, 1> );

        llSetVehicleType(VEHICLE_TYPE_AIRPLANE);

        // weak angular deflection
         llSetVehicleFloatParam(VEHICLE_ANGULAR_DEFLECTION_EFFICIENCY, .1);
         llSetVehicleFloatParam(VEHICLE_ANGULAR_DEFLECTION_TIMESCALE, 1);

        // strong linear deflection
         llSetVehicleFloatParam(VEHICLE_LINEAR_DEFLECTION_EFFICIENCY, 1);
         llSetVehicleFloatParam(VEHICLE_LINEAR_DEFLECTION_TIMESCALE, .2);

        // somewhat responsive linear motor
         llSetVehicleFloatParam(VEHICLE_LINEAR_MOTOR_TIMESCALE, .5);
         llSetVehicleFloatParam(VEHICLE_LINEAR_MOTOR_DECAY_TIMESCALE, 20);

        // somewhat responsive angular motor, but with 3 second decay timescale
         llSetVehicleFloatParam(VEHICLE_ANGULAR_MOTOR_TIMESCALE, .5);
         llSetVehicleFloatParam(VEHICLE_ANGULAR_MOTOR_DECAY_TIMESCALE, 3);

        // very weak friction
         llSetVehicleVectorParam(VEHICLE_LINEAR_FRICTION_TIMESCALE, <1000.0, 1000.0, 1000.0> );
         llSetVehicleVectorParam(VEHICLE_ANGULAR_FRICTION_TIMESCALE, <1000.0, 1000.0, 1000.0> );

         llSetVehicleFloatParam(VEHICLE_VERTICAL_ATTRACTION_EFFICIENCY, .25);  // almost wobbly
         llSetVehicleFloatParam(VEHICLE_VERTICAL_ATTRACTION_TIMESCALE, 1.5);    // mediocre response

         llSetVehicleFloatParam(VEHICLE_BANKING_EFFICIENCY, .4);    // medium strength
        llSetVehicleFloatParam(VEHICLE_BANKING_TIMESCALE, .1);     // very responsive
        llSetVehicleFloatParam(VEHICLE_BANKING_MIX, .95);          // more banking when moving

        // hover can be better than sliding along the ground during takeoff and landing
        // but it only works over the terrain (not objects)
        //llSetVehicleFloatParam(VEHICLE_HOVER_HEIGHT, 3);
        //llSetVehicleFloatParam(VEHICLE_HOVER_EFFICIENCY, .5);
        //llSetVehicleFloatParam(VEHICLE_HOVER_TIMESCALE, 2);
        //llSetVehicleFlags(VEHICLE_FLAG_HOVER_UP_ONLY);

        // non-zero buoyancy helps the airplane stay up
        // set to zero if you don't want this crutch
        llSetVehicleFloatParam(VEHICLE_BUOYANCY, .2);

        // define these here for convenience later
        gAngularControls = CONTROL_RIGHT | CONTROL_LEFT | CONTROL_ROT_RIGHT
                           | CONTROL_ROT_LEFT | CONTROL_DOWN | CONTROL_UP;
        gLinearControls = CONTROL_FWD | CONTROL_BACK;

        llSetStatus(STATUS_PHYSICS, TRUE);
    }

    changed(integer change)
    {
        if (change & CHANGED_LINK)
        {
            key agent = llAvatarOnSitTarget();
            if (agent)
            {
                if (agent != llGetOwner())
                {
                    // only the owner can use this vehicle
                    llSay(0, "You aren't the owner");
                    llUnSit(agent);
                    llPushObject(agent, <0,0,10>, ZERO_VECTOR, FALSE);
                }
                else
                {
                    // clear linear motor on successful sit
                    gLinearMotor = <0, 0, 0>;
                     llSetVehicleVectorParam(VEHICLE_LINEAR_MOTOR_DIRECTION, gLinearMotor);

                    //llSetStatus(STATUS_PHYSICS, TRUE);
                     llSetVehicleFloatParam(VEHICLE_LINEAR_FRICTION_TIMESCALE, 1000.0);
                     llSetVehicleFloatParam(VEHICLE_ANGULAR_FRICTION_TIMESCALE, 1000.0);
                    llRequestPermissions(agent, PERMISSION_TRIGGER_ANIMATION | PERMISSION_TAKE_CONTROLS);
                }
            }
            else
            {
                // stop the motors
                gLinearMotor = <0, 0, 0>;
                 llSetVehicleVectorParam(VEHICLE_LINEAR_MOTOR_DIRECTION, gLinearMotor);
                 llSetVehicleVectorParam(VEHICLE_ANGULAR_MOTOR_DIRECTION, gLinearMotor);

                // use friction to stop the vehicle rather than pinning it in place
                //llSetStatus(STATUS_PHYSICS, FALSE);
                 llSetVehicleFloatParam(VEHICLE_LINEAR_FRICTION_TIMESCALE, 1);
                 llSetVehicleFloatParam(VEHICLE_ANGULAR_FRICTION_TIMESCALE, 1);

                // driver is getting up
                llReleaseControls();
                llStopAnimation("motorcycle_sit");
            }
        }

    }

    run_time_permissions(integer perm)
    {
        if (perm)
        {
            llStartAnimation("motorcycle_sit");
            llTakeControls(gAngularControls | gLinearControls, TRUE, FALSE);
        }
    }

    control(key id, integer level, integer edge)
    {
        // only change linear motor if one of the linear controls are pressed
        vector motor;
        integer motor_changed = level & gLinearControls;
        if (motor_changed)
        {
            if(level & CONTROL_FWD)
            {
                if (gLinearMotor.x < 0)
                {
                    gLinearMotor.x = 0;
                }
                else if (gLinearMotor.x < 30)
                {
                    gLinearMotor.x += 5;
                }
                motor_changed = TRUE;
            }
            if(level & CONTROL_BACK)
            {
                if (gLinearMotor.x > 0)
                {
                    gLinearMotor.x = 0;
                }
                else if (gLinearMotor.x > -30)
                {
                    gLinearMotor.x -= 5;
                };
                motor_changed = TRUE;
            }
             llSetVehicleVectorParam(VEHICLE_LINEAR_MOTOR_DIRECTION, gLinearMotor);
        }

        // only change angular motor if the angular levels have changed
        motor_changed = (edge & gOldAngularLevel) + (level & gAngularControls);
        if (motor_changed)
        {
            motor = <0,0,0>;
            if(level & (CONTROL_RIGHT|CONTROL_ROT_RIGHT))
            {
                // add roll component ==> triggers banking behavior
                motor.x += 10;
            }
            if(level & (CONTROL_LEFT|CONTROL_ROT_LEFT))
            {
                motor.x -= 10;
            }
            if(level & (CONTROL_UP))
            {
                // add pitch component ==> causes vehicle lift nose (in local frame)
                motor.y -= 8;
            }
            if(level & (CONTROL_DOWN))
            {
                motor.y += 8;
            }
             llSetVehicleVectorParam(VEHICLE_ANGULAR_MOTOR_DIRECTION, motor);
        }
        // store the angular level history for the next control callback
        gOldAngularLevel = level & gAngularControls;
    }
}