//
// Flight Assist Example
//
// Highlights:
//    - altitude-based assist (lower altitude == less assist, higher == more)
//    - horizontal movement gets relatively less assist than vertical.
//    - HUD color indication of movement mode
//      - brown: not flying (i.e. earth)
//      - green: flying w/ assist
//      - white: hovering w/ assist
//      - black: assist disabled


// gAssistParams enables altitude-based flight assist.   Lower altitudes
// will get less momentum assist so that the client updating overhead
// is less likely to harm controllability.  Plus it's a pain to collide
// with a building at high speed in a damage-enabled area.
//
// see increaseMomentumAssist() for more info
//
list    gAssistParams = [ <1 .1, 100, 200>, <1 .25, 1000, 800>, <1 .4, 10000, -1> ];
float   gInc = 0.1; // The increment to add to the momentum assist parameter on the next control key event
float   gMass;      // current mass (assuming it's constant; can imagine a variable mass assist tho :-) )
integer gMotor = FALSE; // Indicates whether momentum assistance is on
integer gAgentInfo; // A bitmask of the agent/avi current state
integer gReqKeys;  // A bitmask of the control keys required to operate
integer gReqPerms; // A bitmask of the required permissions to operate
key     gWearer;   // UUID of the avi who is wearing this attachment

float   gMomentumAssist = 0; // The current applied momentum assist
float increaseMomentumAssist(vector pos)
{
    integer iii;
    integer len;

    len = llGetListLength(gAssistParams);
    vector aParams;
    for (iii = 0; iii *llGetCameraRot(); // camera rotation leads forward direction; so use it to direct assist
    ret.z = 0;

    return llVecNorm(ret);
}

getPermissions()
{
    integer hasPerms = llGetPermissions();
    integer askPerms = (~hasPerms) & gReqPerms;
    if (hasPerms & PERMISSION_TAKE_CONTROLS)
    {
        llTakeControls(gReqKeys, TRUE, TRUE);
    }
    if (askPerms)
    {
        llRequestPermissions(gWearer, askPerms);
    }
}

gotControlInput(integer held)
{
    gAgentInfo = llGetAgentInfo(gWearer);
        
    if (!(held & gReqKeys))
    {
        if (gAgentInfo & AGENT_FLYING)
        {
            state hover;
        }
    }

    if (gAgentInfo & AGENT_FLYING)
    {
        if (held & gReqKeys)
        {
            vector p = llGetPos();
            vector dir;
            float assist;
            
            assist = increaseMomentumAssist(p);
            
            if (p.z > llGround(ZERO_VECTOR)+50.0)
            {
                llSetBuoyancy(1.0);
            }
            else
            {
                // For some reason, if you are below
                // llGround()+50.0 meters, you will
                // slowly rise to that height if you
                // llSetBuoyancy(1.0).  An avatar can maintain
                // hover below this height w/o assist; so
                // no buoyancy change.
                llSetBuoyancy(0.0);
            }
            
            if (held & CONTROL_FWD)
            {
                dir = getForwardDir();
                // flying too fast horizontally
                // typically makes the avatar
                // uncontrollable since lag is
                // high due to heavy updates;
                // Do a simple reduction of assist
                assist /= 3.0;
            }
            else if (held & CONTROL_BACK)
            {
                dir = -getForwardDir();
                assist /= 3.0;
            }
            else if (held & CONTROL_UP)
            {
                dir = <0,0,1>;
            }
            else if (held & CONTROL_DOWN)
            {
                dir = <0,0,-1>;
            }
                
            llPushObject(gWearer, assist*gMass*dir, ZERO_VECTOR, FALSE);
                
            gMotor = TRUE;
        }
    }
}

onAttach(key avatar)
{
    gWearer = avatar;
    if (gWearer != NULL_KEY)
    {
        getPermissions();
    }
}

default
{
    state_entry()
    {
        gReqKeys = CONTROL_FWD | CONTROL_UP | CONTROL_DOWN | CONTROL_BACK;
        gReqPerms = PERMISSION_TRACK_CAMERA|PERMISSION_TAKE_CONTROLS;
        gMass = llGetMass();
        llSetColor(<0,1,0>, ALL_SIDES);

        // Check if HUD is already attached
        gWearer = llGetOwner(); // for now
        if (llGetAttached() != 0)
        {
            getPermissions();
        }

        llSetTimerEvent(0.1);
    }

    on_rez(integer param)
    {
        llResetScript();
    }
 
    attach(key agent)
    {
        onAttach(agent);
    }
    
    run_time_permissions(integer perm)
    {
        if (perm & PERMISSION_TAKE_CONTROLS)
        {
            llTakeControls(gReqKeys, TRUE, TRUE);
        }
        else
        {
            llWhisper(0, "The flight assist will not operate properly");
        }

        if (!(perm & PERMISSION_TRACK_CAMERA))
        {
            llWhisper(0, "The flight assist will not operate properly");
        }
    }
    
    touch_start(integer num)
    {
        state disabled;
    }

    control(key owner, integer held, integer change)
    {
        gotControlInput(held);
    }
    
    timer()
    {
        gAgentInfo = llGetAgentInfo(gWearer);
        
        if (!(gAgentInfo & AGENT_FLYING))
        {
            state landed;
        }
    }
}

state hover
{
    state_entry()
    {
        llSetColor(<1 ,1,1>, ALL_SIDES);

        gMotor = FALSE;
        gMomentumAssist = 0;
        gInc   = 0.1;
        // adjust a little for lag
        llMoveToTarget(llGetPos(), 0.1);
        vector pos = llGetPos();
        // you can hover unassisted at ground level + 50 meters
        // in fact, if you set buoyancy to 1.0 there, you will slowly
        // rise to ground level + 50 meters
        if (llGround(ZERO_VECTOR)+50.0 , ALL_SIDES);
        llSetTimerEvent(0.3);
    }

    on_rez(integer param)
    {
        llResetScript();
    }
 
    touch_start(integer num)
    {
        state disabled;
    }

    timer()
    {
        gAgentInfo = llGetAgentInfo(gWearer);

        if (gAgentInfo & AGENT_FLYING)
        {
            state default;
        }
    }
}

state disabled
{
    state_entry()
    {
        llSetBuoyancy(0.0);
        llStopMoveToTarget();    // just in case
        llSetColor(<0,0,0>, ALL_SIDES);
    }

    on_rez(integer param)
    {
        llResetScript();
    }
 
    touch_start(integer num)
    {
        state landed;
    }
}

Here is a much requested script that enhances fly. Drop this script in any attachment that does not have a script in it (maybe your prim hair or something). It enhances fly in two ways

1. you can fly as high as you like and you should not drift down (much, it is not perfect).

2. say the word "fly" and it changes into a much faster flying mode. In this mode you can also say "speed 30" to double your speed (or any number, default is 15). say "fly" again, or just stop flying to get out of this mode. One annoying bug, when in fast fly mode you will see "release keys" button. If you push it, your attachment comes off.

// Script Name: Assisted_Flight.lsl
// Author: Ariane Brodie
// Multiple Speed Flight
// Downloaded from : http://www.free-lsl-scripts.com/cgi/freescripts.plx?ID=1318
// This program is free software; you can redistribute it and/or modify it.
// Additional Licenes may apply that prevent you from selling this code
// You must leave any author credits and any headers intact in any script you use or publish.
///////////////////////////////////////////////////////////////////////////////////////////////////
// If you don't like these restrictions and licenses, then don't use these scripts.
//////////////////////// ORIGINAL AUTHORS CODE BEGINS ////////////////////////////////////////////
// Here is a much requested script that enhances fly. Drop this script in any attachment that does not have a script in it (maybe your prim hair or something).
//
//It enhances fly in two ways 1. you can fly as high as you like and you should not drift down (much, it is not perfect). 2. say the word "fly" and it changes into a much faster flying mode. In this mode you can also say "speed 30" to double your speed (or any number, default is 15). say "fly" again, or just stop flying to get out of this mode. One annoying bug, when in fast fly mode you will see "release keys" button. If you push it, your attachment comes off.
//ZeroFlight XLR8
//hacked together script by Burke Prefect, peices from other people's code.
//NOT RESPONSIBLE... FOR ANYTHING
float speed = 15; // this is starting speed.
set_hover() // this keeps you from falling at extreme altitudes. just 'fly' normally. works in either mode.
{
    vector pos = llGetPos();
    float ground = llGround(<0,0,0>);
    if(llGetAgentInfo(llGetOwner()) & AGENT_FLYING)
    {
        if((pos.z > 75) && (pos.z > (ground + 35)))
        { 
            llSetForce(<0,0,9.8> * llGetMass(), FALSE);
        }
        else
        {
            llSetForce(<0,0,0>, FALSE);
        }
    }
    else
        {
            llSetForce(<0,0,0>, FALSE);
        }
}
default // this is where the script starts off. it's not active, it's just waiting for a command.
{
    state_entry()
    {
    key id = llGetOwner();
    llListen(0,"",id,"");
    llSetTimerEvent(.5);
    llReleaseControls();
    }
    timer()
    {
        set_hover();
    }
    
    listen( integer channel, string name, key id, string message ) {
        
        if (message == "fly")
            state freakpack;  
    }
}
    
//// By making 'freakpack' it's own state, we can control it much easier. 
state freakpack
{
    state_entry()
    {
        llSetTimerEvent(.5);
        llListen(0,"",llGetOwner(),"");
        llRequestPermissions(llGetOwner(),PERMISSION_TAKE_CONTROLS);  
    }
    
    // on_rez(integer total_number)
    //{llResetScript();}
    
    touch_start(integer total_number)
    {
        if (llDetectedKey(0) == llGetOwner())
        {
            llReleaseControls();  
            state default;
        }
    }
     timer()
    {
     set_hover();   
    }
    
    run_time_permissions(integer perm)
    {
         if(perm & PERMISSION_TAKE_CONTROLS)
        {
            llTakeControls(CONTROL_FWD|CONTROL_BACK|CONTROL_LEFT|CONTROL_RIGHT|CONTROL_UP|CONTROL_DOWN,TRUE,TRUE);
        }
    }
    
    control(key av, integer level, integer edge)
    {
         if(level & CONTROL_UP)
        {
            llApplyImpulse(<0,0,speed*3>,FALSE);
        }
         if(level & CONTROL_DOWN)
        {
            llApplyImpulse(<0,0,-speed*3>,FALSE);
        }
          if(level & CONTROL_LEFT)
        {
         if(llGetAgentInfo(llGetOwner()) & AGENT_FLYING)
            {   llApplyImpulse(<0,speed,0>,TRUE);}
        }
          if(level & CONTROL_RIGHT)
        {
            if(llGetAgentInfo(llGetOwner()) & AGENT_FLYING)
            {llApplyImpulse(<0,-speed,0>,TRUE);}
        }
         if(level & CONTROL_FWD)
        {
            if(llGetAgentInfo(llGetOwner()) & AGENT_FLYING)
            {llApplyImpulse(,TRUE);}
        }
         if(level & CONTROL_BACK)
        {
            if(llGetAgentInfo(llGetOwner()) & AGENT_FLYING)
            {llApplyImpulse(<-speed,0,0>,TRUE);}
        }
    }
    
    timer()
    {
        if(llGetAgentInfo(llGetOwner()) & AGENT_FLYING)
            set_hover();
        
        else {
            llReleaseControls();  
            state default;
        }
    }
    
    changed(integer change)
    {
        llReleaseControls();  
        state default;
    }
    
    listen(integer channel, string name, key id, string m)
    {
        string ml = llToLower(m);
        list parsed = llParseString2List(ml,[" "],[]);
        if(llList2String(parsed,0) == "speed")
        {
            speed = (float)llList2String(parsed,1);
        }
         if (m=="fly")
        {
            llReleaseControls();
            state default;
        }
    }
}