// =====================================================================
//  Sliding Door
//  skimi3d script library · https://grid.skimi3d.com/scripts/sliding-door
//
//  A door that slides aside when touched and slides back on its own.
//  The barn door, the shop shutter, the lift door, the pocket door that
//  disappears into the wall.
//
//  It is the sister of Swing Door and takes the same shape, so once you
//  have set up one you know the other. The difference is that this one
//  moves in a straight line and never turns.
//
//  Plain LSL. Works on a lone prim and on a child prim in a linkset.
// =====================================================================


// ---------------------------------------------------------------------
//  Settings
// ---------------------------------------------------------------------

// Which way it slides, in the door's own body. <1.0, 0.0, 0.0> slides
// it along its own X. If the door disappears into the floor instead of
// into the wall, this is the line to change.
vector DIRECTION = <1.0, 0.0, 0.0>;

// How far it slides. 1.0 means "its own width along that direction",
// so the door ends up exactly beside the hole it was filling. Use 0.9
// if you want it to stay slightly overlapping, or a plain number of
// metres by setting IN_METRES below.
float DISTANCE = 1.0;

// Read DISTANCE as metres instead of as a fraction of the door.
// FALSE is the friendlier setting: a door set up as a fraction still
// works after you resize it.
integer IN_METRES = FALSE;

// How long the slide takes, in seconds. 0.0 snaps it aside.
float SLIDE_TIME = 1.2;

// Seconds it stays open before sliding back. 0.0 means it stays open
// until someone touches it again.
float AUTO_CLOSE = 8.0;

// Who may open it.
//   0 = everyone
//   1 = only the owner
//   2 = only people wearing the same group tag as the door
integer WHO_MAY_OPEN = 0;

// Sounds. Drop a sound into the door's Contents and write its name
// here. Leave empty for a silent door.
string SOUND_OPEN = "";
string SOUND_SHUT = "";
float  VOLUME     = 0.5;


// ---------------------------------------------------------------------
//  Everything below here is the machinery
// ---------------------------------------------------------------------

// One step every tenth of a second, and not one step more.
//
// OpenSim gathers object updates and sends them out in bundles, about
// eleven times a second. Writing the door's position more often than
// that does not make the slide smoother, because the extra positions
// never reach anyone's viewer. It only costs the region work. If the
// slide looks choppy, give it more TIME, not more steps.
float STEP = 0.1;

integer gOpen   = FALSE;   // is it standing open right now?
integer gMoving = FALSE;   // mid-slide, ignore further touches
vector   gShutPos;         // where it sits when shut
rotation gShutRot;         // how it sits when shut
vector   gTravel;          // the whole journey, in the parent's frame


// Put the door at some fraction of its travel. 0.0 is shut, 1.0 is
// fully open.
place(float f)
{
    // Always measured from the shut position, never from the last step.
    // A door that added a little each time would walk away from its
    // frame over an afternoon of use, a few millimetres at a time.
    llSetLinkPrimitiveParamsFast(LINK_THIS, [PRIM_POS_LOCAL, gShutPos + gTravel * f]);
}


slide(integer open)
{
    gMoving = TRUE;

    integer steps = (integer)(SLIDE_TIME / STEP);
    if (steps > 1)
    {
        integer i;
        for (i = 1; i < steps; ++i)
        {
            float f = (float)i / (float)steps;
            if (!open) f = 1.0 - f;
            place(f);
            llSleep(STEP);
        }
    }

    // Always land exactly on the end state, so a door left on the
    // second-to-last step cannot sit a finger's width ajar.
    float end = 0.0;
    if (open) end = 1.0;
    place(end);

    gOpen   = open;
    gMoving = FALSE;
}


play(string name)
{
    if (name == "") return;

    if (llGetInventoryType(name) != INVENTORY_SOUND)
    {
        // The owner can fix this. A visitor cannot, and does not need
        // to hear about it.
        llOwnerSay("There is no sound called \"" + name + "\" in my Contents.");
        return;
    }

    llPlaySound(name, VOLUME);
}


integer mayOpen(key who)
{
    if (WHO_MAY_OPEN == 1) return who == llGetOwner();
    if (WHO_MAY_OPEN == 2) return llSameGroup(who);
    return TRUE;
}


default
{
    state_entry()
    {
        // The door learns its shut position from wherever it stands at
        // this moment. Put it where it belongs BEFORE you drop the
        // script in.
        list p = llGetLinkPrimitiveParams(LINK_THIS, [PRIM_POS_LOCAL, PRIM_ROT_LOCAL]);
        gShutPos = llList2Vector(p, 0);
        gShutRot = llList2Rot(p, 1);

        // DIRECTION is given in the door's own body, so that a door
        // mounted at an angle still slides along itself rather than
        // along the region's axes. Turned into the parent's frame here,
        // once, because that is the frame we can actually set.
        vector dir = llVecNorm(DIRECTION);
        float  far = DISTANCE;

        if (!IN_METRES)
        {
            // A fraction of the door, measured along the direction it
            // travels. This is what keeps the setting true after a
            // resize: a door twice as wide slides twice as far.
            vector s = llGetScale();
            vector along = <dir.x * s.x, dir.y * s.y, dir.z * s.z>;
            far = DISTANCE * llVecMag(along);
        }

        gTravel = (dir * far) * gShutRot;

        gOpen   = FALSE;
        gMoving = FALSE;
        llSetTimerEvent(0.0);
    }

    touch_start(integer total)
    {
        if (gMoving) return;

        key who = llDetectedKey(0);
        if (!mayOpen(who))
        {
            llRegionSayTo(who, 0, "This door does not open for you.");
            return;
        }

        llSetTimerEvent(0.0);

        if (gOpen)
        {
            play(SOUND_SHUT);
            slide(FALSE);
            return;
        }

        play(SOUND_OPEN);
        slide(TRUE);

        if (AUTO_CLOSE > 0.0) llSetTimerEvent(AUTO_CLOSE);
    }

    timer()
    {
        llSetTimerEvent(0.0);
        if (!gOpen) return;

        play(SOUND_SHUT);
        slide(FALSE);
    }

    on_rez(integer start)
    {
        // A rezzed copy stands somewhere new, so its idea of shut is
        // worthless. Learn it again.
        llResetScript();
    }

    changed(integer what)
    {
        // Linking or unlinking changes what a local position means, so
        // the door has to measure itself again. Only when it is shut and
        // still, though: reset it mid-slide and it would take its
        // half-open position for the shut one and never close properly.
        if (what & CHANGED_LINK)
        {
            if (!gOpen && !gMoving) llResetScript();
        }
    }
}