Light Switch

// =====================================================================
//  Light Switch
//  skimi3d script library
//  https://grid.skimi3d.com/scripts/light-switch
//
//  A lamp you can switch. Touch it and it lights the room, glows, and
//  turns its own shade bright so it looks lit rather than merely
//  illuminating; touch it again and all three go out together.
//
//  The three parts matter. A light with no glow is a room that brightens
//  around a dark lamp. Glow with no light is a lamp that shines on
//  nothing. Doing them separately is how most lamps end up looking
//  wrong.
//
//  Plain LSL.
// =====================================================================


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

// The colour of the light it casts. <1.0, 0.85, 0.6> is a warm bulb,
// <1.0, 1.0, 1.0> is white, <0.6, 0.75, 1.0> is moonlight.
vector COLOUR = <1.0, 0.85, 0.6>;

// How bright, from 0.0 to 1.0.
float INTENSITY = 0.7;

// How far the light reaches, in metres. Up to 20.
float RADIUS = 8.0;

// How quickly it fades with distance, from 0.0 to 1.0. Higher fades
// faster and keeps the light close to the lamp.
float FALLOFF = 0.6;

// Which face of the prim is the shade or the bulb, the part that should
// look lit. -1 means every face. Use the number of a single face if
// only the glass should light up and the metal should not.
integer FACE = -1;

// How much the lit face glows, from 0.0 to 1.0. A little goes a long
// way; 0.15 reads as lit, 0.5 reads as a fault.
float GLOW = 0.15;

// Make the lit face ignore the region's own light, so it stays bright
// at midnight. This is what sells a lamp as switched on.
integer FULLBRIGHT = TRUE;

// Is it already on when it is rezzed?
integer START_ON = TRUE;

// Who may switch it. 0 = everyone, 1 = only the owner, 2 = only people
// wearing the same group tag.
integer WHO_MAY_SWITCH = 0;

// Name of a sound in the lamp's Contents, played on each click. Leave
// empty for a silent switch.
string SOUND = "";
float  VOLUME = 0.4;


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

integer gOn = FALSE;


// One write, not three.
//
// OpenSim gathers object updates and sends them in bundles. Setting the
// light, then the glow, then the brightness in three calls can reach a
// viewer as three separate flickers. Sent together they arrive as one
// change, and the lamp simply comes on.
switchTo(integer on)
{
    float glow = 0.0;
    integer bright = FALSE;

    if (on)
    {
        glow = GLOW;
        bright = FULLBRIGHT;
    }

    list p = [PRIM_POINT_LIGHT, on, COLOUR, INTENSITY, RADIUS, FALLOFF,
              PRIM_GLOW, FACE, glow];

    // PRIM_FULLBRIGHT wants a plain on or off, and only when the lamp
    // is meant to use it at all. A lamp with FULLBRIGHT switched off in
    // the settings should never have its faces touched.
    if (FULLBRIGHT) p += [PRIM_FULLBRIGHT, FACE, bright];

    llSetLinkPrimitiveParamsFast(LINK_THIS, p);

    gOn = on;
}


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


default
{
    state_entry()
    {
        switchTo(START_ON);
    }

    touch_start(integer total)
    {
        key who = llDetectedKey(0);
        if (!maySwitch(who))
        {
            llRegionSayTo(who, 0, "This one is not yours to switch.");
            return;
        }

        if (SOUND != "")
        {
            if (llGetInventoryType(SOUND) == INVENTORY_SOUND)
            {
                llPlaySound(SOUND, VOLUME);
            }
            else
            {
                llOwnerSay("There is no sound called \"" + SOUND + "\" in my Contents.");
            }
        }

        switchTo(!gOn);
    }

    on_rez(integer start)
    {
        // A rezzed copy carries the light state it was taken in, which
        // may not be the one the settings ask for. Say it again.
        switchTo(START_ON);
    }
}