Library: Low lag sensor script to trigger when avatar comes close

Every 5 seconds, this script looks for an avatar within 15 meters. If detected, a command is whispered to a sign to turn on, and an invitation is said on chat channel 0. It will keep scanning for avatars within 15 meters every 5 seconds, but will not chat or turn on sign while somebody is nearby. Once the avatar leaves (greater than 15 meters away), the sign turns off, ready to turn on when the next avatar comes by.

// ------------------------------------------
// Game Attraction Script
// By Mr Greggan
// 02-24-2008

// Public Domain.... have fun with this script!

integer SomebodyNear = 0;

default
{
state_entry()
{
llSetTimerEvent(5.0);
}

timer()
{
llSensor("",NULL_KEY,AGENT,15,PI);
}

sensor(integer num_detected)
{
if (SomebodyNear == 0)
{
llWhisper(23, "Sign_On"; // Turn on the sign advertising this game
llSay(0, "Hello, come try this game!";
SomebodyNear = 1;
}
}

no_sensor()
{
llWhisper(23, "Sign_Off"; // Turn off the sign advertising this game
SomebodyNear = 0;
}
}

// ------------------------------------------

Why not to use llSensorRepeat instead of timer?

perhaps to limit av detection to the current sim for edge parcels (sensor repeat will go across borders, sensor won't) or eliminate the related bug where agents on the sim edge get reported regardless of distance. or perhaps OP didn't know it was available.

Those are all good reasons to avoid the llSensorRepeat. Mainly, I didn't know too much about that function. I just wanted to keep this simple and low lag.

I did figure out that this section:

sensor(integer num_detected)
{
if (SomebodyNear == 0)
{
llWhisper(23, "Sign_On"; // Turn on the sign advertising this game
llSay(0, "Hello, come try this game!";
SomebodyNear = 1; // THIS SHOULD BE FIRST
}
}

Works better with this change:

{
SomebodyNear = 1; // LIKE THIS
llWhisper(23, "Sign_On"; // Turn on the sign advertising this game
llSay(0, "Hello, come try this game!";
}


A minor point, but it makes for better coding I think.

you can also speed up you logical processing by changing the 'somebodyNear' boolean to 'nobodysAround'

then your if statment in the sensor event could be
if (nobodysAround){
nobodysAround = !nobodysAround;
//-- etc
}


of course you should probably have similar logic in your no sensor, to keep it from spamming the off command if there's not any traffic for awhile (in which case it doesn't matter which logical order you use, because one teset will always be (boolean) and one will always be (!boolean)... 'boolean' should go in the place that's most likely to occur during a given time, or default to the active if it's about equal)

if you put the sensor in the sign, you can use llMessageLinked rather than llSay and llListen.

If it's just a colour/alpha change to light up the sign.. why even bother with a message.. just change the settings on the linked prims~

The irony is that it is labeled "Low lag sensor" but everyone knows that it WILL be used to trigger scripts that will lag the shit out of you.

rofl