Alter Ego NPC

///////////////////////////////////////////////////////////////////////////
//  Copyright (C) Wizardry and Steamworks 2012 - License: GNU GPLv3      //
//  Please see: http://www.gnu.org/licenses/gpl.html for legal details,  //
//  rights of fair usage, the disclaimer and warranty conditions.        //
///////////////////////////////////////////////////////////////////////////

//////////////////////////////////////////////////////////
//                  CONFIGURATION                       //
//////////////////////////////////////////////////////////

// Specifies the radius of the circle in which the NPC
// will travel in.
float MOVEMENT_RANGE = 5.0;
// How often to check that the NPC has reached a
// waypoint.
float POLL_TIME = 1;
// Set this to the name of the animation for the walk
// equence. This animation has to be placed in the
// same primitive as this script.
string ANIMATION_WALK="Walk";
// Set this to the name of the animation for the stand
// sequence. This animation has to be placed in the
// same primitive as this script.
string ANIMATION_STAND="Stand";
// How much time, in seconds, does a standing animation
// cycle take?
float STANDING_ANIMATION_CYCLE_TIME = 20;
// How many cycles to wait, randomly?
integer STANDING_ANIMATION_CYCLES = 3;

///////////////////////////////////////////////////////////////////////////
//                              INTERNALS                                //
///////////////////////////////////////////////////////////////////////////

vector wasCirclePoint(float radius) {
    float x = llPow(-1, 1 + (integer) llFrand(2)) * llFrand(radius*2);
    float y = llPow(-1, 1 + (integer) llFrand(2)) * llFrand(radius*2);
    if(llPow(x,2) + llPow(y,2) <= llPow(radius,2))
        return <x, y, 0>;
    return wasCirclePoint(radius);
}

// Vector that will be filled by the script with
// the initial starting position in region coordinates.
vector iPos = ZERO_VECTOR;
// Storage for destination position.
vector dPos = ZERO_VECTOR;
// Key of the NPC
key npcKey = NULL_KEY;

default {
    state_entry() {
        llSetStatus(STATUS_PHANTOM, TRUE);
        osNpcRemove(llGetObjectDesc());
        iPos = llGetPos();
        osAgentSaveAppearance(llGetOwner(), "appearance");
        npcKey = osNpcCreate("Alter", "Ego", iPos, "appearance");
        llSetObjectDesc(npcKey);
        // It seems that 1 second is a magic wait-time that must
        // separate the osNpcCreate from other commands or else
        // the NPC rezzes as a cloud.
        llSetTimerEvent(1);
    }
    timer() {
        llSetTimerEvent(0);
        llSay(0,"load appearance");
        osNpcLoadAppearance(npcKey, "appearance");
        state wander;
    }
}

state wander
{
    state_entry() {
        llSay(0,"wandering");
        dPos = iPos + wasCirclePoint(MOVEMENT_RANGE);
        osNpcPlayAnimation(npcKey, ANIMATION_WALK);
        osNpcMoveToTarget(npcKey, dPos, OS_NPC_NO_FLY);
        llSetTimerEvent(POLL_TIME);
    }

    timer() {
        // Another magic value (2), it seems that even on flat ground
    // the NPC never really reaches the destination position.
    // Instead, it reaches some point that is always (experimentally)
    // smaller than 2 meters. Hence the comparison.
        if (llVecDist(osNpcGetPos(npcKey), dPos) > 2) return;
        osNpcStopAnimation(npcKey, ANIMATION_WALK);
        osNpcPlayAnimation(npcKey, ANIMATION_STAND);
        llSetTimerEvent(0);
        state wait;
    }
}

state wait {
    state_entry() {
        llSetTimerEvent(STANDING_ANIMATION_CYCLE_TIME * 1+llFrand(STANDING_ANIMATION_CYCLES-1));
    }
    timer() {
        llSetTimerEvent(0);
        osNpcStopAnimation(npcKey, ANIMATION_STAND);
        state wander;
    }
}