Open Prim Animator/Touch Ping Pong

//!  @brief This is a utility script for OPA for cases when animation frames are meant to be viewed sequentially in both forward and "reverse".
/**
*    @author SignpostMarv Martin
*/

//!  The number of animation frames
integer count;

//!  if TRUE then the "ping pong" is in effect and should not be interupted.
integer running=FALSE;

//!  interval between animation frames
float interval = 1.0;

//!  
integer at=1;
integer mod=1;
default{
    state_entry() {
        llMessageLinked(LINK_ROOT, -1, "XDrecordedSnapshots", NULL_KEY); // get the number of animation frames from the core OPA script.
    }

    link_message(integer s, integer n, string m, key i){
        if(m == "XDrecordedSnapshots" && n >= 0){
            count = n; // update the number of animation frames
        }
    }

    touch_start(integer t){
        if(!running){ // if we're not doing the "ping-pong",
            running = TRUE; // set the flag to TRUE
            llSetTimerEvent(interval); // then set the timer event away.
        }
    }

    timer(){
        if(count <= 0){
            llSetTimerEvent(0); // stop the timer
        }else{
            at += mod; // add the modifier (which may be a negative integer)
            if(at >= count){ // if we're at the end of the "ping-pong", 
                mod = -1; // change the mod to negative 1 in preparation of reversing the animation
                llSetTimerEvent(0); // turn off the timer
                running = FALSE; // set the running flag to FALSE so a user can touch the script.
            }else if(at <= 1){ // if we're at the end of the "pong-ping",
                mod = 1; // change them od to positive one in preparation of running the animation
                llSetTimerEvent(0); // turn off the timer.
                running = FALSE; // set the running flag to FALSE so a user can touch the script.
            }
            llMessageLinked(LINK_ROOT, at, "XDshow", NULL_KEY); // instruct the core OPA script to change the displayed animation frame.
        }
    }
}