Second Life Physics Scripting - Pinball #23 - llRez and llDie

The next feature is to remove the ball when it hits the back wall and then to have it respawn when the user presses the page up key.

The first problem is that the ball has to remove itself. There doesn't seem to be a way to have a script remove another object.

I first set out to have the ball remove itself when it had a collision with the back wall. The problem with this is that the back wall is linked and the collision name had "pinball 1.4" which may change over time and that this collision only occured once when the ball was first placed on the table since it is all one linked set.

The next solution is to send a message to the ball when the back wall is hit and I did this with the chat system llSay.

        if (llDetectedName(0) == "ball")
        {
            ...
            //llPushObject(llDetectedKey(0), pos3, <0,0,0>, FALSE);
            
            llSay(1296,"byebye");

        }

This was as simple as removing the push and adding the llSay. The next step is to have the ball listen for the message.

integer listen_handle;

default
{
    state_entry()
    {
        listen_handle = llListen( 1296, "backwall", NULL_KEY, "" );        
    }
    listen(integer channel, string name, key id, string message)
    {

        //llOwnerSay("ball listen, heard = "+name);
        if  ((channel==1296) && (llToLower(message) == "balldied"))
        {
            //llOwnerSay("Ball died!");
            llDie();
        }
    }
    
}

The ball is listening for the object backwall to say "byebye" on channel 1296. At first I thought this would be too slow, but it seems very quick and the ball goes away before bouncing back onto the table.

Make sure you keep a copy of the ball in your inventory because when it dies you don't want to have to recreate the scripts over and over.

The next step is the spawning of the ball (llRez) when the user presses the page up key. I did this in the PayAndKeyboard script in root table object. This is the same script that handles the key presses to move the puck flipper.

RezBall()
{
    if (!in_play)
    {
        in_play = TRUE;
        
        // find the size of the this table
        vector sz = llList2Vector(llGetPrimitiveParams([PRIM_SIZE]),0);
        
        vector pos = llGetPos();
        //llOwnerSay("pos = "+(string)pos);
        vector up = llVecNorm(pos * llGetLocalRot());
        up = up * ((sz.z/2) + 0.21); // add the size of the ball
        //llOwnerSay("up = "+(string)up);
        
        pos = pos + up;
        //llOwnerSay("rez pos = "+(string) pos);
        
        llRezObject("ball",pos,<0,0,0>,ZERO_ROTATION,0);
    }
}

I wrote a separate function for the rez ball. This still has problems as I think it rezes the ball too low on the table, but it has a neat effect in that the ball sort of oozes out of the table. It needs looking into at some point.

Next is the event to rez the ball.

  control(key id, integer held, integer change)
    {
        ... puck flipper code

        // page up key
        if ((held&CONTROL_UP) && (change&CONTROL_UP))
        {
            if (!in_play)
                {
                 llSay(0," here we go!!!");
                }
            RezBall();
        }
    }

Then we have to have a way to reset the in_play flag so the user can press the "page up" key again and have the ball rez. This is as simple as adding the listen method the same as we used for the ball. Both the ball and this PayAndKeyboard script will both hear the same message from the backwall.

    state_entry()
    {

        listen_handle = llListen( 1296, "backwall", NULL_KEY, "" );
        llSetTimerEvent(30);

        ... other initialization code
    }

    listen(integer channel, string name, key id, string message)
    {
        if  ((channel==1296) && (llToLower(message) == "balldied"))
        {
            llSay(0,"Oops, drain. Press 'Page Up' to start another ball.");
            in_play = FALSE;
            llSetTimerEvent(30);
        }
    }

As you can see I also added some timer events. This is so the table is actually doing something when people first walk up to it. A teaser to get people interested. 30 seconds after every drain, then timer goes off. If the ball isn't already in play (because someone pushed page up), then a new ball is spawned.

    timer()
    {
        if (!in_play)
        {
            llSay(0,"Autoplay starting");
            RezBall();
        }
        llSetTimerEvent(0);
    }