Scripting Tutorial-08

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Scripting Lesson #8 - Held September 1st, 2018 at Sandbox Plaza by Fu Barr

    Fu's basic light switch
    - turn-off-the-lamp timeout
    - expanded setup
    - basic on/off toggle
integer DEBUG = TRUE;
integer dialog_listen_id;
float   LAMP_TIMEOUT = 5.0;
list    lamps;
list    colours_names = ["red", "blue", "green"];
list    colours_rgb   = [<1.0, 0, 0>, <0, 0, 1.0>, <0, 1.0, 0>]; 
float   colours_glow  = 0.20;
set_lamps(string colour_name) {
    vector  rgb;
    float   glow;
    if(colour_name == "none") {
        rgb = <1,1,1>;
        glow = 0.0;
    } else {
        integer id = llListFindList(colours_names, [colour_name]);
        if(id > -1) {
            rgb  = llList2Vector(colours_rgb, id);
            glow = colours_glow;
    integer i   = 0;
    integer end = llGetListLength(lamps);
    while(i < end) {
        llSetLinkPrimitiveParamsFast(llList2Integer(lamps, i), 
            // the UUID here is the OSgrid specific one for 'Blank Texture'
              PRIM_TEXTURE,     ALL_SIDES, "5748decc-f629-461c-9a36-a35a221fe21f", <1,1,0>, <0,0,0>, 0,
              PRIM_COLOR,       ALL_SIDES, rgb, 1.0, 
              PRIM_GLOW,        ALL_SIDES, glow ]
default {
    state_entry() {
        llOwnerSay("running: " + llGetScriptName());
        // 0. setup lamps
        integer i   = 1;    // linked prims are numbered from 1
        integer end = llGetNumberOfPrims();
        while(i <= end) {
            if(llGetLinkName(i) == "lamp") {
                lamps += i;
        if(DEBUG){llOwnerSay(llDumpList2String(lamps, ","));}
        // 1. generate random DIALOG_CHANNEL
        DIALOG_CHANNEL = ((integer) llFrand(10000000)) * -1;
        // 2. showtime!
        state unlit;
state unlit {
    state_entry() {
    touch_end(integer num_touches) {
        if(llDetectedKey(0) == llGetOwner()) {
            llDialog(llGetOwner(), "\npick a colour", colours_names, DIALOG_CHANNEL);
        dialog_listen_id = llListen(DIALOG_CHANNEL, "", llGetOwner(), "");
    listen(integer channel, string name, key uuid, string msg) {
        state lit;
state lit {
    state_entry() {
        // 1. setup timer event
    timer() {
        state unlit;
[11:34]  Fu Barr: jimmy :)
[11:34]  Fu Barr: ari :)
[11:34]  Arielle Popstar: hey  Jimmy,  Hai  Albertr
[11:34]  Fu Barr: albertlr
[11:34]  Arielle Popstar: just  in  time
[11:34]  jimmy dayton: hi folks
[11:34]  Fu Barr: yeah - was a bit of a rush on my part... sorry.
[11:35]  albertlr Landar: Oh, just take your time Fu, we will catch up.
[11:35]  Fu Barr: I was too busy stacking prim this morning and so I didn;t prepare... so I have to rush and missed the Q&A to finish :)
[11:35]  Fu Barr: but it's all good - I got everything done in time :)
[11:36]  Fu Barr: we'll wait another few minutes and then start
[11:36]  Fu Barr: jimmy - is this your first session with us?
[11:38]  Fu Barr: right - well I don't think anybody else will turn up, so let's get started.
[11:38]  Arielle Popstar: albertr, can  you  announce the  tut  on the chat channel?
[11:38]  Arielle Popstar: it  wont  initialize  for  me
[11:39]  albertlr Landar: yea
[11:39]  Arielle Popstar: is  it  a  long  weekend  in the  USA  like  here  in  canada?
[11:39]  Mirror Amorasi is Offline
[11:39]  Arielle Popstar: lots  people  off  to their  cottages
[11:41]  Fu Barr: okay let's get going - the rest of the metaverse can catch up from the - wiki or forum :)
[11:41]  Arielle Popstar: ok
[11:41]  Fu Barr: please - take a copy of the archway, and rez it...
[11:42]  Fu Barr: if you click it post-rez, you should get a dialog, which will ask you for a colour... and if you click on one the lights will switch on and in that colour
[11:42]  Fu Barr: give it a go.
[11:43]  Fu Barr: yay! it works :)
[11:43]  albertlr Landar: We had Red White and Blue for a moment
[11:43]  Fu Barr: now - this lesson is all about pull the stuff we learned in the previous lesson together
[11:43]  Fu Barr: yes
[11:43]  Fu Barr: remember the light script we've been working on has a timer!
[11:43]  Fu Barr: so it goes off after the timer runs out :)
[11:44]  Fu Barr: let's open up the script and see what's making this thing tick
[11:44]  Fu Barr: are the perms ok?
[11:44]  Fu Barr: ie. can you open the script?
[11:44]  Arielle Popstar: working  for  me
[11:44]  Fu Barr: nice.
[11:44]  Fu Barr: always a slight moment of panic for me... I feel like the chemistry teacher... hoping his experiment wont 'blow up' :)
[11:45]  Arielle Popstar: lol
[11:45]  Fu Barr: okay - well - because of the rush to get the script done in time for class, I didn't add the v0.3 changes to the top of the script. bad fu.
[11:45]  Fu Barr: you can add them in the comment or not.
[11:45]  Arielle Popstar: so it  fu barr?
[11:46]  Fu Barr: it doesn't matter - the script works fine without :)
[11:46]  Fu Barr: hehe - yeah it's a little fubarred :)
[11:46]  Fu Barr: okay let's look at lines 20 22 ans 23
[11:46]  Fu Barr: you can see we're defining a bunch of lists
[11:47]  Fu Barr: the one in 20 has no initial values, the ones in 22 and 23 do.
[11:47]  Fu Barr: like we did in v0.2 we're going to walk the entire prim-set to find the prims we need to light up.
[11:47]  Fu Barr: but in this object we have more than one 'lamp' prim
[11:48]  Fu Barr: so instead of one variable to hold the link id of the 'lamp' we need to be able to store more than one value
[11:48]  Fu Barr: the easiest way to do that is to use a list
[11:48]  Fu Barr: we saw how those little buggers work last week.
[11:49]  Fu Barr: hey kawaii :)
[11:49]  Kawaii Unicorn: hey :D
[11:49]  Fu Barr: copy the arch and rezzit... give it a click or two and then open the script
[11:49]  Fu Barr: we're only just starting to discuss it
[11:50]  Fu Barr: so the first list we're using is 'lamps' and we don't really know what the id's of the prims are... until we loop through the link-set.
[11:50]  Fu Barr: so we dont give it values.
[11:50]  Fu Barr: the other two lists... well they are filled with date we know before hand.
[11:50]  Fu Barr: colours
[11:50]  Fu Barr: i've used the boringest colours in the universe but they serve the purpose of explaining stuff.
[11:50]  Fu Barr: i;ve used 2 lists
[11:51]  Fu Barr: one for the names
[11:51]  Fu Barr: one for the rgb colour value vectors
[11:52]  Fu Barr: the reason I didn;t merge the two lists into one - like we saw you can do in lesson 3... is that I wanted to keep this script really simple, and we'll see in a bit that iit'll be good to have the names for the colours seperate in a single list.
[11:52]  Azi Az is Online
[11:52]  Fu Barr: oh hey everyone - sorry didn't see you - you were hidden behind my script window :)
[11:53]  Fu Barr: please copy the arch, rez it, play click on it to see what it does, and then opens the script - that's if you haven't done all of this already :)
[11:53]  Fu Barr: ok - so we know understand the 3 lists in the script.
[11:53]  paela argus is Online
[11:53]  Fu Barr: and we've sort of recapped a bit about lists from last weeks lesson.
[11:53]  Fu Barr: now to this weeks lesson - functions
[11:53]  Fu Barr: on line 26
[11:54]  Fu Barr: you see there's a block of code starting, that runs to line 64
[11:54]  Fu Barr: notice that it's not inside a state
[11:54]  Fu Barr: it's not in an event handler either
[11:54]  Fu Barr: (obvious as event handler block have to be inside a state)
[11:54]  Fu Barr: it's sitting outside the states blocks
[11:55]  Fu Barr: after line 64... then the states start
[11:55]  Fu Barr: so - this block of code lines 26-64 are labeled as 'set_lamps'
[11:56]  Fu Barr: and set_lamps has a few brackets after the name...
[11:56]  Fu Barr: (setting colour_name)
[11:56]  Fu Barr: this means.... the function set_colours needs some information to work properly.
[11:56]  Fu Barr: when you try and use this 'function' - you have to tell it which colour to set...
[11:57]  Fu Barr: it's quite obvious really.
[11:57]  Fu Barr: here's this stuff in a 'normal' conversation
[11:57]  Fu Barr: hey script I want you to set the colours of my lamps
[11:57]  Fu Barr: oh, right fu, what colour do you want me to set it to?
[11:57]  Fu Barr: well, this time set it to red
[11:58]  Fu Barr: but maybe next time set it to blue
[11:58]  Fu Barr: fine, don't confuse me fu, what colour do you want me to set it NOW
[11:58]  Fu Barr: oh - make it red then
[11:58]  Fu Barr: cool. red lamps coming up
[11:58]  Fu Barr: that's basically what set_colours(string colour_name) { block of code } does for me
[11:59]  Fu Barr: so far so good?
[11:59]  albertlr Landar: yep
[11:59]  Arielle Popstar: kk
[11:59]  Fu Barr: no comments from the dazed students.. good then i'll continue :)
[11:59]  paela argus is Online
[12:00]  Fu Barr: so now forget the block of code inside the function - lets just treat it like a 'black box' and lets go to the states first
[12:00]  Fu Barr: I'm jumping to line 64... the end of the function block
[12:00]  Fu Barr: on line 67 we have an old friend - the default state.
[12:00]  Fu Barr: again - in this state nothing really happens we're just setting up the stage for the script to work.
[12:01]  Fu Barr: but this time we need to set a bunch of stuff we haven't seen before...
[12:01]  Arielle Popstar: why is  this  at the first?
[12:01]  Fu Barr: in lines 73 - 85 we loop the link set to get all the id's of the prims names 'lamp'
[12:01]  Arielle Popstar: isn't
[12:01]  Fu Barr: ari - why isn't what at the first?
[12:02]  albertlr Landar: the default state
[12:02]  Arielle Popstar: the  default  state?
[12:02]  Fu Barr: oh - it's simply a result of how the script engine works
[12:02]  Fu Barr: if you would move the function around - then the script engine will complain when you try and use the function - because it reads the script top to bottom
[12:03]  Fu Barr: the function has to be defined BEFORE you use it in code
[12:03]  Fu Barr: so it's simple to just add any functions you write before you start setting up your states and event handlers
[12:04]  Fu Barr: that way you are guaranteed that the script engine will have read your functions by the time you need to use it in some state deep down in your script
[12:04]  Arielle Popstar: ok
[12:04]  Fu Barr: does that explain it?
[12:04]  albertlr Landar: yes
[12:04]  Arielle Popstar: yes
[12:04]  Fu Barr: so just to make it 100% vlear...
[12:04]  Fu Barr: the order of 'stuff' in your script should be:
[12:05]  Fu Barr: 1. some comments at the top to explain what your script does
[12:05]  Fu Barr: 2. any variables or lists you need in your states further down
[12:05]  Fu Barr: 3. any functions you write yourself that you need in the states further down
[12:06]  Fu Barr: 4. the default state - and I would suggest you only use default for setting up your other states and script stuff.
[12:06]  Fu Barr: 5. any other states that make the magic happen
[12:06]  Fu Barr: that's really what most scripts should look like from a birds eye view
[12:06]  Arielle Popstar: ok
[12:06]  Arielle Popstar: that  helps
[12:06]  Fu Barr: comment, vars, lists, functions, default states, states
[12:07]  Fu Barr: ok - back to the script :)
[12:07]  Fu Barr: so in lines 73-85 we loop through all the prims in the link set looking for the ones called 'lamp'
[12:08]  Fu Barr: if we find one, we stick its link number into a list... called lamps
[12:08]  Fu Barr: after we run the prims.... we dump the prim id's we've found to the console... in line 87
[12:08]  Fu Barr: we don't have to, but it makes more 'educational sense' to do so :)
[12:09]  Fu Barr: so now we have the prims we're going to work with.
[12:09]  Fu Barr: notice that with this system - as long as you name your prims in the linkset... you can link and relink and add prims etc. and the script wont break
[12:10]  Fu Barr: the script doesn't care about the link id's - it just cares about the names you give the prims - if you do that, the script will always figure out which prims to use
[12:10]  Fu Barr: so you can remove or add 'amp' prims to your hearts content
[12:10]  Fu Barr: ok.
[12:10]  Fu Barr: on line 90
[12:10]  Fu Barr: we generate a random number
[12:11]  Fu Barr: we need this number for our dialog to work - we'll see how/why in a few moents
[12:11]  Fu Barr: but for now just see that we generate a LARGE number
[12:11]  Fu Barr: and then multiply it with -1
[12:12]  Fu Barr: to make the number NEGATIVE
[12:12]  Fu Barr: again we'll see in a minute why that is.
[12:12]  Fu Barr: and then in line 93 we get the show on the rod.
[12:12]  Fu Barr: any questions so far?
[12:12]  albertlr Landar: no
[12:12]  Fu Barr: nope great
[12:12]  Fu Barr: so on to the next state...
[12:12]  Fu Barr: lit
[12:13]  Fu Barr: on line 102 - the magic happens
[12:13]  Fu Barr: this is the core of today's lesson
[12:13]  Fu Barr: when I move into the the unlit state...
[12:13]  Fu Barr: I simple call the function I defined before and ask the script to set the lamps to 'none'
[12:14]  Fu Barr: at this point the script engine jump to line 26
[12:14]  Fu Barr: and executes the code block that is written there.
[12:14]  Fu Barr: then it comes back to line 103
[12:14]  Fu Barr: once the code in lines 26-94 is run
[12:15]  Fu Barr: on line 103 nothing much happens - it just closes the block of the state_entry event handler.
[12:15]  Fu Barr: so this is the core of todays lesson
[12:15]  Fu Barr: functions allow you to repeat code in many places in your script
[12:15]  Fu Barr: it allows you to write shorter code.
[12:15]  Fu Barr: and shorter code means less mistakes
[12:16]  albertlr Landar: basically the functions allow a shorter version of the code, which can be used over and over in different places.
[12:16]  Fu Barr: and also if your function is only written once but called from several places in the script... if you change the code in the function - it changes everywhere you 'call' it. so you only have to make changes to your code once and it will work the same everywhere you use it
[12:17]  Fu Barr: yes -exactly albertlr
[12:18]  Fu Barr: generally if you find that you're writing the same code over and over in your script - it's a sign you should be putting that code into a function
[12:18]  Fu Barr: and the clever part of functions is that you can make them do various things because you can send them information
[12:18]  albertlr Landar: and those are the purposes of the OSSL functions?
[12:18]  Fu Barr: now we're just sending in the colour name
[12:18]  Fu Barr: not really- this is just me explaining the general idea of 'functions'
[12:19]  Fu Barr: the OSSL functions are things that the opensim peeps felt were missing in the original LSL language...
[12:19]  Fu Barr: and some things that only make sense in opensim - like NPC's
[12:20]  Fu Barr: but the general idea is - oh look I'm doing this stuff more than once in my code - cool, let's turn this into a function
[12:20]  Fu Barr: so far so good? any questions?
[12:20]  albertlr Landar: yea
[12:20]  albertlr Landar: no questions
[12:20]  Fu Barr: just to be 'complete' the info you send into a function are called 'parameters'
[12:21]  Fu Barr: the whole line of function Name(parameter1, parameter2, parameter3) is called the function 'signature'
[12:21]  Arielle Popstar: what activates  the  dialog  box and  sets  the  names  of  the buttons?
[12:21]  Fu Barr: we're getting to that right now Ari :)
[12:21]  Arielle Popstar: kk
[12:22]  Fu Barr: now that we've explained all about functions - lets finish up and see how the rest of the script works..
[12:22]  Fu Barr: ari - look at line 109
[12:22]  Fu Barr: the LSL function we need for the dialog to pop-up is called 'llDialog'
[12:22]  Arielle Popstar: ah  kk
[12:22]  Fu Barr: that function takes 4 parameters
[12:23]  Fu Barr: llDialog(uuid_of_avatar, message to show on dialog, a list of buttons, the channel to return the choice of button to script on)
[12:23]  Fu Barr: if you hover over the llDialog in the script editor - you'll get a short help note with the relevant parameters.
[12:24]  Fu Barr: this works for ANY built-in LSL or OSSL function
[12:24]  Fu Barr: obviously the editor know nothing about the functions your write yourself - so it doesn't do the pop-up help thing
[12:25]  Fu Barr: now - here's the catch
[12:25]  Fu Barr: there are MANY LSL and OSSL functions
[12:25]  Fu Barr: and they all need a bunch of parameters to work properly
[12:25]  Fu Barr: and that is why when you write scripts... you almost always have the LSL or OSSL wiki pages open in a web browser
[12:26]  Fu Barr: you need to look up these parameters all the time
[12:26]  Fu Barr: what they do, what you need to provide etc. etc.
[12:26]  Fu Barr: at some point you'll remember the more frequently used ones - but you'll still be coding like you're watching a tennis match
[12:27]  Fu Barr: look at your code, look at the wiki, look at your code, look at the wiki, look at your code, look at the wiki
[12:27]  Fu Barr: till you make a mistake and the 'ball' goes out and you have to debug
[12:27]  Fu Barr: round and round this dance goes till you complete the bug-free script
[12:28]  Fu Barr: okay - lets wrap up the llDialog stuff and the rest of the script is trivial to read and understand in your own time
[12:28]  Fu Barr: llDialog (if you read the wiki page) behaves like this
[12:28]  Fu Barr: it shows the dialog, then waits for a button press
[12:28]  Fu Barr: if you press any button except 'ignore'
[12:29]  Fu Barr: the label of the button gets 'said' on the channel you tell it to chat... in our case we generated a channel number and stuck that number into DIALOG_CHANNEL :)
[12:29]  Fu Barr: so when you press 'red'
[12:29]  Fu Barr: the dialog says the word 'red' on channel -3235663246
[12:30]  Fu Barr: depending on what the random number is that the script generated in the default state
[12:30]  Fu Barr: now... look at 115
[12:30]  Fu Barr: there we have the listen event handler
[12:30]  Fu Barr: it sits and listens
[12:31]  Fu Barr: and when something is heard it does the code in the code block... in our case it call the set_lamps function
[12:31]  Fu Barr: and if you look carefully on line 117
[12:32]  Fu Barr: the parameter it sends into the set_lamps function is.... the 'string' msg which is what was said on the channel... which happens to be the name if the colour...
[12:32]  Fu Barr: and so on line 117 - the script hops to line 26
[12:32]  Fu Barr: feeds 'red' into the function.. does the code there till line 96 and jumps back to 118
[12:33]  Fu Barr: the listen event is setup on line 112 - and that's where you tell the script to listen on DIALOG_CHANNEL :)
[12:33]  Fu Barr: anyhow - that's really the whole thing.
[12:33]  Fu Barr: a few lists
[12:34]  Fu Barr: one function that changes the colours and glow parameters of a few prims in a link-set
[12:34]  Fu Barr: and a Dialog with a listen event.
[12:34]  Fu Barr: dassit.
[12:34]  Fu Barr: the rest is just a bit of boilerplate to grease the wheels.
[12:35]  Arielle Popstar: kk  cool
[12:35]  Fu Barr: I can read more of the script - with you guys, but I figure it's best if you pull it apart yourself and try to modify it
[12:35]  Fu Barr: breaking stuff is very good way to learn :)
[12:35]  Arielle Popstar: :)
[12:36]  albertlr Landar: as long as you keep the working one as back up
[12:36]  Fu Barr: oh - there's one more 'trick' I use in the et_lamps function///
[12:36]  Fu Barr: maybe I should say a few words..
[12:36]  Fu Barr: if you look in lines 31 - 45
[12:36]  Arielle Popstar: helps  to be  able  to  recognize  what different  parts  of  a  script  are
[12:37]  Fu Barr: what I do there is setup the values for the rgb and the glow of the prim...
[12:37]  Fu Barr: I collect those values first
[12:37]  Fu Barr: then once I have the right values then I loop through the links in the lamps list.
[12:37]  Fu Barr: the reason is that it makes the code much cleaner.
[12:38]  Fu Barr: it's like cooking with a good menu in place.
[12:38]  Fu Barr: anyhow - that's it. end of.
[12:38]  albertlr Landar: ok
[12:38]  Fu Barr: I hope these 4 sessinos have been useful
[12:38]  Arielle Popstar: they  have  for   me
[12:38]  Fu Barr: you should be able to start writing and/or modifying scripts now with out much 'fear'
[12:39]  albertlr Landar: well I am looking into how to best add line numbers to the scripts already in the wiki, as they are important for people to follow you.
[12:39]  Fu Barr: and you'll also start to see that there's a LOT of very bad code out there.
[12:39]  Fu Barr: so my last tip is... when you get a new script... look for the stuff that makes it tick... and then throw it away, and write your own version.
[12:39]  albertlr Landar: I should have this script and the chat in the wiki by Friday at the latest.
[12:40]  Fu Barr: and also - scripting is something that NEEDS lots and lots of practice.
[12:40]  Fu Barr: that's it for the basics.
[12:40]  Fu Barr: me done.
[12:40]  Fu Barr: fin
[12:40]  Fu Barr: end
[12:40]  albertlr Landar: like writing a novel, if you don't get all the plot twists right it does not work out right.
[12:41]  Arielle Popstar: its  a wrap
[12:41]  Fu Barr: that's all folks!
[12:41]  albertlr Landar: Thanks Fu, you are appreciated.
[12:41]  Fu Barr: dont forget to clear up your prim when you leav
[12:41]  Fu Barr: e
[12:41]  Fu Barr: hehe - the hidden avvys' have all left
[12:41]  Fu Barr: I must have bored them to tears
[12:42]  Fu Barr: well it's all on the wiki and forum now - I would have to teach this ever again.
[12:42]  albertlr Landar: not at all they went to contemplate the wisdom you have shared oh sage.
[12:42]  Fu Barr: lol - albertlr - i;m not so naive to think that. there's shopping to do and dances to be at with bouncy boobies LOL!
[12:43]  albertlr Landar: ok
[12:43]  Cataplexia Numbers is Offline
[12:43]  Fu Barr: anyhow - I did my bit for King and Country
[12:43]  albertlr Landar: well thanks again for all this, it does give us more to sure in the wiki.
[12:43]  Arielle Popstar: lots  of  people  as  a  holiday  weekend  and  last  before  school  starts
[12:44]  Fu Barr: maybe next time we'll do prim building or something like that.
[12:44]  Arielle Popstar: yes,  thank  you  Fu
[12:44]  Arielle Popstar: good  idea
[12:44]  albertlr Landar: and that would be a big help to lots of people too.
[12:44]  Fu Barr: thanks ari for putting this stuff up on the forum - and albertlr - thanks too
[12:44]  Arielle Popstar: prims  becoming  a  lost  art with  all the  focus  on mesh
[12:45]  albertlr Landar: I prefer prims myself.
[12:45]  Fu Barr: yeah - I think building is becoming less of the 'thing' in the virtual
[12:45]  Fu Barr: its about finding the mesh you like and rezzing it
[12:45]  Arielle Popstar: yes
[12:45]  albertlr Landar: when it does rez
[12:45]  Fu Barr:  I  be surprisedto find more than a handful of people who actually build stuff anymore
[12:46]  Arielle Popstar: and then be  frustrated  when  you cant   modify  it
[12:46]  Cataplexia Numbers is Online
[12:46]  Fu Barr: in-world I mean
[12:46]  albertlr Landar: Bye all.
[12:46]  Arielle Popstar: tc  albertr
[12:46]  Fu Barr: ciao