Building A Second Life Checkers Game #5

As I mentioned in the previous post, finding the size of a non-root prim from a Second Life Script in the root prim is a pain.

What really makes this a puzzler is that setting the size is pretty darn simple. So I'll look at that first.

I used this same call in the last post to set the position

llSetLinkPrimitiveParams(pieceLinkNum,[PRIM_POSITION, vectPos]);

It is the same call you would use to set the size.

llSetLinkPrimitiveParams(pieceLinkNum,[PRIM_SIZE, vectSize]);

So what's the big problem? Well, there is no llGetLinkPrimitiveParams. What!?! But what about this code to get the location using the object key.

key pieceKey = llGetLinkKey(pieceLinkNum);
list d = llGetObjectDetails(pieceKey,[OBJECT_POS]);
vector vPos = llList2Vector(d,0);

That seems simple enough, except when you look closer at llGetObjectDetails it is not llGetPrimitiveParams. Object details are only a few parameters like name, description and size. Then if you dig for an hour like I did, you find that there is no 'easy' way to get PrimitiveParams given a link number or an object key. You will find it on a Wish List of functions and can just give up until someone finally decides to implement this function that seems so useful, but seems to have been overlooked.

Or you could be like me and figure out a way to get it done, knowing the mantra "There is always a way. There is always a way. There is always a way." I can't seem to find it now, but there was some obscure reference on some wiki page that said it didn't exist and you have to use link messages. So here goes.

Link messages are a way to send messages from one prim to another in a link set (link sets are groups of prims, but group would have been too confusing the Linden folks say). Even though it is frowned upon to have scripts in all the linked objects, this is the only way to get this done.

When I traverse the list of pieces I look for the name of my piece to get the linknum of that piece.

integer i=2;
integer count = llGetNumberOfPrims();
for (;i>count;i++)
{
  string stName = llGetLinkName();
  if (stName == "thepiece")
  {
    // send the link message
    pieceLinkNum = i;
    llMessageLinked(pieceLinkNum,PRIM_SIZE,"43",NULL_KEY);
  }
}

I'm sending PRIM_SIZE as the message number just because I don't have any other messages. In good practice I could probably send a number that is associated with some hair brain scheme I came up with on the fly, but since there is only one message to this prim, anything will do. Normally I would chose 42 since that is the most important number in the universe. Which seems strange in that I did use 43 for the message number that will be used when returning the size to this root prim from the linked prim.

Inside the linked prim, I need to setup a way to receive that message. It is the only thing that script does, which is a good thing. Avoid scripts in linked prims if at all possible.

default
{
    link_message(integer sender_num, integer num, string ret_num, key id)
    {
        if (num==PRIM_SIZE)
        {
            list re_list = llGetPrimitiveParams([PRIM_SIZE]);
            //llOwnerSay("re_list = "+(string)re_list);
            llMessageLinked(LINK_ROOT,(integer)ret_num, re_list, NULL_KEY);
        }
    }    

}

This gets the size using llGetPrimitiveParams([PRIM_SIZE}) which returns the correct value since this is in the prim we want the size from. I then return this size to the LINK_ROOT using the message number that was passed in the link message.

Back to the root prim, here is the code to receive that message.

link_message(integer sender_num, integer num, string list_argument, key id)
    {
        if ((sender_num==pieceLinkNum) && (num==43))
        {
            //llOwnerSay(" list_arg = "+(string) list_argument);
            pieceSize = (vector) list_argument;
            //llOwnerSay("received pieceSize="+(string)pieceSize);
        }
    }    

I save that size into the global variable pieceSize which I can then use in other calculates.

Note, I went through this whole exercise thinking I needed the size of the piece to calculate it's location on the board because I would have to center the piece somewhere. After all that, and a ton of failed attempts I remembered that the origin is automatically the center and I didn't need a single line of this code. Gotta love programming for the amount of time I've wasted in my life. I'm sure I'll use this elsewhere though.

Building A Second Life Checkers Game #4

I was making good progress on the checkers game, but something was nagging at me in the design and I decided to take a step back and see if there might be a better way. In the current design, I've been saving the initial placement of all the pieces (as a list of vectors) on initialization and using those locations when people move or choose the location to move a piece. I had been avoiding calculating the locations programatically for no other reason than it seemed like it might take more thought (ie. lazy). But then there was the nag in my head that said it needed to be investigated, so I took the board apart and made a new one just to test how difficult it would be to programatically calculate the locations on the board.

Here is a screenshot of my mockup environment.

The positions would be numbered 0-63. The starting location would be 0. Touch the green button and the piece would move to the next position.

The first problem is to find the size of the board. Since it is the root object it's pretty easy to find. To note, if it's not the root prim you are screwed and it is very difficult, and I'll talk about that in the next post. The size (PRIM_SIZE) is the actual size of the object in meters. When calculating the location on that prim with local coordinates, the origin is at the center of the prim.

list params = llGetPrimitiveParams([PRIM_SIZE]);
vector sz = llList2Vector(params,0);

Next is to calculate the x and y row and column. This is also very simple given there are 8 rows and 8 columns.

integer px = curPos / 8;
integer py = curPos % 8;

I then calculate the size of each square and save it.

float sqr_x_size = sz.x / 8;
float sqr_y_size = sz.y / 8;

Once you have all that it is fairly straight forward to calculate the location of that square, but look at all the comments and see how many tests I went through to get it right. Tons of experimentation here.

//llOwnerSay(" sqr_x_size="+(string)sqr_x_size+" sqr_y_size="+(string)sqr_y_size);
vector p = < (sqr_x_size * px) - (sz.x/2) + (sqr_x_size/2),
             (sqr_y_size * py) - (sz.y/2) + (sqr_y_size/2),
             0.051 >;

//vector p = < (sqr_x_size * px) - (sz.x/2),
//             (sqr_y_size * py) - (sz.y/2),
//              0.1 >;                                    // the position without centering on the square
//vector p = < sz.x/2, sz.y/2, 0.1 >;          // the origin
//vector p = < -sz.x/2, -sz.y/2, 0.1 >;        // the negative origin - this didn't work
//vector p = <0,0,0.1>;                            // the 0,0 location which is the center of the board
//vector p = <(sqr_x_size/2),(sqr_y_size/2),0.1>; // just a futile experiement to offset from the origin some amount
//llOwnerSay(" new pos = "+(string)p);     // the debug message seen over and over and over again

Given all that, the actual calculation that I used can be summed up like this.
For x: The location given the x location minus the offset because the origin is the center + the offset of half a square to center on the square.
For y: Same as x
For z: Just a number which I twiddled to get right.

The last step is to set the actual location. This is pretty simple given that you know the link num for the piece you want to move. This number was retrieved on initialization. After that, change curPos and wait for the next touch.

llSetLinkPrimitiveParams(pieceLinkNum,[PRIM_POSITION,p]);
curPos++;

And yes, this was more work, but as I expected it will be a lot more efficient and easier to work with in the long run.

Building a SecondLife checkers game #3

Serious design problems.

My checkers game is now receiving a:
Script run-time error
Stack-Heap Collision

I know what the problems are and I know how to fix it, but it does show how flexible software development needs to be. I knew going in that memory constraints on the scripts were going to be tight, I just didn't figure I would hit them this quick. Here is the latest screen shot.

The good news is that I know what the problem is and I may not need to change the design too much.

The green triangles are not visible during game play except to choose the location where you can move a piece. The mechanic is to touch the piece you want to move, then the green triangles appear in locations that are open, then you click on the triangle. I've got all the movement and placement of the triangles working.

The problem occurred when I created enough extra triangles for the number of moves that might be available. For the pieces I'm saving the original location vectors (three floats) in a list. Including the ones in the center which will become the king pieces. Then removing the kings from the board (you can see the storage box in the back which will be moved under the table at the end. These vectors are big and I was also saving the triangles just for testing and that is where I hit the problem. I can really just keep them off the table at all times and don't need their initial locations. So, even though I hit what seems like a big snag, all is not lost yet... And even if it were, there is always a work around. Always.

Building A Second Life Checkers Game #2

I'm making progress on the checkers game and thought I would talk about some of the data structures.

The available LSL data structures are quite limited, but enough to make scripts that do anything.

The biggest thing you learn early on is that there are no arrays. At least not like in other languages. What they do have are lists which are basically arrays, but you have to use special functions to manage the arrays.

As an example, I know my board has 32 spaces so I have a list that contains the piece number at any given space. You first have to allocate space for the 32 spaces.

list board;

InitializeBoard()
{
  integer i=0;
  for(;i<32;i++)
  {
    llListInsertList(board, [-1], 0);  // -1 means no piece is there
  }
}

As I traverse through the linked pieces (see previous entry), I insert them into the board at their location which is defined with a little CSV in their title "r,1,1". The first letter is the color, the second is the piece number and the third is the location which are the same. I may have over designed the piece number and location...

Once you know the piece number you can add it to the data structure (list) holding the locations on the board.

board = llListReplaceList(board,[piece_num],piece_location,piece_location);

One thing to note, ReplaceList creates a whole new list and returns it. You WILL at some point screw this up and not have the board = in there and wonder why your list update didn't occur. It is just part of the learning curve. I'm sure I'll do it again and again and waste more hours. I think the compiler should warn you of this since it seems so necessary and such a common mistake.

When you want to access an element in the list you do so knowing the type that you previously stored in the list. In this case it was an integer and if I want to know what was at location 3, I would do this.

integer pieceAtLocation = llList2Integer(board,3);

For other types stored in lists, there are other functions, llList2String, llList2Vector, llList2Key, etc...

Distilling a Second Life harassment incident

When building my checkers game I've had a number of people approach and touch the board and at least two attempts to disrupt and divert my attention. On both I asked them nicely to stop and reported the incident as harassment when they didn't. I sent an IM to both people. The second person (who had built a lot of large cubes over the area I was working and made me move, he also used a lot of expletives) became irate and came back upset when I told him I had reported the harassment. I didn't responded to any of the verbal attacks and I was finally able to distill the incident by saying something like this.

Me: Hey, how about we work together on something together instead being disruptive. I find that life is a lot more fun when we help each other and work together.
Me: I think it would be interesting to work on a project with you. I have a lot of programming experience and help on the scripting side of a build.
Mr. Disruptive: You mean a truce?

(I never knew I was at war)

Me: Yeah, sure.
Mr. Disruptive: Okay, cool.

He had left the area and then asked me for a teleport. He never really talked to me again, but he hung out in the area tweaking a spheroid and soon added me as a friend. So as I've found in life and now in virtual life, bad situations can usually be distilled by an offer to work together even when one person is bent on being disruptive. The charity work I do is the most rewarding thing that I have ever done and I'm always looking for ways to continue those efforts. It seems there is even room for this type of work in the virtual world!

I wrote this up a few days ago and he actually came back around to show me some new emotes he had received from a friend. I think he's just a kid, but its much better than the initial interactions.

Building a Second Life Checkers Game

I (SL: Wood Wheels) have been working on a checkers game in Second Life. This is just a learning experience and a chance to really dig into a new language. I've found that the best way to learn a new language is to build something and keep increasing the complexity. I've built a bunch of houses, doors, lamps and a soccer ball, but this is definitely the next step in the evolution of my understanding.

There are a bunch of lessons learned so far and I thought this would be a good opportunity to pass some of those on beyond a couple of updates to the lslwiki and slwiki.

The first lesson was where I started out giving each game piece it's own script and sending messages back to a larger script attached to the board. This was using Link Messages (llMessageLinked). It was good that I figured out early that this was the wrong way after reading the section on Script Effeciency. #1 in efficient design: If you need to have a bunch of buttons, don't put a script in each prim, use llDetectedLink number.

I now have only one script in the board. By default, each linked prim has a link number and you can traverse the list of linked prims using something like this:

integer count = llGetNumberOfPrims();
integer i = 2;
for (;i<=count;++i)
{
  string stName = llGetLinkName(i);
  list namelist = llCSV2List(stName);
  string stType = llLink2String(0);
  string stPieceNum = llLink2String(1);
  if ((stType=="r") || (stType=="b"))
  {
    llOwnerSay("have a "+stType+" piece numbered "+(string)stPieceNum);   

    // I also save the link number, color and piece number 
    // in a list which I'll show later
  }
}

I gave each piece on the board an object name of "r,1" or "r,2" which allows me to identify which piece is touched during the move. I then convert this name to a list (llCSV2List()) to separate out the color and piece number. You might note that i started with 2. The board, which is the root prim (the one selected last when linking), is number 1 and I don't include it in the lookup. I don't have the move mechanic completed, but the early design of it is working and I'm refining the movement code now.

There is probably a lot more to talk about and lists are a big part of the design. I'll try and write more on that tomorrow.

Does Anyone Like GridBagLayout??

Does anyone like GridBagLayout? I know I've fought it at times and this animated blog entry is a hillarious parody. Although I don't think parody is the right word since it does seem to mimic reality.

Doom Slayer III

One of the student games in the contest I ran two night's ago did a two minute trailer for his game. It was actually really fun to watch and I thought I would link to it here since he just uploaded it. Most of the content from this video was in game capture. It is a real game that is fully playable, created by a sophmore at Chapman University in about 6-7 weeks. A huge piece of work for that short of time. He is going to be an amazing programmer.

Doom Slayer III
http://www.youtube.com/watch?v=PN5E3E_nIhA

I've already posted it, but the final results of the contest are here.
http://www.gamedev360.com/contest07/

Game Development Contest Results

Last night's contest for my class was amazing.

http://www.gamedev360.com/contest07

The RailGunner game is an amazing piece of work built in about six weeks. Jess and Noah really outdid themselves. Even the second (T-Orc) and third place (Doom Slayer III) games were very nicely done. Rail Gunner and T-Orc are fully playable. Doom Slayer III while not completely done had a ton of code to it. He even did a trailer that was hillarious and everyone enjoyed. I'm hoping he uploads the trailer for others to see.

All in all I think everyone enjoyed themselves and I think a number of the students will get jobs. There was enough time at the end for the industry folks to mingle with the students and I'm sure a number of them will get calls.

One of the things that became apparent and I had sort of forgotten about it was the fact that half of my class were seniors and half were freshman. I went really fast in the first few classes knowing the freshmen were out of their experience level and hoping they would drop. A number of them did, but a few of them stuck with it and while they didn't have winning games they did have some impressive pieces of work. Although I should mention that Jess (one of the winners) is only a sophmore. Brilliant.

One of the crowd favorites was a freshman game called Beer Sweeper. It was fun to watch as Luis kept raching around the virtual recreation of an actual dorm room (it was very close, I once lived in that same dorm) the keys started to change and it became very hard for him to control. It got some good laughs.

The fourth place game Ork Fight had a ton of AI code and Chris got the orcs to fight on teams with the other players. It was very fun to watch. He had some funny stories about problems while he was working on the AI. Some of the problems sounded almost human.

The fifth place game was a huge endeavor. Given a few more weeks I think Vinnie would have taken first place. He's going to be the Peter Jackson type some day. Double majoring in Film and Philosophy and a minor in computer science he made some major engine modifications and is well on his way to a significant creation.

All in all it was a great semester. I worked way too hard at it and didn't make much money, but I love doing it and I'm looking forward to at least taking a semester off. I'll decided later in the year if I'll do it again.

Tonight's Contest

Tonight is the night I'm hosting a bunch of local game industry folks to view the student projects and presentations. The best game get's a $100 gift card, but the students have done most of the work with the opportunity to get in front of a bunch of folks from industry. It's an experiment, but right now the wave looks a lot bigger than I ever expected.

This is how judging will be weighted. It doesn't have anything to do with their grade on the project, just who 'wins' best game.

Completeness: (25 %)
Replay/fun factor (20 %)
Uniqueness (15 %)
Story (10 %)
Graphics (10 %)
Simple graphics that are used in a unique way will also receive high scores here.
Audio: (10 %)
Student Choice: (10%) (max 90 points = 18 students x 5 points each)

I've tried to break completness out into the following sub items: Splash screen, main menu, Scoring, Game has a story, Game controls/play, multiple levels, game ends/menu cycle/quit, high score system.

I have this obscene spreadsheet created which will automatically calculate the winner based on judges input. Once I have the number (1-100) from the judges for each game and category I simply imput them and come up with a winner. I did this last year, but I put the numbers in as I went. I just hope it doesn't take forever to enter the data, but things have a way of working themselves out. I'll report again tomorrow with the winners.

Just as I finish writing this I may dump the spreadsheet and just ask for the judges first, second and third choices for the winner. Hmmm.

Game development class - huge finale

If you've been following my blog you know I've been teaching a game development class. The student's have been working on their own creations for almost half the semester and here is a (two week old) preview of the results.

http://www.gamedev360.com/contest07/preview.html

I have about 10 people from five of six of the biggest game companies in the area coming to judge the final presentations. I offered the student with the best game a $100 EB giftcard. Last year they were focused on the gift card, this year I'm sure they are focused on the job so putting them together with people who are looking for talent seems like a win win for everyone. All sides are excited.

I went into the lab on Saturday to help students with last minute problems and I have to say this is one of the best group of students I have ever had. The quality of the work is phenominal. The screenshots on the contest preview are almost three weeks old and the games since then are looking very very polished. A couple of them are going to be standouts.

There was the funniest quote the other day in one of the extra lab sessions. About halfway through the class I stopped assigning homework and allowing the student's to work on their own projects. One of the student's said to me, "Man, when you stopped assigning homework this class got a lot harder!". That has to be one of my all time favorite teaching quotes. The pressure of the final presentation in front of industry seems to have really worked.

I'll try and post results of the contest on Wednesday. I've been spending every minute of my free time on this contest. What am I going to do with all that extra free time?

Torque Development Process

I find that I like the workflow in developing games in Torque. As long as you are just using the base engine without any c++ changes to the engine itself it is as simple as keeping the engine exe file in the same directory tree as your script code and just running the engine for each test pass. The engine will automatically compile your scripts to bytecode if the source has changes since the last compile. Once you are ready to release you simply copy everything to a release directory and remove all the source.

I'm betting you could do 99% of your game this way unless you really chose to do something that was out of scope for the actual engine. In that case you would either need to choose a different engine, or make a lot of mods to the C++. In any case, I do like the workflow in developing for Torque. Even those mods are pretty simple.

It is a little strange since I remember at first thinking it was crazy that I had to re-run the engine after every change. It just seemed to go against the grain of what I'm used to, but now that I think back on it, I do tend to re-run everything no matter what platform I'm developing for. Maybe it was just that I wasn't used to the engine actually doing the compile and expected a traditional environment of having to compile before running? In any case, it is a good system.

Torque Introductory Tutorial

I missed class last week because I've been sick. I'm feeling better now and I've been working on this week's lecture. I found that when I got stuck on one of the examples I was building I immediately went back to the introductory tutorial that comes with the engine. It's file name is GettingStarted.pdf and it is in the examples directory. This really is a great place to start and I find myself returning to it for quick refreshers. I found one online here, but I don't think it is supposed to be there.

Anyway, if you are going to use Torque, keep this tutorial handy.

The student's marketing materials are due tonight. Just a simple screen shot and 1 page of html. Just enough for me to get something out to the judges so they can get a preview of the games they will be judging.

Apples To Apples - Fun Party Game

It's Thursday, time for some fun. When I worked at a game company we used to have Thursday game night every week where we would turn off the computers at 5 and head to the conference room for some old fashioned gaming. We were a small group (about 8) and had two exceptional game designers who also had large collections of board games. I'm going to take a quick diversion from game development each Thursday and talk about some of my favorites.

One of our favorites was a party game called Apples To Apples. It had just come out and is now available everywhere, but I'm sure not everyone has heard about it now? Very very simple to play and a lot of fun and laughes for a group of 4-10.

The basics, one person (let's say my friend Hank) plays a random green card face up. It says "annoying". Everyone else has to play a red card (face down) from their hand that they think Hank will choose for the word 'annoying'. You have a hand of 8 preprinted cards and the choice of card you play would probably be different depending on which person in the group is choosing. The cards in my hand might have things like. "Marilyn Monroe", "My Social Life", "Hockey", "Celine Dion", "Tornados", and "Strawberry Pie". After everyone has played a red card from their hand face down, Hank might end up with cards like: "Craying babies", "The NRA", "My Haircut", "A bar room brawl", and "Celine Dion". (you can see which card I chose. feel free to leave an angry comment. Even though I think the NRA is annoying that person doesn't know Hank is actually a gun lover). Hank turns them up one at a time and reads them out loud. After, he picks the one he think matches "annoying" the best. Now, if Hank thinks the way I think he should think, he'll choose "Celine Dion". If he does, I first give a Homer Simpson Whoooo Hooo, then I get to keep the green card. First one to some number of green cards (typically 4 or 5) wins. See, simple.

Many of the card combinations are hillarious and you'll have a great time with any group. A very fun game and did help build cohesion within our team.

Is Torque the best game engine for my project?

I was asked in an e-mail if Torque would be the best engine for a specific project. I wasn't given much information on the project, but this is my opinion on the matter.

For commercial games Unreal is the king and owns about 90% of the market. It is in the $100-200k range to license so it is out of reach for anyone that isn't very very serious. I'm not completely sure on the pricing because it's something that isn't advertised. They price it on a case by case basis and we tried to get a license for Chapman University and that was the range we were given.

The next most popular engine for commercial games is a tie between Quake and Half Life. Both have similar licensing expenses, but rumor has it that the Half Life engine is very hard to understand. I don't know first hand. Of the three I think Unreal is probably the easiest to learn having spent some time with it. Torque has a very strong following, but is mostly seen as a hobbyist engine. That doesn't make it bad by any means, but that is the view. It is well supported and while there is a steep learning curve, it isn't any steeper than the other engines out there. There are a number of commercial games available on it and the company just released a next gen version of the renderer so it is still growing and doing well.

The next thing to keep in mind is the game itself and if the engine supports the type of interface you are designing. Each engine has different specialities and one engine may be best for one design and wrong for another. Torque is best at FPS or third person multiplayer games. There is also a 2D version of the engine which I would also highly recommend.

Torque Game Engine (3D) does not have a good physics engine. I think the others are better, but there are a lot of threads out there on the Torque forums that talk about integrating other physics libraries. The 2D version has a great physics library.

Game Development or Game Playing

Not all game development is without it's fun side. One of the main reasons I'm into game development as a hobby is that I've loved to play games since I was a kid. It all started with that pong game my dad bought when I was about 9. The console wars have been going on ever since.

My current console is a ps2 which I have not played in a while. I was playing a lot of game boy until I gave it away to an orphanage in Africa when we were on a mission trip. I do miss it, but those kids really loved it a lot more that I ever would.

My current game is World Of Warcraft (Character Ironwood, Realm: Duskwood) One of the most addictive games I have played. Probably the most addictive for me since I got to 67% complete on GTA III, Vice City and San Andreas. Anyone who has played those knows 67% complete is too much fun time and not a lot of TV. I'm not sure where I stand in WoW, but I'm sure it's only in the 20% range at level 31. Lately I've slowed my progress and have been working on my Leather Making and Cooking skills. The game is very open ended and has a lot of ways to play. My only complaint is that I'm a bit bored with the same monsters over and over and over with a slightly different skin or model, but it's still a lot of fun.

With 8 million subscribers and still growing don't take my word for it, this is a fun game. Don't start if you don't have some time to waste. I started in January and three months later I'm finally starting to get a little bored with it. I'll probably drop my subscription in June if my usual game life cycle runs it's couse. A very fun game.

Torque - Torsion IDE or Eclipse

I've been trying the Torsion IDE for Torque Game Engine this week. Before I was using TextPad or CodeWright and just managing the projects by hand. It wasn't a big deal before, but I did have to find the error lines by hand.

The biggest difference is that the error output has a clickable interface and keeping the errors red makes it much easier to find the errors in the log. My only gripe so far is that the log window is not searchable which is annoying, but it has really sped up my workflow in so many other ways that I think I'll probably buy it when the 20 day trial is over.

I've seen some mention a that there is an eclipse plugin for Torque. I've been a long time user of NetBeans. I typically find an environment that I like and stick with it until it's either irrelevant or something very compelling gets me to switch. I'm doubting the Eclipse plugin is as closely tied to the Torque engine (it has a built-in debugger I have not yet tried) as the Torsion IDE and wonder if the error logs are hot linked to the source lines?

Has anyone tried the Torque plugin for Eclipse and have any insight? It might save me some time and frustration of learning yet another IDE although that will probably start some sort of flame war with people pitching one IDE against another. My view is that the tool that works for you/me is the best tool and it's just not worth arguing over.

Torque Script - datablocks - very confusing

It took me quite a while to really understand datablocks in Torque. All the books say exactly the same thing.

Of all the features in TorqueScript, Datablocks are probably the most confusing. To make things worse, they are central to the creation of most objects, which means you need to understand them relatively early.

I think all the books plagiarized this from the official documentation on datablocks.

Datablocks are just shared objects that contain static data that doesn't change from one object to the next. So the engine can send it once over the network and reference it by id from then on. I get this and I think every explanation made this perfectly clear. The problem is that all the callbacks from the engine into the script code comes through these datablocks. For instance:

datablock StaticShapeData(SomethingData)
    {
    // Basic Item properties
    shapeFile = "./mymodel.dts";
    };
function SomethingData::onCollision(%this, %obj, %col)
    {
    // your code here
    }

This really confused me and I was trying to create my own object types to no avail. The code above creates a type SomethingData which will show the 3d model contained in the file mymodel.dts. This is fine, but the call to onCollision is done on the datablock object (SomethingData) versus the object itself which in this case ends up being a StaticShape. Since the datablock is static and shared across all instances I couldn't figure out why or how you kept data in individual objects.

I finally had an epiphany when I noted that %obj is always passed into the callbacks and is the actual object instance. Individual changes and values can be made in this object. Seems simple enough now, but this killed some brain cells for me.

So I placed this comment in one of my pieces of sample code for class.

function SomethingData::onCollision(%this, %obj, %col)
{
  /*   * MANTRA - REPEAT OVER AND OVER UNTIL DATABLOCK UNDERSTANDING SETS IN
   * 1. %this is the datablock   * 2. %obj is the object instance
   *
   * of much less importance
   * 3. %col is the object colliding

Here is the lecture where I tried to explaing this. I think the notes are still a little jumpy, but the in person version seemed to clear things up for students. Your fuel economy may vary.

Torque Script - Behind The Scenes

Torque script is the scripting language behind all of the Torque Engines is a simple, but robust scripting language that is very easy to learn. All game engines include a scripting engine and Torque is no different. For non-game developers, the idea of a scripting language may seem like a negative, but there aren't any commercial games that don't use a scripting language.

Most non-game developers may at first think that this means the source to parts of your game are shipped with the game, but this is not the case. Torque script is compiled into a bytecode format and saved to a separate file (.dso extension). Everytime the game engine runs it does a date comparison between the source (.cs) and the compiled files. If the source is newer, it re-creates the bytecode file. If the source file does not exist, it simply uses the bytecode file. You simply ship your final version without the source files.

This is transparent and very fast. When you are developing games using this system you never see the compile taking place. One drawback of this system with Torque is that it isn't blatent when compile errors happen and you have to go back and look in the logs when you've made a bunch of changes. In most cases I've seen it will simply use the older .dso file and you'll be caught wondering why that echo/printf you just put in the code isn't appearing. As with most tools, once you get used to it, it is not really a problem. There is an editor called Torsion that will check/monitor your syntax, but I have not tried it. Everything I've read says it is highly recommended.

Torque Game Builder - TGB

Torque Game Builder (TGB) is another product I used in my game development class. It is a 2D version of the game engine that uses the same scripting language as the Torqe Game Engine (TGE) which is 3D.

Torque Game Builder was much more polished as a product, but it doesn't include source with the indie or edu license which is a disappointment, but not a good reason not to use it. This class was supposed to be a 3D class, but I did use the TGB for two weeks at the beginnning of class to give students an easier introduction to the scripting language. It was a lot easier to deal with the scripting language without the added third dimension. Once you add that third dimension everything gets more complicated.

Another big difference between the two is that TGB has a much better physics enginee. The physics engine in TGE is not as robust, but it does work for most FPS style games. The TGB physics engine has all the bells and whistles you would expect. As with TGE, TGB includes a multiplayer networking engine at it's core. Even single player games would have the networking code attached at the core. It's not a lot of over head, just the design for multiplayer at it's core. If you are going to develop a multiplayer game I do suggest buying the full license ($495) so you have the source and can run multiple clients on the same machine during development.

I think the TGB is very easy to learn and a great platform for building 2D games. For $100 there is no comparison.

Motivating students with a contest

A $100 EB gift card prize goes a long way in motivating a group of students. Sure it costs me a large percentage of the money I make teaching the class, but if I cared about the money I wouldn't teach the class in the first place. Adjunct teaching doesn't pay, at least not for me. I love to teach and the little I do make is just an added bonus.

I've done the contest once before and the work was amazing. This year I've upped the ante and invited a bunch of execs and hiring mangers from local game companies to be the final judges. This will be a great opportunity for the students to show their talent and for these game company folks to hire amazing young talent. It also motivates the students to spend extra time on their projects which is the only way to learn to program. All sides are primed and ready and it seems like the perfect matchup so far.

We still have 6 more weeks of development time left for the students, but after two weeks officially working on their final projects I am throughly impressed with the results. This is going to be much better than last year.

For those that are worried about it, the contest placing has no bearing on the grade for the students' final projects. I'll grade under the same rules as the contest, but that grade is separate from contest placing.

Broader individual knowledge helps the entire team

More thoughts on the 3d game development class I'm teaching.I'm about halfway through the semester and I just stopped giving 'busy work' assignments. Everyone is working on their own projects. The last busy work assignment I gave I introduced them to the installer. My choice of installer is NSIS, since it's free and something I have used on other commercial projects.

What does this have to do with a Game Development class? A ton. From the very first busy work assignment I forced my students to think in terms of a full cycle game. Everything they turned in had to have a splash page, a main menu and a way to cycle back to the main menu. The installer extends this concept of a full cycle game. Isn't this what they are going to deal with in the real world?

Most gaming books seem to only focus on the mechanics of the actual games, but to me that is only about 30% of the overall work that needs to get done. The real work is in the details and those details really matter. As an added bonus, once this class is over each of my students will have an full game with an installer they can give to a potential employer or put on a portfolio website. These students will have a distinct advantage over someone that just says they took a game development class.

To me this has a lot to do with getting a job, but it also has to do with the reality we all face. It is okay to specialize in one area of a project, but you still need to understand a little about the entire process. If everyone has broader knowledge the team will function more efficiently and increase the value of the products you create. Thus increasing the value of the individual to the team. I'm trying to train students I would want to have on my own team.

Blender. Free 3d modelling tool

As I mentioned in the previous post, I'm using Blender for modelling in my 3D game development class I'm teaching. I think Blender is great and the best value for the price (free!) of any modelling tool available. That said, it isn't for everyone. I did a full lecture on Blender and found that my love of Blender is related to my love of the text editor vi. In fact I used this opportunity to give the students a free introduction to vi. If you hate vi and think it is the worst editor ever, I guarantee you will not like Blender. If you like (or simply accept) vi then you will probably find that once you know about 20 key combos you'll be proficient with all things Blender.

Once I learned those key combinations I found that it is the fastest modelling tool I have ever used. I actually love the interface. I still find some process require a revisit of the documentation (especially for animations), but once I have them down it is fast.

The best way I found to learn Blender is with this set of Blender video tutorials.

The next best piece of documentation is this Blender Wiki book.The third place is the official Blender documentation.

If you have some extra time on a new modelling project give Blender a week and I think you will be hooked.

3d game development tools and Torque

The tools we chose for the game development class were driven mostly by the choice of books, but many of them are cheap/free and industrial strength as well and I would use most of them on my own projects even if I had some sort of budget. The engine we are using is Torque, but all these tools would be useful no matter which engine you use.

PaintShopPro is a great paint program. The first edition of the book used this tool, while the second edition uses Gimp. Since I already had a number of students in an earlier class that had used PSP I chose to stick with it. Also, it is my favorite paint program and in my opinion better than Photoshop for everything except CMYK. I've done a ton of image and print work over the years and PSP is an amazing value. Corel bought it from an independent developer a few years ago and I've been expecting a $400 price increase. I'm sure I'll grudgingly switch to Gimp if that happeens.

Milkshape is the tool used in the book and we made sure it was available for the students. It's not the best 3D tool by a long shot. It is missing a lot of features which also makes it a lot easier to learn. A double edged sword, but still a great value for $25.

For texture mapping you have to used a second tool called UVMapper. It's free and easy to use.

QuArk (Quake Army Knife) (free) is the tool we used to create interiors. Interriors are BSP trees that have a lot of properties that speed up rendering and collision detection. The cost is that the tools that do BSP are all very confusing and QuArk is no different. If you use QuArk for Torque, make sure you read the PDF tutorial that comes on the Game Programming All In One CDROM (it's not printed in the book any longer). It is a great tutorial that will take a lot of the guess work out of a confusing UI. Also, make sure you download QuArk from the Garage Games site and not the one main site as it's already configured for Torque. The Unreal editor is a BSP editor and it is just as confusing. Just because you pay more you are not going to find a good BSP editor.

Audacity (free) is not my first choice of audio tools, but my first choice (CoolEdit by Syntrillium) was purchased by Adobe and the price raised by $400. I'm not one to pay hefty fees for software and have found that I can live with Audacity. I'm going to be really mad if Corel does the same thing with PaintShopPro.

Blender (replacement for Milkshape) is my last tool of choice and it is a controversial one. You either love it or hate it. Blender was a commercial 3D editing tool that moved into the open source community driven world and is well updated and supported. It is absolutely free. That's not the controversial part. You either love it or you hate it as the UI takes a little getting used to, but once you have it down it is extremely fast. The commercial equivalent is 3D Studio Max and is used by 98% of the game studios. My only problem with it is the $3500 price tag. I'll do another blog entry just on Blender.

That's my list of (cheap/free) software to use in 3D game development.

Books to use with Torque

In choosing books for the game development class I am teaching we really only had three choices for the class. I don't belive I made the best choice with the limited time I had to choose and would choose differently now.These are the two books I would choose for the class if I had to choose again.

3D Game Programming All In One and Advanced 3D Game Programming All In One.

These two books compliment each other very well. The first book is more oriented towards a general overview and the tools to use and the second one has a much better focus on Torque Script and programming.

The other book that I would leave off the list is:The Game Programmers Guide To Torque

I thought this book would serve as a better reference, but it seems to be a wiki that was turned into a book and isn't detailed enough as a reference, or descriptive enough as a book. It jumps around too much and doesn't help give a clear understanding.