This file contains two parts. The first is SpaceMission technical support and the second is a short history lesson about Barbarian Minds Software. Of course nobody is going read the second part but it's included anyway! *********************************************************** *********************************************************** Part one - Space mission technical support *********************************************************** *********************************************************** Although I have written many programs in the past, I'm quite proud of this one. Not that it's the best thing ever coded but it turned out to be quite a reasonable game. Most important of all, it is the best ORGANIZED program I 've ever written. I spent more time with a pen and paper than with the computer. When I had my ideas written down in a clear manner, all I had to do is to punch it in. At the end, I had only one bug to face! But that is what good programming is all about. Planning ahead of time. If you expect to find a line by line technical report here, forget it. I don't have the time to explain a 20k program and another 30k of data line by line. Instead, I hope to describe the main ideas behind SpaceMission and how they were accomplished in AMOS. Another thing, this doc will not be much help to advanced programmers, as it is more suitable for novices who are trying to build better programs. Let's get down to some brain work! Leading concept: Dynamic Allocation. ----------------------------------- The Leading idea behind the whole program is Dynamic allocations. "What the hell is that?" I can here some of you say. Well, imagine you are standing in a bank with 16 clerks (big bank). Every customer goes to one of the windows, and when he finishes his actions HE FREES HIS POSITION TO THE NEXT IN LINE. That is what Dynamic allocation is all about. Freeing an unused position to someone else. The need to free locations comes when we are limited in resources. If that bank had an infinite amount of clerks, the customers would simply stand in their positions forever and let the others be served by other clerks. That is really an ideal situation, since in order to Dynamically allocate you need two actions. The first is to free the location and the second is to fill it with the next in line, while in infinite mode you only need one action (filling the next in line in.) What has that got to do with SpaceMission? If you think of the game for a second, you probably remember quite a large number of ships attacking you. Now, AMOS can handle only 16 AMAL interrupts at once. If I intended to move the Bobs using interrupts only, I would be able to handle only up to 16 bobs. That is where dynamic allocation comes in to play. In SpaceMission, each bob is turned off when it finishes its movement sequence, freeing its interrupt to the next bob in line. Putting it into code. --------------------- Well, In Space-mission, I used a 15 elements long array in order to maintain the condition of the different interrupts channel. An element which is equal to one means the channel is allocated while an element which is equal to zero means an disallocated channel. Let's say we want to see if a bob finished his movement so we can disallocate his interrupt: For _loop = 1 to 15 : Rem We need to loop through the whole Rem channels. If _Free_Channel(_loop)=1 :Rem_Free_channel() is the array which Rem Contain the interrupts condition. Rem we want to check only channels Rem which are considered allocated at Rem the moment. If ((Chanmv(_loop)=0) And (Chanan(_loop)=0)) : Rem If the Rem channel Rem is not moving Rem or animating Rem then.... _Free_channel(_loop)=0 : Rem DISALLOCATE IT! End If End If Next _loop That's one part. Now, how do we allocate?!?! Well, first we need to find a Disallocated channel and then allocate it: _dal_channel = 0 : Rem If a disallocated channel is found, Rem This verible will be different then Zero For _loop = 1 to 15 : Rem looping through all of the channels If _Free_channel(_loop)=0 : Rem Found a disallocated channel! _dal_channel = _loop : Rem get the Disallocated channel into Rem the element _dal_channel. _loop = 15 : Rem this little trick causes the loop to Rem Terminate at once. End If Next _Loop If _dal_channel > 0 : Rem Ah ha! we found a disallocated channel. _free_channel (_dal_channel) = 1 : Rem Allocate it.... End if Ok, Here is a complete program which uses this method. It will display 15 square bobs moving on the screen from side to side. Notice that after bob 15 no bobs are drawn until a bob leaves the screen. That's because there are no free channels to allocate. (The following example is included on the disk. The program is called Smex1.amos) Screen Open 0,320,200,8,Lowres | Opening a Screen. Dim _FREE_CHANNEL(15) | declaring the array. Cls 0 \ Bar 0,0 To 4,4 \ Getting a small Get Bob 1,0,0 To 4,4 \ square bob and Cls 0 - resetting the For _LOOP=1 To 15 / _free_channel() _FREE_CHANNEL(_LOOP)=0 / array. Next _LOOP / Double Buffer ' _START: '-------------------------------------------------- ' Disallocate a channel! ' For _LOOP=1 To 15 If _FREE_CHANNEL(_LOOP)=1 If((Chanmv(_LOOP)=0) and(Chanan(_LOOP)=0)) Bob Off _LOOP _FREE_CHANNEL(_LOOP)=0 End If End If Next _LOOP '-------------------------------------------------- ' Allocating a Channel ' _DISALLO=0 For _LOOP=1 To 15 If _FREE_CHANNEL(_LOOP)=0 _DISALLO=_LOOP _LOOP=16 End If Next _LOOP If _DISALLO>0 Bob _DISALLO,0,50,1 Channel _DISALLO To Bob _DISALLO Amal _DISALLO,"Move 320,0,320" Amal On _DISALLO _FREE_CHANNEL(_DISALLO)=1 Wait 5 End If Goto _START ' '--------------------------------------------------- The Actions database - Motor of attack waves. --------------------------------------------- Let's return to the real `life' bank and look at a day's work. People come in, finish their business and go out. Now, imagine you could control those people's actions. Imagine you could tell them when to get in, what to do, and when to leave. Then you would get something which could reassemble an attack zone in SpaceMmission. Ships come in whenever you decide, move in a certain form and get out. We can divide the process into two parts: One is timing and the second is movement form. First part first. How do we deal with timing? Well, the part in our program which gets the ships going is the allocation part. If we will could call it only when we want a ship on the screen then we are actually timing the ships entrance. For a timer we could use an increasing counter, but AMOS supplies us with access to the built in computer timer. 50 ticks of that timer equals a single second. We will use a few data statements to tell the computer when to call the allocation routine. (The following example is included on the disk. The program is called Smex2.amos) Screen Open 0,320,200,8,Lowres Dim _FREE_CHANNEL(15) Cls 0 Bar 0,0 To 4,4 Get Bob 1,0,0 To 4,4 Cls 0 For _LOOP=1 To 15 _FREE_CHANNEL(_LOOP)=0 Next _LOOP Double Buffer Timer=0 : Rem Most important, resetting the timer! Restore TIMEBASE Read ACTIONTIME : Rem here we read the first action time data Rem piece. ' _START: '-------------------------------------------------- ' Disallocate a channel! ' For _LOOP=1 To 15 If _FREE_CHANNEL(_LOOP)=1 If((Chanmv(_LOOP)=0) and(Chanan(_LOOP)=0)) Bob Off _LOOP _FREE_CHANNEL(_LOOP)=0 End If End If Next _LOOP '-------------------------------------------------- ' Check if time for next action arrived \ Here is the part ' \ where we sequence If((Timer/50)0 Bob _DISALLO,0,50,1 Channel _DISALLO To Bob _DISALLO Amal _DISALLO,"Move 320,0,320" Amal On _DISALLO _FREE_CHANNEL(_DISALLO)=1 End If Goto _START '-------------------------------------------------- ' The time base ' TIMEBASE: Data 3,5,6,8,10,12,13,14,15,16,17,20,22,24,26,30 As you probably noticed, SpaceMission many movement forms. Some ships comes from front, others from behind, bullets come right at you and if you got to higher levels you might even see ships who move in strange sine pattern.The movement patterns resemble the second part of the actions base. In SpaceMission, each data line is divided to two. The first item is the time of the action, and the others define the type of movement. Now, let's decide on two types of movements. The first will be a movement from left to right, and the other (number two) from the top of the screen to the bottom. See how few modifications to the previous program completes our task? (The following example is included in the disk. The program is called Smex3.amos) Screen Open 0,320,200,8,Lowres Dim _FREE_CHANNEL(15) Cls 0 Bar 0,0 To 4,4 Get Bob 1,0,0 To 4,4 Cls 0 For _LOOP=1 To 15 _FREE_CHANNEL(_LOOP)=0 Next _LOOP Double Buffer Timer=0 Restore TIMEBASE Read ACTIONTIME ' _START: '-------------------------------------------------- ' Disallocate a channel! ' For _LOOP=1 To 15 If _FREE_CHANNEL(_LOOP)=1 If((Chanmv(_LOOP)=0) and(Chanan(_LOOP)=0)) Bob Off _LOOP _FREE_CHANNEL(_LOOP)=0 End If End If Next _LOOP '-------------------------------------------------- ' Check if time for next action arrived... ' If((Timer/50)0 If ACTIONTYPE=1 \ The different attack Bob _DISALLO,0,50,1 \ pattern require End If | different start If ACTIONTYPE=2 | position Bob _DISALLO,100,0, / End If / Channel _DISALLO To Bob _DISALLO If ACTIONTYPE=1 - first action type, Amal _DISALLO,"Move 320,0,320" move from right to End If left. If ACTIONTYPE=2 - second action type, Amal _DISALLO,"Move 0,200,200" move from top to End If bottom. Amal On _DISALLO _FREE_CHANNEL(_DISALLO)=1 End If Goto _START '-------------------------------------------------- ' The Action base - First data item represent the time ' and the second represent the attack pattern. ' TIMEBASE: Data 3,1 Data 5,1 Data 6,1 Data 8,1 Data 10,2 Data 12,1 Data 13,2 Data 14,2 Data 15,1 Data 16,2 Data 17,1 Data 20,2 Data 22,2 Data 24,2 Data 26,1 Data 30 In Space-mission itself, a data line as much more complicated. For example: data 200 , 12 , 3 , 200 |the time of |The action type - | The bob | The amount of | the action.| for example move | Index in the | steps needed | | move from left to | bob's bank | for the bob | | right. | To allow | to get from | | | different bobs| left to | | | assigned to | right. this | | | the action. | allow | | | | different | | | | speed assigned | | | | to the action. (This is only an example. not an actual part of space-mission.) Collisions ---------- In realty, only 12 channels are assigned to the enemy bobs in space mission. The first bob is your space ship, bobs number 2 to 4 are the bullets you shot. This mechanism of deciding what channels are assigned to which function make it easy to write collision detection routines. For example, if bob 1 collide with anything from channels 5 and above ( col = bob col (1, 5 to 16)) then my ship fried itself on an enemy ship. On the other hand, if one of my bullets (channels 2 to 4) hit an enemy ship (channels 5 and above) then I can smile as the enemy ship burns beautifully into the dark space. This is the real beauty about the whole system. After I let a bob go, I don't really know what happens with it, I don't have to keep it's coordinates, and can totally ignore it's behavior. I *DO* have to make periodical checks to see if it collided into something. Even when that happenes, I don't really know where on the screen the collision occurred, neither do I care! All I have to check is what channel bumped into what channel and if some result should emerge from it (explosion sound, an animation sequence, a score update, etc.) As for how to program those, well, I will leave this to your vivid imagination. Problems during coding. ----------------------- Okay people, let's admit it (and I know some people are not going to like this statement.) AMOS is relatively a slow language. No, not compared to other basics but to the more popular languages such as C and assembler. If I have any sort of problems in this game it was the speed of its execution. Since the machine has to control so many blitter objects at once, the execution of the original program is majorly decreased. I started noticing the problem when the bullets went right through the enemy ships without blowing them up. They simply passed each other before the computer got to the collision detection routines. I had to use an UPDATE EVERY 2 command to make the computer access the interrupts last (which makes the program run a little faster) but as the program got bigger, this has also proven to be of little help. The compiled program does much better, but in some rare cases it still misses. Well, that's about it for the ideas behind the program. There are of course many more points to look over in SpaceMission, and many more problems to face, but I trust you'd like to try them out for yourselves. The source code, by the way, is available upon request from me by sending mail either to broner@black.bgu.ac.il or by snail mail to Gal-on Broner P.O. Box 5418 Beer-sheva, Israel. don't forget to add a blank formatted disk inside the envelope..... ************************************************************* ************************************************************* Part two - History of barbarian minds. ************************************************************* ************************************************************* Barbarian minds group was forms back in 1986 by two members - Gal-on Broner and Yuval miinster. It's main idea was creating games and puzzles who stress the thinking helmet to it's limits. We had an *pple computer back then and we weren't great programmers. Well, we are not great programmers today, but we did make quite a giant step since then. The group got bigger along the years and expanded to other computers as well. The Amiga section of the group is headed by Gal-on Broner, writer of Space mission and the technical support. In the end of 1992, at one of the holidays, Barbarian Minds changed its face. First, the name was changed to Barbarian Minds Software. We felt that we are capable of creating better and more professional programs than before, and the change of name is a small mark of a big step forward. Barbarian minds will release at a faster pace public domain and Testware programs. In cases where money will be requested, we will make sure that the software really deserves it and the sums will be truly lower than other Shareware/Testware programs on the market. One of Barbarian Minds main projects is the AmoNER magazine. Although is has had some problems during its creation, it is now beginning to gain the final touch which requires a more stable distribution. Please keep in touch with us. We would like to hear your comments. Addresses appear in the policy guidelines available on the AmoNER Disks.