HPAVC/HPAVC CD-ROM.iso/pc/J4FTUT03.ZIP/temp/techtut/tut3/ptech3.txt

Text File | 1997-09-10 | 10.2 KB | 310 lines

 ========================================================================
                   Just4Fun Productions presents:

                      Part 3 of: the Techtutor
                       (Topics never covered)


                             HighScores
 ========================================================================

Introduction
============-
Welcome to part 3 of the Techtutor, this one is mainly for SuperFX users,
because it explains how to read a string using the keyboard. It does however
contains some information for beginners interested in putting a great
highscore table in their game...
For an example of a very stylish high-score, read TECH03.PAS

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Need more input...
==================-

First of all we'll need to get the name of the player, and the best way
would be to let him/her type it. One problem occurs when using the engine,
because we don't have the normal keyboard interupt...
We could ofcourse switch back to the old one, but it can be done different.
The Engine contains an array wich has the "names" of all the keys, and
we are going to use that array... For the example, take a look at the
GETINPUT procedure (tech03.pas) This procedure will get the input of the
player, and return it. Note that this procedure could still use some work,
like checking on ESCAPE to exit the input, and it has a few bugs in it. But
the most important thing is shown, the checking on the correct key-pressed.

HighScore typecasting
=====================-

Before we code anything, we'll have to define a HIGHSCORE type like this:

     TYPE  TScore = record
            name   : string[8];
            score  : longint;
            level  : word;
            date   : Longint;
           end;

     VAR   HiScore  : array[1..15] of Tscore;


The example will record the following things about the new high-score:
 * Name of player, the most important item
 * Score of player, very nice to know...
 * Level reached, the level the player reached.
 * Date of game, this is to show when the game was played...
Ofcourse not all these are needed, but just use what you want in you'r
game, and simply erase the rest. Now that we have the type, we made an array
of 1..15, so we can record 15 players..again this can be changed for you'r
own desires.

Who makes the list...
=====================-

The next thing we should do is checking if the player has a new highscore.
To do this, we'll have to walk thru the existing list, and see if the
score is larger then the lowest...if it is we need to know if it's higher
then the next, and the next, and the next, etc...

{=-=-= Example =-=-=-=}
FUNCTION SeeHIScore(Nscore:longint;Nlevel:word):boolean;
VAR i,j  : byte;
    done : boolean;
    dow,hs      : word;
    tempD        : DateTime;

BEGIN
 SeeHiscore:=false;
 if Nscore<HiScore[15].score then exit;{ if score is lower than last
one,exit}
 i:=15;
 done:=false;
 repeat
    if Nscore>HiScore[i].score then dec(i) else Done:=true;
 until (i=0) or (done);
    inc(i);
    SeeHiScore:=true;
    for j:=14 downto i do HiScore[j+1]:=HiScore[j];
    with HiScore[i] do begin             { add new highscore }
         Name:=GetName;                  { get the name }

         score := Nscore;                { add score }
         level := NLevel;                { add level }
         GetDate(TempD.year,TempD.month,TempD.day,dow);
         GetTime(TempD.hour,TempD.min,TempD.sec,hs);
         PackTime(TempD,date);           { add date  }
    end;
END;
{=-=-= End of Example =-=-=-=}

This procedure will not only look if we got an highscore, it will also
add the new score to the list, and call the GETINPUT procedure for the name.

Show me, I wanna see it
=======================-

So now we got a high-score table...but we still can't see it. Showing the
table is the most simple thing in the SuperFX Engine, just walk thru the
table, and write the text on screen! You could, ofcourse, first draw a
background or something and then put the text "over" it. For the example
look at SHOWHISCORE. It will display the complete table (NOTE: this
procedure is different from the one found in the example, this one can be
used without the SuperFX engine).


{=-=-=-= Example =-=-=-=}
PROCEDURE ShowHIScore;  { for normal text-screens   untested!!! }
VAR i    : byte;
    zin  : string;
    Tdate: DateTime;
    ScoreOFS : byte;
BEGIN
 textcolor(7); textbackground(0); clrscr;
 ScoreOfs:=2;

 REPEAT
   gotoxy(1,1); write('NR');
   gotoxy(4,1,); write('Name');
   gotoxy(14,1); write('Score');
   gotoxy(20,1); write('Level');
   gotoxy(26,1); write('Time');
   gotoxy(36,1); write('Date');

   for i:=1 to 15 do begin
     with HiScore[i] do begin
          {
             Show NAME and rank
          }
          str(i,zin);
          while length(zin)<2 do zin:=' '+zin;
          zin:=zin+'. '+NAME;
    gotoxy(1,scoreofs+i); write(zin);
          {
            Show the Score
          }
          str(score,zin);
          while length(zin)<9 do zin:='.'+zin;
          gotoxy(4,scoreofs+i); write(zin);
          {
            Show the level
          }
          str(level,zin);
          gotoxy(20,scoreofs+i); write(zin);
          {
            Get the time of the played game
          }
          UnpackTime(Date,TDate);
          {
             Show the hour played
          }
          str(Tdate.hour,zin);
          while length(zin)<2 do zin:=' '+zin;
          zin:=zin+':';
          gotoxy(26,scoreofs+i); write(zin);
          {
            Show minutes
          }
          str(Tdate.Min,zin);
          while length(zin)<2 do zin:='0'+zin;
          gotoxy(29,scoreofs+i); write(zin);
          {
            Show month name
          }
          zin:=MNames[Tdate.Month];
          zin:=zin+'-';
          gotoxy(36,scoreofs+i); write(zin);
          {
            Show the day
          }
          str(Tdate.day,zin);
          while length(zin)<2 do zin:=' '+zin;
          gotoxy(40,scoreofs+i); write(zin);
          {
            Show the Year
          }
          str(Tdate.year,zin);
          gotoxy(43,scoreofs+i); write(zin);
     end;
   end;

 repeat until port[$60]<>156;
END;

{=-=-=-= End of Example =-=-=-=}

Loading the score
=================-

A highscore should ofcourse be saved to disk, so it can be loaded later
when the game is played again... so that's what we are going to do.
First of all we should be able to load the existing High-score table.
You could start loading the file, but what if the file does not exist?
so at the start of you'r game make sure you "fill" the high-score with
some fake values, but remember that the player has to be able to easily
get higher scores then the fake ones! Now we have to check if the file
exists, if it does we can safely start loading. Note that you don't go and
read in a loop from 1 to 15 (or 10), because maybe some one tinkered with
the scores and there might only be 4 highscores in the file. So keep track
of that..for an example look at the LOADSCORES procedure.
Note: You could add a nice thing here, because if you find somethings wrong
with the highscore file, you could create a new blank table, and put in very
hi scores the list...just a thought.

{=-=-=-= Example =-=-=-=}
PROCEDURE LoadScores;
VAR f : file;
    i : byte;
    dow,hs      : word;
    tempD       : DateTime;
BEGIN
 assign(f,'hiscore.his');       { name of the hiscore file }
 {$I-}
   reset(f,1);
 {$I+}
  if ioresult<>0 then begin     { No hiscore file found, so create one! }
     rewrite(f,1);
     Hiscore[01].score:=1500;  Hiscore[02].score:=1400;
     Hiscore[03].score:=1300;  Hiscore[04].score:=1200;
     Hiscore[05].score:=1100;  Hiscore[06].score:=1000;
     Hiscore[07].score:=0900;  Hiscore[08].score:=0800;
     Hiscore[09].score:=0700;  Hiscore[10].score:=0600;
     Hiscore[11].score:=0500;  Hiscore[12].score:=0400;
     Hiscore[13].score:=0300;  Hiscore[14].score:=0200;
     Hiscore[15].score:=0100;
     for i:=1 to 15 do begin
         with HiScore[i] do begin
              Name:='ME!';
              Level:=$101;
              GetDate(TempD.year,TempD.month,TempD.day,dow);
              GetTime(TempD.hour,TempD.min,TempD.sec,hs);
              PackTime(TempD,date);
         end;
         blockwrite(f,hiscore[i],sizeof(TScore));
     end;
     close(f);
     exit; { done the loading, so exit }
  end;
 i:=1;
 while (not eof(f)) and (i<16) do begin
       blockread(f,hiscore[i],sizeof(TSCORE));
       inc(i);
 end;
 close(f);
END;
{=-=-= End of Example =-=-=}


Saving the score
================-

After the player get's a new high-score, it's best to save it at once.
because if the game crashes the player might loose it's score, and be
pissed off at the game, and the programmer (you!). The saving is the easiest
of all procedures:
 * Open a NEW file
 * Loop thru the scores, saving them one by one...
I know that you should do some error checking, because if the game is
run from CD, you won't be able to save!

{=-=-= Example =-=-=}
PROCEDURE SaveScores;
VAR f : file;
    i : byte;
    dow,hs      : word;
    tempD        : DateTime;
BEGIN
 assign(f,'hiscore.his');
 rewrite(f,1);
 for i:=1 to 15 do blockwrite(f,hiscore[i],sizeof(TSCORE));
 close(f);
END;
{=-=-= End of Example =-=-=-=}


That's all folks
================-

Well that was a brief explanation about high-scores, and how to
implement them. I know that most people won't even look at this because
they think it's to simple for them, well they had to learn it somewhere
and might not even be doing it that correctly, who knows? But for the
beginning game-programmers this could be a usefull text, and for the SuperFX
Engine users it handy to know who to read the keyboard keys...

Next Tech topic: Collisions


PeeBee - September 10th '97