Dynamic in-game object creation and manipulation

[Tomi]

I speak Hungarian too , but even I find it difficult to read code that is not in english.
Your english is pretty good, it would help everyone here if you would develop your code in english.

Maybe I will so, but it is better for me writing in Hungarian so far, because I can separate my variables and other things better.

[SilverWarior]

Maybe I will so, but it is better for me writing in Hungarian so far, because I can separate my variables and other things better.

I agree with Robert's suggestion.
Having your code written in English does have a great benefit that you can just simply copy and paste part of your code when you are seeking help from others.

I myself am not native English speaking person and used to write my code in Slovenian (my native language) but eventually I figured out that it is better if I write my code in English instead. Why?
When I have all of my code written in English it allows my brains to kind of switch into "English mode" where even most of my thought process is done in English. I know it sounds a bit weird.
But when I have parts of the code written in Slovenian my brain stays in "Slovenian mode" where I'm forced of constantly having to translate English parts of the code or documentation into Slovenian which I think it slows down the thought process a bit.
And sometime it might even happen that my brain would en up being in "English mode" and I would end up constantly translating my Slovenian code into English. And yes I know that this seems even weirder.

[Tomi]

No, not so weird, SilverWarior, after all you are right: if I would like help from an English-speaking programmer community, the best is when I write my codes totally in English in order to better understand.
Therefore today I have made a small program, which is focusing the "bullet appearing" problem:

unit Unit1;


{$mode objfpc}{$H+}


interface


uses
  Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, ExtCtrls;


type


  { TForm1 }


  TForm1 = class(TForm)
    Timer1: TTimer;
    procedure FormClose(Sender: TObject; var CloseAction: TCloseAction);
    procedure FormCreate(Sender: TObject);
    procedure Timer1Timer(Sender: TObject);
  private
    { private declarations }
  public
    { public declarations }
  end;


type TGameObject=class(TObject)
  private
  public
    xplace,yplace,celx,cely,movedir: integer;
    itsimage: TBitmap;
    canshoot: boolean;
    shoottimer: byte;
    constructor create(xplacehere,yplacehere: longint; imagehere: Tbitmap);
end;


var
  Form1: TForm1;
  backgroundimg,bulletimg,spaceshipimg: TBitMap;
  spaceship: TGameObject;
  bullet: array [0..100] of TGameObject;
  numofbullets: integer;


implementation


{$R *.lfm}


constructor TGameObject.create(xplacehere,yplacehere: integer; imagehere: Tbitmap);
begin
        xplace:=xplacehere;
        yplace:=yplacehere;
        itsimage:=imagehere;
end;


{ TForm1 }


procedure TForm1.FormCreate(Sender: TObject);
var initialmovedir: shortint;
begin
  backgroundimg := TBitmap.Create;
  backgroundimg.LoadFromFile('kepek/urhatter.bmp');
  bulletimg:=TBitMap.Create;
  bulletimg.LoadFromFile('kepek/ell_lov.bmp');
  bulletimg.transparent:=true;
  spaceshipimg:=TBitMap.Create;
  spaceshipimg.LoadFromFile('kepek/ell1.bmp');
  spaceshipimg.transparent:=true;
  randomize;
  if round(random(2))=1 then initialmovedir:=-2 else initialmovedir:=2;
  spaceship:=TGameObject.create(Form1.ClientWidth div 2,spaceshipimg.height,spaceshipimg);
  spaceship.movedir:=initialmovedir;
  spaceship.shoottimer:=100;
  spaceship.canshoot:=false;
  numofbullets:=0;
end;


procedure TForm1.FormClose(Sender: TObject; var CloseAction: TCloseAction);
begin
  backgroundimg.free;
  bulletimg.free;
  spaceshipimg.free;
end;


procedure TForm1.Timer1Timer(Sender: TObject);
var i,j: integer;
begin
  Form1.Canvas.StretchDraw(Rect(0, 0, ClientWidth, ClientHeight), backgroundimg);
  if spaceship.shoottimer>0 then dec(spaceship.shoottimer) else spaceship.canshoot:=true;
  if (spaceship.xplace+spaceship.movedir>=ClientWidth-spaceshipimg.width) or (spaceship.xplace+spaceship.movedir<=1) then
  begin
       if spaceship.yplace+spaceshipimg.height<ClientHeight then
          spaceship.yplace:=spaceship.yplace+spaceshipimg.height
       else
           spaceship.yplace:=spaceshipimg.height;
       spaceship.movedir:=-spaceship.movedir;
  end
  else
  begin
       spaceship.xplace:=spaceship.xplace+spaceship.movedir;
  end;
  Form1.Canvas.Draw(spaceship.xplace,spaceship.yplace,spaceshipimg);
  if (round(random(50))=1) and (spaceship.canshoot=true) then
  begin
       bullet[numofbullets]:=TGameObject.create(spaceship.xplace,spaceship.yplace,bulletimg); {!!!WRONG!!!}
       inc(numofbullets);
       spaceship.canshoot:=false;
       spaceship.shoottimer:=100;
  end;


  if numofbullets>0 then
  begin
       i:=0;
       while i<numofbullets-1 do
       begin
            if bullet[i]<>nil then
            begin
                if bullet[i].yplace>ClientHeight then
                begin
                    freeandnil(bullet[i]);
                    if i=numofbullets-1 then
                            dec(numofbullets)
                    else
                    begin
                            for j:=i+1 to numofbullets-1 do
                                bullet[j-1]:=bullet[j];
                            dec(numofbullets);
                            dec(i);
                    end;
                end
                else
                begin
                    bullet[i].yplace:=bullet[i].yplace+4;
                    Form1.Canvas.Draw(bullet[i].xplace,bullet[i].yplace,bulletimg);
                end;
            end;
            inc(i);
       end;
  end;
end;


end.

Maybe somebody can help me...

[User137]

The last loop is still bothering me, it is needlessly complicated and could make errors. Like i suggested earlier, here's how it would look:

  for i:=numofbullets-1 downto 0 do
  begin
    bullet[i].yplace:=bullet[i].yplace+4;
    if bullet[i].yplace>ClientHeight then
    begin
      bullet[i].Free;
      dec(numofbullets);
      bullet[i]:=bullet[numofbullets];
    else begin
      Form1.Canvas.Draw(bullet[i].xplace, bullet[i].yplace, bulletimg);
    end;
  end;