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Thread: FreePascal and JEDI-SDL - A first game template

  1. #1
    Legendary Member cairnswm's Avatar
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    Nov 2002
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    Randburg, South Africa
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    1,537

    FreePascal and JEDI-SDL - A first game template

    I've got FreePascal and JEDI-SDL working on my PC. So the first thing I start doing is getting a nice template ready to use for making games (I'll look into getting a simple game done with the template over the weekend.

    Sorry about it being a bit messy but its 10pm and bed time

    [pascal]
    program SDLTemplate;

    uses
    SysUtils,
    Logger,
    SDL;

    // Copyright 2004 CairnsGames S.A.
    // Can be used for any purpose - if you actually sell it at least
    // let me know
    // (Also known as the PLMK license!)

    const
    TICK_INTERVAL = trunc(1000 div 20);
    VERSION_NO = '1.0';
    TITLE = 'SDL (FreePascal) Game Template';
    AUTHOR = 'William Cairns';

    type
    TScene = (scTitleProcess, scGameSetup, scGameProcess, scEndProcess, scFinish);
    TGameImage = Class
    Name : String;
    ImageSurface: PSDL_Surface;
    Constructor Create;
    Procedure LoadFromFile(FileName : String);
    Procedure SetGamePallette;
    Procedure Draw(X,Y : Integer);
    End;
    TBase = Class
    SrcRect, DestRect: TSDL_Rect;
    x, y: integer;
    Constructor Create;
    procedure Move; Virtual; Abstract;
    procedure Remove; Virtual; Abstract;
    procedure Draw; Virtual; Abstract;
    End;
    var
    SurfaceLost: boolean = false;
    next_time: UInt32 = 0;
    Surface, Background: PSDL_Surface;
    Event: TSDL_Event;
    colors: array[0..255] of TSDL_Color;
    Scene: TScene;
    ScreenMode: cardinal = 0;
    Images : Array[0..0] of TGameImage;

    Constructor TGameImage.Create;
    Begin
    End;

    Procedure TGameImage.LoadFromFile(FileName : String);
    Begin
    If Name = '' then
    Name := FileName;
    ImageSurface := SDL_LoadBMP(PChar(FileName));
    if ImageSurface = nil then
    begin
    Log.LogError(Format('Couldn''t load image : %s',[SDL_GetError]), 'Initialize');
    end;
    SDL_SetColorKey(ImageSurface, SDL_SRCCOLORKEY or SDL_RLEACCEL or SDL_HWACCEL,
    SDL_MapRGB(ImageSurface.format, 192, 192, 192));
    End;

    Procedure TGameImage.SetGamePallette;
    Var
    I : Integer;
    Begin
    for i := 0 to 255 do
    Colors[i] := ImageSurface.Format.Palette.Colors[i];
    SDL_SetColors(Surface, @Colors, 0, 256);
    End;

    Procedure TGameImage.Draw(X,Y : Integer);
    Var
    SrcRect, DestRect: TSDL_Rect;

    Begin
    SrcRect.y := 0;
    SrcRect.x := 0;
    SrcRect.w := 480;
    SrcRect.h := 64;
    DestRect.x := X;
    DestRect.y := Y;
    SDL_BlitSurface(ImageSurface, @SrcRect, Surface, @DestRect);
    End;

    Constructor TBase.Create;
    Begin
    End;


    procedure Initialize(Flag: cardinal);
    var
    Error: boolean;
    begin
    Error := false;
    if SDL_Init(SDL_INIT_VIDEO) = -1 then
    begin
    Log.LogError(Format('Could not initialize SDL : %s',
    [SDL_GetError]), 'Initialize');
    SDL_Quit;
    halt(1);
    end;

    Surface := SDL_SetVideoMode(640, 480, 8, SDL_SWSURFACE or SDL_HWPALETTE or
    Flag);
    if Surface = nil then
    begin
    Log.LogError(Format('Couldn''t set 640x480x8 video mode : %s',[SDL_GetError]), 'Initialize');
    Error := true;
    end;
    if not Error then
    begin
    // Start Loading Images
    Images[0] := TGameImage.Create;
    Images[0].LoadFromFile('images/CairnsGamesLogo.bmp');
    Images[0].SetGamePallette;
    end;
    // Call SetGamePallette for one Image - require for setting background pallette
    // Create Background Image
    if not Error then
    begin
    Background := SDL_CreateRGBSurface(SDL_SWSURFACE or SDL_HWPALETTE, 640, 480,
    8, 0, 0, 0, 0);
    if Background = nil then
    begin
    Log.LogError(Format('Couldn''t create surface: %s',
    [SDL_GetError]), 'Initialize');
    Error := true;
    end;
    SDL_SetColors(Background, @Colors, 0, 256);
    end;

    if Error then
    begin
    SDL_FreeSurface(Surface);
    // Free all images that were loaded
    SDL_Quit;
    Halt(1);
    end;

    SDL_WM_SetCaption(TITLE+' v' + VERSION_NO + ' by '+AUTHOR, nil);
    Log.LogError(TITLE+' v' + VERSION_NO + ' by '+AUTHOR, 'Initialize');

    // Do Any Program Initializations Here
    end;

    procedure Finalize;
    begin
    SDL_FreeSurface(Surface);
    SDL_FreeSurface(Background);
    // Free all Created Surfaces (Images that were loaded)
    // SDL_FreeSurface(ImageObject);
    SDL_Quit;
    end;

    procedure ToggleVideo;
    begin
    Log.LogError(IntToStr(ScreenMode), 'ToggleVideo');
    case ScreenMode of
    0:
    begin
    Finalize;
    ScreenMode := SDL_FULLSCREEN;
    Initialize(ScreenMode);
    SurfaceLost := true;
    end;
    SDL_FULLSCREEN:
    begin
    Finalize;
    ScreenMode := 0;
    Initialize(ScreenMode);
    SurfaceLost := true;
    end;
    end;
    end;

    procedure DrawBackground;
    var
    x: smallint;
    DestRect: TSDL_Rect;
    begin
    DestRect.x := 0;
    DestRect.y := 0;
    for x := 0 to 39 do
    begin
    // Draw the Background Image onto the Surface - Tiled etc
    // SDL_BlitSurface(Lines, nil, Surface, @DestRect);
    //inc(DestRect.x, ;
    end;
    SDL_BlitSurface(Surface, nil, Background, nil);
    end;


    function TimeLeft: UInt32;
    // Calculates time left until next screen refresh for fixed FPS systems
    var
    now: UInt32;
    begin
    now := SDL_GetTicks;
    if next_time <= now then
    begin
    next_time := now + TICK_INTERVAL;
    result := 0;
    exit;
    end;
    result := next_time - now;
    end;

    procedure DrawTitle;
    var
    DestRect: TSDL_Rect;
    begin
    DrawBackground;
    // Draw relevant Game Intro stuff. - Will be flipped in Title Process
    Images[0].Draw(64,64);
    end;

    procedure TitleProcess;
    begin
    { Draw title screen }
    DrawTitle;
    repeat
    while SDL_PollEvent(@event) > 0 do
    begin
    case event.type_ of
    SDL_QUITEV :
    Begin
    Log.LogError('Quit Event','TitleProcess');
    Scene := scFinish;
    End;

    SDL_KEYDOWN :
    begin
    case Event.Key.keysym.sym of
    SDLK_SPACE :
    Scene := scGameSetup;
    SDLK_ESCAPE :
    Scene := scFinish;
    SDLK_RETURN :
    begin
    Log.LogError('Return Key','TitleProcess');
    if (Event.Key.keysym.Modifier and KMOD_ALT <> 0) then
    ToggleVideo;
    end;
    end;
    end;
    end;
    end;
    { Do we redraw the screen? (Because ToggleFullscreen) }
    if SurfaceLost then
    begin
    Log.LogError('Surface Lost','TitleProcess');
    DrawTitle;
    SurfaceLost := false;
    end;
    // Do screen animations and Game Logic for Title Screen here

    SDL_Flip(Surface);
    SDL_Delay(TimeLeft);
    until Scene <> scTitleProcess;
    end;

    procedure DrawMap;
    begin
    // Draw In Screen Stuff Here
    end;

    procedure GameSetup;
    var
    x, y, h: integer;
    house: byte;
    SrcRect, DestRect: TSDL_Rect;
    begin
    Log.LogError('Enter','GameSetup');
    { draw gackground lines }
    DrawBackground; // Creates Background Image
    SDL_BlitSurface(Surface, nil, Background, nil); // Draw it to Main Screen
    // Do all Game Initilizations Here

    // Update the screen.
    SDL_Flip(Surface);
    SDL_Delay(TimeLeft);
    Scene := scGameProcess;
    end;

    procedure GameProcess;
    var
    Wait: integer;
    begin
    Wait := 0;
    repeat
    while SDL_PollEvent(@event) > 0 do
    begin
    case event.type_ of
    SDL_QUITEV :
    Begin
    Log.LogError('Quit Event','GameProcess');
    Scene := scFinish;
    End;

    SDL_KEYDOWN:
    begin
    case Event.Key.keysym.sym of
    SDLK_SPACE :
    begin
    end;

    SDLK_ESCAPE :
    Begin
    Scene := scTitleProcess;
    Log.LogError('ESC Key','GameProcess');
    End;

    SDLK_RETURN :
    begin
    Log.LogError('Return Key','GameProcess');
    if (Event.Key.keysym.Modifier and KMOD_ALT <> 0) then
    ToggleVideo;
    end;
    end;
    end;
    end;
    end;
    // Do game logic here

    if SurfaceLost then
    begin
    DrawBackground;
    DrawMap;
    SurfaceLost := false;
    end;

    SDL_Flip(Surface);
    SDL_Delay(TimeLeft);
    until Scene <> scGameProcess;
    end;

    procedure EndProcess;
    const
    Anim: array[0..3] of byte = (0, 1, 2, 1);
    var
    SrcRect, DestRect: TSDL_Rect;
    CanExit : Boolean;
    begin
    repeat
    // Do any game over logic here - Usually Timer based
    CanExit := True;
    SDL_Flip(Surface);
    SDL_Delay(TimeLeft);
    until CanExit;
    Scene := scTitleProcess;
    end;

    begin
    randomize;
    Initialize(ScreenMode);
    Scene := scTitleProcess;
    repeat
    case Scene of
    scTitleProcess: TitleProcess;
    scGameSetup: GameSetup;
    scGameProcess: GameProcess;
    scEndProcess: EndProcess;
    end;
    until Scene = scFinish;
    Finalize;
    end.
    [/pascal]

    To create this template I just stripped various parts out of the BlitzBomber Demo and packaged the Image code into a Class. (Sprites should be a different class library - this is to store images only).

    I'll post some followups on this as I get things done.

    (I will probably move the Image Class out into another unit by next time)
    William Cairns
    My Games: http://www.cairnsgames.co.za (Currently very inactive)
    MyOnline Games: http://TheGameDeveloper.co.za (Currently very inactive)

  2. #2

    FreePascal and JEDI-SDL - A first game template

    Hey great template! The only problem with it is it wont work.

    You need to replace all your

    Code:
    'Couldn''t
    with

    Code:
    'Could not'
    You just have 1 too many single quotes, which is why the code did not get syntax highlighted properly, so i dont believe it would actually compile
    Homepage - http://incubii.port5.com

  3. #3

    FreePascal and JEDI-SDL - A first game template

    Quote Originally Posted by Incubii
    You just have 1 too many single quotes, which is why the code did not get syntax highlighted properly, so i dont believe it would actually compile
    The syntax highlighter forgets that when you writes two single quotes right after each other then it will appear in the text as one quote..

    Very nice template :toocool:
    Peregrinus, expectavi pedes meos in cymbalis
    Nullus norvegicorum sole urinat

  4. #4
    Legendary Member cairnswm's Avatar
    Join Date
    Nov 2002
    Location
    Randburg, South Africa
    Posts
    1,537

    FreePascal and JEDI-SDL - A first game template

    This template has been updated a lot in my Simple 2D library (S2DL) that you can find a link to somewhere else on this site.

    I am bust getting S2DL 1.04 ready to release. Probably ready in about 2 weeks. It moves the game template into a class (sort of like delphis TApplication) which makes it easier to maintain and read.
    William Cairns
    My Games: http://www.cairnsgames.co.za (Currently very inactive)
    MyOnline Games: http://TheGameDeveloper.co.za (Currently very inactive)

  5. #5

    FreePascal and JEDI-SDL - A first game template

    Quote Originally Posted by Incubii
    You just have 1 too many single quotes, which is why the code did not get syntax highlighted properly, so i dont believe it would actually compile
    That is valid Pascal syntax for inserting a single quote into a string constant. The Pascal highlighter of this forum software cannot handle it though.

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