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Thread: Andorra 2d , adding very very basic gravity (sorta)

  1. #1

    Andorra 2d , adding very very basic gravity (sorta)

    Hello,

    I'm trying to add some very basic gravity to my figure in andorra 2d ( this is a very early stage... trying to make it so that I understand everything... ).

    Currently I'm doing it like this : (only falling down ...nothing else, constant speed for now, nothing fancy)

    It kinda works wich makes me happy, but not the way I wanted it to... my character falls down the moment he is not on a Platform, but the fact that I can move while falling, if I go back and collide with the Platform I'm stuck... (but now that I think about it , this problem might go away if I finish up the part where I can't enter a platform from any angle..., hm I think it wont be a problem if I prevent my character from Entering inside the platform...currently it's not implemented...)

    Code:
     
     unit Main;
    interface
    uses
      Windows,Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
      Dialogs, AdDraws, AdClasses, AdTypes, AdPerformanceCounter, AdDevIL,AdSprites;
      type
      //Types that are used to tell the character which key has been pressed
      TKey = (kyUp, kyDown, kyLeft, kyRight);
      TKeys = set of TKey;
      TPlatform = class(TImageSprite)
        private
        protected
          procedure DoMove(TimeGap: Double); override;
          procedure DoCollision(Sprite:TSprite; var Done:boolean); override;
        public
          constructor Create(AParent:TSprite);override;
        end;
      TSnow = class(TImageSprite)
        private
        protected
          procedure DoMove(TimeGap: Double);override;
        public
          Speed : double;
          constructor Create(AParent:TSprite);override;
        end;
      TBlurp = class(TImageSprite)
        private
        FKeys:TKeys;
        X_Direction:double;
        isfalling:boolean;
        protected
          procedure DoMove(TimeGap: Double);override;
          procedure DoCollision(Sprite:TSprite; var Done:boolean);override;
        public
          constructor Create(AParent:Tsprite);override;
          procedure SetKeys(Keys:TKeys);
        end;
      TForm1 = class(TForm)
        procedure FormCreate(Sender: TObject);
        procedure FormDestroy(Sender: TObject);
        procedure FormKeyDown(Sender: TObject; var Key: Word;
          Shift: TShiftState);
      private
        { Private declarations }
        procedure AddHo;
      public
        { Public declarations }
        AdDraw:TAdDraw;
        AdSpriteEngine:TSpriteEngine;
        AdImageList:TAdImageList;
        AdPerCounter:TAdPerformanceCounter;
        AdPixelCollisionTester: TAdSpritePixelCollisionTester;
        Blurp:TBlurp;
        procedure Idle(Sender:TObject; var Done:boolean);
      end;
    var
      Form1: TForm1;
      Ido,Ido2 : integer;
      ActTime : double;
    implementation
    {$R *.dfm}
    procedure TBlurp.SetKeys(Keys: TKeys);
    begin
      if Keys = FKeys then exit;
      FKeys := Keys;
      if kyRight in Keys then x_direction:=1.5;
      if kyLeft in Keys then x_direction:=-1.5;
     { if kyUp in Keys then Y:=Y-2;
      if kyDown in Keys then Y:=Y+2;}
      if Keys = [] then x_direction:=0;
    end;
    procedure TForm1.AddHo;
    begin
      with  TSnow.Create(AdSpriteEngine) do
        begin
          case random(3) of
            0:
              begin
                Image := AdImageList.Find('Ho');
                Speed := 1.1;
              end;
            1:
              begin
                Image := AdImageList.Find('Ho2');
                Speed := 0.5;
              end;
            2:
              begin
                Image := AdImageList.Find('Ho3');
                Speed := 2.1;
              end;
     
          end;
          X := random(640);
          Z := 1;
        end;
    end;
    
    constructor TPlatform.Create(AParent: TSprite);
    begin
      inherited;
    end;
    constructor TBlurp.Create(AParent: TSprite);
    begin
      inherited;
    end;
    constructor TSnow.Create(AParent: TSprite);
    begin
      inherited;
    end;
    
    procedure TSnow.DoMove(TimeGap: Double);
    begin
      inherited;
      Y:= Y + (0.1+Speed);
      case random(2) of
    {    0:  X:=X+0.2; }
        1:  X:=X-0.2;
      end;
      if X > 640-Image.Width then X:=0;
      if Y > 480 then
        begin
          Randomize;
          Y:=0;
          X:=random(640);
        end;
    end;
    procedure TBlurp.DoMove(TimeGap: Double);
    begin
      inherited;
      X:=X+X_direction;
      if X <= 0 then X:=0;
      if X > 640-Image.Width then X:=640-Image.Width;
      if Y < 0 then Y:=0;
      if Y > 480-Image.Height then Y:=480-Image.Height;
      Collision;
    end;
    procedure TPlatform.DoMove(TimeGap : Double);
    begin
      inherited;
      Collision;
    end;
    
    procedure TBlurp.DoCollision(Sprite:TSprite; var Done:boolean);
    begin
      if Sprite is TSnow then
        begin
          TSnow(Sprite).Dead;
        end;
      if Sprite is TPlatform then
        begin
          isFalling:=false;
        end;
    end;
    procedure TPlatform.DoCollision(Sprite:TSprite; var Done:boolean);
    begin
      if Sprite is TSnow then
        begin
          TSnow(Sprite).Dead;
        end;
    end;
     
    
    procedure TForm1.FormCreate(Sender: TObject);
    var i: integer;
    begin
      ido:=0;
      ido2:=1;
      AdPerCounter := TAdPerformanceCounter.Create;
      AdDraw := TAdDraw.Create(self);
      AdDraw.DllName := 'AndorraDX93D.dll';
     with AdDraw.Display do
        begin
        {  Width := 640;
          Height := 480;
          BitDepth := ad16Bit; //The colour depth. The values "ad16Bit" and "ad32Bit" are allowed here.
          DisplayMode := dmFullscreen; }
        end;
    
    if AdDraw.Initialize then
      begin
        Application.OnIdle := Idle;
        AdImageList := TAdImageList.Create(AdDraw);
        AdImageList.LoadFromFile('BackGround.ail');
    
        //create the SpriteEngine
         AdSpriteEngine := TSpriteEngine.Create(nil);
         AdSpriteEngine.Surface := AdDraw;
        //Create the collision tester
        AdPixelCollisionTester := TAdSpritePixelCollisionTester.Create(AdDraw);
        //create TImageSprite
        Randomize;
        for i := 0 to 30 do
          begin
            with TPlatForm.Create(AdSpriteEngine) do
              begin
                Image := AdImageList.Find('Kocka');
                X:= X+(i*16);
                case i of
                  0..9: Y:=300;
                  10..19: Y:=350;
                  20..30: Y:=400;
                end;
              end;
          end;
            Blurp := TBlurp.Create(AdSpriteEngine);
            with Blurp.Create(AdSpriteEngine) do
              begin
                Image := AdImageList.Find('Blurp');
                X := 0;
                Y := 250-Image.Height;
                Z := 1;
                CollisionTester := AdPixelCollisionTester;
                SetKeys([]);
                isfalling:=true;
              end;
     
    
        // ************* hater *********************************
      end
     else
      begin
         ShowMessage('Error while initializing Andorra 2D. Try to use another display'+
                   'mode or use another video adapter.');
        halt; //<-- Completely shuts down the application
      end;
    end;
    procedure TForm1.Idle(Sender: TObject; var Done: boolean);
    var keys: TKeys;
     begin
       if AdDraw.CanDraw then // Only continue, if drawing is possible
       begin
        ido:=ido+ido2;
        AdPerCounter.Calculate;
        AdPerCounter.MaximumFrameRate:=60;
    
        AdDraw.ClearSurface(clBlack); // Fill the surface with black color
        AdDraw.BeginScene;
        // Here you need to perform all drawing operations later
        ActTime := ActTime + AdPerCounter.TimeGap;
        if ActTime > 25 then
        begin
         keys := [];
          if GetKeyState(VK_LEFT) < 0 then keys := keys + [kyLeft];
          if GetKeyState(VK_RIGHT) < 0 then keys := keys + [kyRight];
       {   if GetKeyState(VK_UP) < 0 then keys := keys + [kyUp];
          if GetKeyState(VK_DOWN) < 0 then keys := keys + [kyDown]; }
          Blurp.SetKeys(Keys);
          ActTime := 0;
        end;
        if Blurp.isfalling = true then
          begin
            Blurp.Y:=Blurp.Y+1;
          end;
        Blurp.isfalling:=true;
     
        if ido >= 50 then
          begin
            if AdSpriteEngine.CountOfClass(TSnow) < 680 then
              begin
                AddHo;
                ido:=0;
                ido2:=ido2+1;
              end;
            if ido >= 50 then ido:=50;
          end;
        AdSpriteEngine.Draw;
        AdSpriteEngine.Move(25/1000);
        AdSpriteEngine.Dead;
        // debug
        AdDraw.Canvas.Textout(0,20,'Ho: '+inttostr(    AdSpriteEngine.CountOfClass(TSnow)));
        AdDraw.Canvas.Textout(0,40,'Ido: '+inttostr(Ido));
     
        AdDraw.EndScene;
        AdDraw.Flip; // Draws you result on the screen. Otherwise, you would not see anything
       end;
      Done := false; // Important, otherwise the function will not be called in every loop
     end;
    procedure TForm1.FormDestroy(Sender: TObject);
    begin
       AdSpriteEngine.Free;
       AdImageList.Free;
       AdPerCounter.Free;
       AdDraw.Free;
    end;
    procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word;
      Shift: TShiftState);
    begin
      if Key = VK_ESCAPE then Close;
    end;
    end.
    I've attached my code for review, I'm still in the process of learning so keep that in mind, I'm open to suggestions, cause there are probably a 100 things I'm doing wrong here , anyway I've started it real simple this time... first I've created a real simple wheel sprite with Sprite Class, created 10 wheels and made em move at different speeds... with different animations in each direction... then I've started to experiment with falling down objects...and came up with this snow effect (which I think is kinda great ) , then managed to get my first chacter moving (that part I'm not sure if I'm doing it the best way...) .... I'm trying to reverse the andorra 2d tutorials (demos) to very small steps (parts) so that I can better understand it...

    Anyway I've attached the executable... so you can see what I mean, I think if I prevent my character from moving inside the platform this very basic gravity will be fine for now. (I know there are far better gravitys like in the Traveller's unDelphix Platform Game tutorial... but for now I find it a bit overwhelming... to much info at once ).

    Greetings
    Robert

    demo.zip

  2. #2
    My tutorial was based on this article: http://www.gamedev.net/page/resource...avity-faq-r694
    It's quite easy to follow.
    NB: The part after 'The REAL Equations' is not mandatory to get it to work and can be skipped it you want.

  3. #3
    Maybe simply like this?

    Code:
    procedure TBlurp.DoMove(TimeGap: Double);
    begin
      inherited;
      if not isfalling then begin
        X:=X+X_direction;
        if X <= 0 then X:=0;
        if X > 640-Image.Width then X:=640-Image.Width;
        if Y < 0 then Y:=0;
        if Y > 480-Image.Height then Y:=480-Image.Height;
      end;
      Collision;
    end;
    but now that I think about it , this problem might go away if I finish up the part where I can't enter a platform from any angle
    That may be true.

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