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

[robert83]

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...)

 
 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

[Traveler]

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.

[User137]

Maybe simply like this?

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.