1,000+ Great Games/1_1000 Games.iso/WINGAMES/FGWTET11.ZIP/TETRIS.DOC

Text File | 1995-11-02 | 10.9 KB | 274 lines

                      Fastgraph Tetris for Windows
                      ----------------------------
                             By Diana Gruber

I wrote this program for several reasons. First, I am trying to figure
out how Delphi works. Don't laugh. Delphi is powerful and
non-trivial. There are a lot of undocumented features. Even the
documented ones are sometimes cryptic and non-obvious. I'm making
slow progress.

Second, I wanted to beta-test Fastgraph for Windows. Somebody needs to
keep an eye on Ted and make sure he is writing it right.

Third, I wanted to provide a demo program for our Fastgraph/Delphi
users, so they can get an idea how to write Windows games. This is
perhaps not the most brilliant Windows program ever written, but it's
a start. Very likely, you will find better ways to solve some of the
problems this program addresses. If so, please tell me.

Finally, I was asked to judge a contest sponsored by the x2.ftp.oulu
group.  One of the contest categories is "best tetris". I thought
tackling tetris programming myself would make me a better judge.

So here it is, my version of tetris for Windows. It took me about
three weeks to write the program. My understanding of Windows
programming and Delphi programming has improved considerably, and
hopefully looking at this program will shed some light on the process
for you too.

How to install tetris
---------------------

I didn't write an install program for tetris. I've been meaning to do
that.  All you need to do to run tetris is copy all the files into a
subdirectory.  Then you can run the program from the Windows program
manager or from the Delphi IDE.

Files in the distribution
-------------------------

TETICO.ICO  The tetris icon, for minimizing
TETRIS.DCU  Compiled version of TETRIS.PAS
TETRIS.DFM  Delphi project file
TETRIS.PAS  Pascal source code
TETRIS.SPR  Graphics in RLE format.
WINTET.DPR  Source code for the Delphi project
WINTET.EXE  Executable program
WINTET.OPT  Delphi Options
WINTET.RES  Compiled resource file
EATING.WAV  Sound effect
JAYLENO.WAV Sound effect

How to play tetris
------------------

Launch the game from Delphi, or from the Windows program manager.
When the play field appears, try to line up blocks in such a way as
to fill a horizontal row. When an entire row is filled, it will be
munched by langoliers. Then all the rows above it will move down a
row. Keep doing this until you get to the top of the playfield. At
this point, you lose. Play the game again. Keep doing it. This is
entertaining. Honest, it is.

About the source code
---------------------

The source code is written in Borland's Object Pascal, which is what
Delphi really is, under that fancy shell. It is linked with Fastgraph
for Windows, final beta version.

A form is created, and given a size calculated to be twice the size
of the virtual buffer. More about that in a minute. The form is
called TForm1 and is defined as follows:

  TForm1 = class(TForm)
    Panel1: TPanel;
    Button1: TButton;
    Timer1: TTimer;
    Header1: THeader;
    procedure AppOnActivate(Sender: Tobject);
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure FormPaint(Sender: TObject);
    procedure FormResize(Sender: TObject);
    procedure drop_block(Sender: TObject);
    procedure pause(Sender: TObject);
  end;

Four components are added to a form. These are:

   Panel1: a panel component, completely hidden by the button component.
   This component keeps the other components from constantly changing
   focus. Every time you press an arrow key, the focus would switch from
   the header to the button and back again, causing flickering. The
   panel fixes that.

   Button1: a button component, to allow the user to pause and resume the
   game.

   Timer1: the timer component, which triggers each frame of animation.

   Header1: the header component, which shows the score.

In addition, several functions are added to the form. Some of these
are added automatically through the object inspector. Others must be
created manually.  The automatic ones have the letters "Form" as a
prefix. Here are descriptions of what these procedures do:

   procedure AppOnActivate(Sender: Tobject);

This is a manually created procedure that executes when control
switches from another Windows application to tetris, or in other
words, when tetris becomes the top-level window. It is analogous to
the WM_SETFOCUS Windows message handler. We use it in tetris to
realize the application's logical palette, in case the other
application used a different palette.

   procedure FormCreate(Sender: TObject);

This procedure is called one time when the program begins. It is a
good place to set up the device context, logical palette, and virtual
buffers. We also enable the AppOnActivate procedure. It is analogous
to the WM_CREATE Windows message handler.

   procedure FormDestroy(Sender: TObject);

This procedure is called one time when the program exits. It releases
the virtual buffers and other resources. It is analogous to the
WM_DESTROY Windows message handler.

   procedure FormPaint(Sender: TObject);

This procedure is called whenever any portion of the form needs to be
redrawn.  In Delphi, the invalidate procedure (called in
AppOnActivate) will trigger this. Other things can trigger this
procedure too, such as when another Window overlaps part of the form,
or when the form size changes. It is analogous to the WM_PAINT
Windows message handler.

   procedure FormResize(Sender: TObject);

This procedure is called when the size of the form changes, and also
as part of the form creation. It simply records the form dimensions.
It is analogous to the WM_SIZE Windows message handler.

   procedure drop_block(Sender: TObject);

This function was manually created to handle the tetris animation. It
is triggered at regular intervals by the timer component. Each time
this procedure is called, it is considered a "frame of animation".
Usually it involves a block moving downward by several pictures, and
the virtual buffer is blitted to the form.

   procedure pause(Sender: TObject);

This function was manually created to allow the user to pause the
game, for example when the telephone rings, or when you want to run
another application while running tetris. It is triggered by the
button component.

Several other procedures were added as well. These are called by the
drop_block procedure, and handle some moving and displaying the
blocks, and playing the game.

Size of the frame, virtual buffers, and screen
----------------------------------------------

The virtual buffer must be scaled to fit in the window. The frame
defines the size of the window. If the size difference is a factor of
two, the scaling function does less work and is therefore faster. Of
course, the user can scale the window, and the program will still
work. But for efficiency, the program starts with a nice even
multiple of the window size and the virtual buffer size, as follows:

  Virtual buffer size:             240x200
  Frame size:                      480x400
  Play area:                        80x160

The entire virtual buffer is blitted to the frame during a Windows
paint event. During a timer event, however, when the game is
animating, it is not necessary to blit the entire buffer. Only the
play area is blitted. This is more efficient. I blitted the entire
height of the virtual buffer (200 rows) rather than calculating the
length and scaling. Scaling factors are unpredictable as windows are
resized. A partial blit could cause an undesirable stretching or
jaggy effect.

Palette
-------

I grabbed the palette values from a PCX file and put them in an array.
Then I called fg_mapdacs() to translate the RGB components from the
0-63 range used in DOS to the 0-255 range used in Windows. The
logical palette is created using fg_logpal(), passing it the 236
colors in the palette. This is set up in the FormCreate procedure.
The palette is realized with a call to fg_realize() in FormCreate and
also in AppOnActivate.

Important: remember you can only use 236 colors out of 256 in Windows.
The first 10 and last 10 are reserved for Windows. When designing
bitmaps, etc., try to use the colors not reserved by Windows. That
way, you will have more control over them.

Animation
---------

That little langolier critter is cute, isn't he? He's a simple 256
color bitmap in two frames. He is blitted to the virtual buffer using
fg_drwimage().  The remnants of blocks he leaves behind as he munches
are drawn with single-color bitmaps using fg_drawmap(). The color is
determined by looking at the block before it is erased, with
fg_getpixel(). Then the color is set with fg_setcolor(). This is
simple, and it works well.

Double-buffering is achieved by creating another virtual buffer, just
slightly larger than a row of blocks. This holds the clean copy of
the blocks, so as the langoliers munch they can be moved without
leaving remnants.

About Fastgraph for Windows
---------------------------

Fastgraph for Windows allows you to build great graphics applications
for Windows the same way you do for DOS. Powerful, fast low-level
graphics routines interface with your choice of WinG, DirectDraw or
the Windows API and enable you to create fast, smooth animation under
Windows 3.1 and Windows 95.  Both 16- and 32-bit libraries support
most popular C/C++ compilers, Borland Pascal, and Delphi. Port your
Fastgraph DOS code to Windows with just a few simple modifications.
Graphics techniques are extensively documented in a comprehensive
600-page manual. Virtual buffers, bitmaps, file formats, color
palette management, graphics primitives, scaling, blitting, animation,
double and triple buffering, and printing are all supported in a
simple, intuitive, well-documented manner. Writing games for Windows
doesn't get much easier than this! Fastgraph for Windows is only
$249, with no royalties.

Contact information for Fastgraph products
------------------------------------------

Ted Gruber Software
P.O. Box 13408
Las Vegas, NV 89112
[phone] (voice)
[phone] (fax)
[phone] (bbs)

orders only: 1-800-410-0192 (The Coriolis Group)

email:
[e-mail]
[e-mail]

Our ftp site for demos, shareware versions, updates, and lots of games
written with Fastgraph is:

ftp.accessnv.com
  or
http://www.accessnv.com/fastgraph/

Please contact us if you want more information about Fastgraph,
including the current brochure, demo disk and order form.

Other Credits
-------------

Big thanks to Tim Feldman for explaining how to play WAV files in his
article in the Aug/Sep 1995 issue of PC Techniques. the sndPlaySound
function is a great example of a useful but completely undocumented
feature. Way to go, Borland! (Not!)

Thanks, Tim! Also thanks to Tom Repstad and Steve Blackwood for
programming help.