Contributor: SCOTT TUNSTALL
{
========================================================
EARTH INVADERS (Original LCD game by CGL 1982..)
(I feel a copyright wangle coming on - NOT!)
--------------------------------------------------------
PC CONVERSION EXCLUSIVELY FOR SWAG, BY SCOTT TUNSTALL 1996
(But why? ;) )
Reqs: Turbo Pascal 5.5 +
CGA
Good technique in chatting up women
==========
DISCLAIMER
----------
I (Scott Tunstall) am not responsible if this program causes any
damage to ANY hardware or software part of the computer system it
runs on or detriment to mental health caused (finding any bugs I
may have missed) OK?.
You can alter/delete or even ADD (if you're sad enough) new bits
to the program just as long as I am credited with the ORIGINAL
version. You are not permitted to distribute the original or
changed code for monetary gain however.
========
FORENOTE
--------
I was playing a hand held LCD game one saturday and it was actually
simple to play, yet quite addictive. Unusual for a hand held.
Anyway, being the sad idiot that I am, I decided to convert it to
Pascal, and give y' all a taste of the game. Hope you enjoy playing
it, I certainly almost did ! (in between debugging)
========
THE GAME
--------
Aliens appear on the screen, you must dig holes for them to fall in.
If an alien falls in you must bury it in the hole, but beware! If
an alien touches an alien in a hole it is helped out and will jump
at the human!!!
Maybe, I will write a two player version of this game. After the Bsc,
perhaps?.
Keys are (until I write a define key routine)
CTRL = Dig hole
ALT = Fill hole in (to kill an alien you do this)
CURSOR UP = Move up
CURSOR DOWN = Move down
CURSOR LEFT = Move left
CURSOR RIGHT = Move right
Err... your guy is represented by a 'x' and the aliens are all 's (until
I actually draw up some GFX! (Knowing me - NEVER!).
Hell, what do you want from me, SVGA? ;^)
=============
FOR YOU TO DO
-------------
Add a title screen
Better sound (even samples)
Check if all aliens are dead
2/3/4 player mode
A lager drinking section.... (please! I've always wanted to see a game
with this in it!)
=====
NOTES
-----
NewKbdInt (The Multiple key reader) is appended to the bottom of
this source so it can be compiled. I didn't write it - Lou Duchez
did. Credits to him....
}
uses crt, nwkbdint; { Present in the SWAG }
{
All objects are mapped directly to the map,
no external data types are used to contain Aliens X,Y coordinates
0 = Empty
1 = Wall
2 = Human
3 = Quarter Dug Hole 1
4 = Half Dug Hole 2
5 = Three Quarter Dug Hole 3
6 = Fully Dug Hole
20..40 = Alien (In various stages of falling.. 40 = Not inhole)
}
const Empty = 0;
Wall = 1;
Human = 2;
QuarterDugHole = 3;
HalfDugHole = 4;
ThreeQuarterDugHole = 5;
FullyDugHole = 6;
AlienFilledIn = 19;
AlienCompletelyBuried = 30;
AlienBeginsClimbOut = 36;
AlienAlmostBuried = 40;
AlienHalfBuried = 50;
NormalAlien = 70;
AlienTripped = NormalAlien-5;
Amateur = 1;
Pro = 2;
Kamikaze = 3; { Not implemented, Pro is hard enough! }
UpKey = 72;
DownKey = 80;
LeftKey = 75;
RightKey = 77;
DigKey = 29;
FillKey = 56;
var map : array[1..7,1..5] of byte; { Playfield }
killedplayer : boolean;
SkillLevel : byte;
GameLevel : byte;
GameSpeed : byte;
AlienPause : byte;
HumanX, HumanY : byte;
Currx,Curry : byte;
type AlienInfo = record
AlienState : byte;
AlienX, AlienY : byte;
end;
{
The following values are written to the map, the values contained
may be:
0 = Empty
1 = Wall
2 = Human
3 = Quarter Dug Hole 1
4 = Half Dug Hole 2
5 = Three Quarter Dug Hole 3
6 = Fully Dug Hole
20 + = Reserved for aliens, see constants above
Therefore, if map[1,1] was 3 then that means a Quarter Dug hole
is at the top left of the map.
}
procedure initmap;
var x:byte;
y:byte;
begin
{
Erase all of map. If you're sad enough, like me, then you
could design small maps, or even extend 'em to fill the
entire screen.
}
for y:=1 to 5 do
for x:=1 to 7 do
map[x,y]:=empty;
{
Set Walls
}
for x:=1 to 3 do
begin
map[x *2,2]:=Wall;
map[x *2,4]:=Wall;
end;
{
Determine game speed
}
case SkillLevel of
Amateur : GameSpeed:=6;
Pro : GameSpeed:=2; { Life expectancy - 3 seconds }
Kamikaze : GameSpeed:=1; { Life expectancy - NIL! }
end;
AlienPause:=GameSpeed;
{
Now place aliens
}
for x:=1 to 3 do
map[x*2,1]:=NormalAlien;
if gamelevel > 1 then
begin
map[2,3]:=NormalAlien;
map[6,3]:=NormalAlien;
end;
if gamelevel > 2 then
map[4,3]:=NormalAlien;
{
Place human
}
HumanX:=4;
HumanY:=5;
map[HumanX,HumanY]:=Human;
end;
{ The following 2 procedures are NOT mine; they were written by
Robert E. Swart and cut and pasted to this routine
I modified these routines for my own use!
}
procedure Lines200;
{ Set 200 scanlines on VGA display }
InLine(
$B8/$01/$00/ { mov AX,$0001 }
$CD/$10/ { int $10 }
$B8/$00/$12/ { mov AX,$1200 }
$B3/$30/ { mov BL,$30 }
$CD/$10); { int $10 }
procedure Font8x16;
{ Set 8x16 VGA-font on VGA display }
InLine(
$B8/$01/$00/ { mov AX,$0001 }
$CD/$10/ { int $10 }
$B8/$14/$11/ { mov AX,$1114 }
$B3/$00/ { mov BL,0 }
$CD/$10); { int $10 }
procedure SetCurPos(newx, newy: byte);
begin
currx:=newx-1; { Conv phys to log }
curry:=newy-1;
end;
{ Faster than using the write command for only one char }
procedure text(TheChar: char; TheColour: byte);
begin
memw[$b800: (curry * 80) + (currx SHL 1)]:=word (ord(TheChar)+(TheColour SHL 8));
end;
{
====================================================================
Draw the game screen.
Note: All of the aliens actually exist on map, they are not simply
sprites overlaid on the map during draw time, so in theory you could
fill the entire map with aliens.... Have fun!
--------------------------------------------------------------------
}
procedure DrawMap;
var x, y : byte;
begin
for y:=1 to 5 do
for x:=1 to 7 do
begin
SetCurPos(x,y);
case map[x,y] of
Empty : text(' ', BLACK);
Wall : text('#', BLUE);
Human : text('x', RED);
AlienCompletelyBuried..
(AlienBeginsClimbOut-1) : text(#1, random(7) OR 1);
AlienBeginsClimbout..
(NormalAlien-1) : text(#1, GREEN);
NormalAlien : text(#2, GREEN);
QuarterDugHole : text('.',LIGHTGRAY);
HalfDugHole,
ThreeQuarterDugHole : text('o', LIGHTGRAY);
FullyDugHole : text('O',LIGHTGRAY);
end;
end;
end;
{
==============================================================
Free an alien that may be trapped at maybex, maybey on the map
--------------------------------------------------------------
}
Procedure ReleaseAlien(maybex, maybey: byte);
var TheObject: byte;
begin
if (maybex > 0) and (maybex < 8) and (maybey > 0) and (maybey < 6) then
begin
theObject:=map[maybex, maybey];
if (theObject> AlienFilledIn) And
(theobject < NormalAlien) Then
map[maybex, maybey]:=NormalAlien;
end;
end;
procedure MoveAliens;
var AlienArray : Array[1..10] of AlienInfo;
x, y, TheObject : byte;
index : byte;
noblank : boolean;
NewDir,
NewXp,
NewYp,
ObjectHit : byte;
begin
dec(AlienPause);
if AlienPause = 0 Then
{ Find all aliens on the map, and remember where they
are so they can be moved later.
}
Begin
AlienPause:=GameSpeed;
index:=1;
For y:=1 to 5 do
For x:=1 to 7 do
begin
TheObject:=map[x,y];
If (TheObject >=AlienCompletelyBuried) And
(TheObject <=NormalAlien) Then
With AlienArray[index] do
Begin
AlienState :=TheObject;
AlienX :=x;
AlienY :=y;
Inc(index);
End;
end;
{ Now that an array of aliens has been built up,
move em out! Also note x is being re-used. }
for x:=(index-1) downto 1 do
With AlienArray[x] do
begin
if AlienState = NormalAlien Then
Begin
{ An alien can free it's trapped brother }
releasealien(AlienX-1,AlienY);
releasealien(AlienX+1,AlienY);
releasealien(AlienX,AlienY-1);
releasealien(AlienX,AlienY+1);
{
=============================
Move alien in a direction
-----------------------------
}
NewDir :=random(5)+1;
NewXp :=AlienX;
NewYp :=AlienY;
case NewDir of
1: if newxp <> 1 then dec(newxp);
2: if newxp <> 7 then inc(newxp);
3: if newyp <> 1 then dec(newyp);
4: if newyp <> 5 then inc(newyp);
5..6: if newyp < humany then { A wee bit of AI :) }
inc(newyp)
else
if newyp > humany then
dec(newyp);
end;
{
}
noblank:=false;
objecthit:=map[newxp,newyp];
case objecthit of
empty : map[newxp, newyp]:=NormalAlien;
human : killedplayer:=true;
QuarterDugHole : map[newxp, newyp]:=AlienTripped;
HalfDugHole : map[newxp, newyp]:=AlienHalfBuried;
ThreeQuarterDugHole : map[newxp, newyp]:=AlienAlmostBuried;
FullyDugHole : map[newxp, newyp]:=AlienCompletelyBuried;
else
noblank:=true;
end;
{
Noblank, when set FALSE means the alien has moved
and the area where the alien was on the map shall be
set empty.
}
if not noblank then
map[AlienX, AlienY]:=Empty;
{ I used this for debugging. I thought it was cos
the SWAG keyboard handler was dodgy, but it wasn't
- my code was !!! }
{ gotoxy(1,24); write (chr (random(128)+32)); }
end
else
If AlienState < NormalAlien Then
Begin
TheObject:=Map[AlienX, AlienY];
Inc(TheObject,1);
If TheObject > NormalAlien Then
TheObject:=NormalAlien;
Map[AlienX,AlienY]:=TheObject;
End;
end;
end;
end;
{
======================
Guess what this does ?
----------------------
}
Procedure DigHole(holex, holey: byte);
var TheObject: byte;
Begin
TheObject:=Map[holex, holey];
If TheObject = Empty Then
Map[HoleX,Holey]:=QuarterDugHole
Else
If (TheObject >= QuarterDugHole)
And (TheObject < FullyDugHole) Then
Begin
Sound(50);
Delay(100);
NoSound;
Inc(Map[HoleX,HoleY]);
End;
End;
{
==============================
FILL IN A HOLE / BURY AN ALIEN
------------------------------
}
Procedure FillHole(holex, holey:byte);
Var TheObject: byte;
Begin
TheObject:=Map[Holex, Holey];
If (TheObject >= QuarterDugHole) And (TheObject <= FullyDugHole) Then
Begin
Sound(20);
Delay(100);
NoSound;
Dec(Map[HoleX, HoleY]);
If Map[HoleX, HoleY] < QuarterDugHole Then
Map[HoleX, HoleY]:=Empty;
End
Else
If (TheObject >=AlienFilledIn) And
(TheObject <= AlienBeginsClimbOut) Then
Begin
Sound(90);
Delay(40);
NoSound;
Dec(Map[HoleX,HoleY],1);
If Map[HoleX,HoleY] <= AlienFilledIn Then
Map[HoleX,HoleY]:=Empty;
End;
End;
{
=======================================
Try and move the human to a new square.
If he walks into an alien though....
---------------------------------------
}
Procedure TryMove(newx, newy: byte);
Var TheObject: byte;
Begin
TheObject:=Map[NewX, NewY];
If TheObject = Empty Then
Begin
Map[HumanX, HumanY]:=Empty;
Map[NewX, NewY]:=Human;
HumanX:=newx;
HumanY:=newy;
End
Else
If TheObject = NormalAlien Then
killedplayer:=true;
End;
{
=====================
MOVE THE HUMAN AROUND
---------------------
}
Procedure MovePlayers;
var currpx, currpy : byte;
digging, burying : boolean;
Begin
currpx:=humanx;
currpy:=humany;
digging:=false;
burying:=false;
if (keydown[DigKey]) then
digging:=true
else
if (keydown[FillKey]) then
burying:=true;
if keydown[UpKey] and (currpy <>1) then
begin
if digging or burying then
begin
if digging then
dighole(currpx, currpy-1)
else
fillhole(currpx, currpy-1);
end
else
trymove(currpx,currpy-1);
end
else
if keydown[DownKey] and (currpy <>5) then
begin
if digging or burying then
begin
if digging then
dighole(currpx, currpy+1)
else
fillhole(currpx, currpy+1);
end
else
trymove(currpx,currpy+1);
end
else
if keydown[LeftKey] and (currpx <>1) then
begin
if digging or burying then
begin
if digging then
dighole(currpx-1, currpy)
else
fillhole(currpx-1, currpy);
end
else
trymove(currpx-1,currpy);
end
else
if keydown[RightKey] and (currpx <>7) then
begin
if digging or burying then
begin
if digging then
dighole(currpx+1, currpy)
else
fillhole(currpx+1, currpy);
end
else
trymove(currpx+1,currpy);
end;
end;
begin
randomize;
skilllevel:=amateur;
gamelevel:=1;
initmap; { Set map up }
Lines200;
Font8x16;
hookkeyboardint;
repeat
drawmap;
movealiens;
moveplayers;
delay(125);
until keydown[1] or killedplayer ;
textmode(CO80);
unhookkeyboardint;
end.
{
If you actually play this game in it's unaltered state.. my commiserations!
Contact address: CG93SAT@IBMRISC.DCT.AC.UK
What I'd like to see more of in the SWAG are humour games... the Amiga
has loads (cos it's a joke machine - just kidding, I own one too)
Remember to write that lager drinking sim now ;) !!!
}