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Im makeing a 2d shootemup game and i was wondering how i can get the enemies to come on the screen and move without them doing the same thing every time.

thanks

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oooPSYooo

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Posted: 23rd Mar 2004 04:18

hum...

1. random pop up positions on screen, e.g.
x=rnd(1000):y=rnd(700)
paste image 33,x,y

2. enemies start to move (random direction), e.g.
direction(enemyx)=rnd(3)+1
do
select direction(enemiex)
case 1: paste image 33,x-3,y:endcase rem left
case 2: paste image 33,x,y-3:endcase rem up
case 3: paste image 33,x+3,y:endcase rem right
case 4: paste image 33,x,y+3:endcase rem down
endselect
...
...
...
loop

3. random direction changes, e.g.
x=rnd(5000)
if x=333 then change_direction(enemyx)

cu,
psy

p.s. dont forget to do a randomize timer() at the beginning of your code

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walaber

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Posted: 23rd Mar 2004 04:45 Edited at: 23rd Mar 2004 04:46

are you using DBPro? if so, TYPES are your friend here!

TYPE Enemy
   x as integer
   y as integer
ENDTYPE

#constant ENEMY_ALIVE 1
#constant ENEMY_DEAD 2


rem THIS PART INITIALIZES ALL OF THE ENEMIES, ADJUST FOR YOU OWN LIKING.

dim Enemies(10) as ENEMY

for i=1 to 10
   Enemies(i).x = rnd(640)
   Enemies(i).y = rnd(480)
next i



rem NOW IN THE GAME LOOP:

do

   rem UPDATE ENEMY POSITIONS!!!
   for i=1 to 10
      Enemies(i).x = Enemies(i).x - 1
      if Enemies(i).x <= 0
         rem RESET POSITION
         Enemies(i).x = 640
         Enemies(i).y = rnd(480)
      endif
   next i

   rem DRAW THE ENEMIES
   for i=1 to 10
      rem draw code here! for example past a sprite to Enemies(i).x,Enemies(i).y
   next i

   sync
loop

...something like that might get you started... if you are already using Types, then just ignore this!! also, if you implement some of the stuff in the above post, you'll get nice random movement!

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zircher

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Posted: 23rd Mar 2004 21:47

Another trick it to create random goals and not random movement. When an enemy spawns/respawns, set a random location for them to move to. That way they'll avoid the drunkard's walk of random movement.

To make random goals work, you need to decide on how fast an enemy is and how many 'steps' it will take to get there. Let's say that an enemy always takes 100 steps to reach a goal. If the enemy starts at 0,0 and the random goal is +125,-200, the enemy would only need to move +1.25,-2.0 every loop to reach the goal in 100 steps.

A more sophisticated method would be to make that system timer based and not frame rate based. But, that's another post, if desired. Of course, not all enemy units move in a straight line either. So, advanced units might move in a pattern towards a goal and some units might be able to detect a player and either change course when within a set range or perhaps change their goal to intercept the player.
--
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AJay

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Posted: 23rd Mar 2004 22:34

could you give me some example code Zircher

Thanks to all for your help

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UnderLord

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Posted: 23rd Mar 2004 23:35

its easy just set up a random movement if you have movement code for the AI right now then modify it for random movement using rnd() command

The search continues.

Current project - A space game

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zircher

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Posted: 24th Mar 2004 00:05 Edited at: 24th Mar 2004 00:07

Quote: "could you give me some example code Zircher"

Not yet since I know nothing about your game setup, how you define enemy units, their entry and exit points, how they are stored (arrays and UDTs), etc.

It's not hard to do, but I'd be basically writing the in dark code that would be useless at this moment.

Do you have some code that I can modify or have you not gotten past the design stage yet?

If you're still in the design stage, I strongly suggest creating a user defined type that contains your enemy data. Include fields such as ID number, enemy type, current location X & Y, goal X & Y, and perhaps an IsDead flag and a Respawn flag. All that data can later be used to control your enemy units in a loop so they appear to be all moving at the same time when you SYNC the screen.
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walaber

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Posted: 24th Mar 2004 04:57

Zircher's idea (as usual) has some sauce!

in basic terms, you'd do something like this:

TYPE 2dPoint
   x as integer
   y as integer
ENDTYPE

TYPE Enemy
   Pos as 2dPoint
   Goal as 2dPoint

Step as 2dPoint
   rem OTHER STUFF HERE
ENDTYPE

rem MAKE THE ARRAY
dim Enemies(15) as ENEMY

rem Simple Init Code, change to your liking
function InitEnemies(num as integer)
   rem RANDOM START POSITION
   Enemies(num).Pos.x = rnd(640)
   Enemies(num).Pos.y = rnd(480)

rem RANDOM GOAL POSITION
   Enemies(num).Goal.x = rnd(640)
   Enemies(num).Goal.y = rnd(480)

rem How far to move each loop
   Enemies(num).Step.x = (Enemies(num).Goal.x - Enemies(num).Pos.x) / 15
   Enemies(num).Step.y = (Enemies(num).Goal.y - Enemies(num).Pos.y) / 15

rem OTHER INIT CODE HERE IF YOU NEED IT
endfunction

rem MOVE AN ENEMY!
function MoveEnemy(num as integer)
   inc Enemies(num).Pos.x, Enemies(num).Step.x
   inc Enemies(num).Pos.y, Enemies(num).Step.y
endfunction

rem BASIC ENEMY LOOP
   for i=1 to 15
      MoveEnemy(i)

DrawEnemy(i) : rem MAKE THIS COMMAND YOURSELF BASED ON POS.x POS.y

next i
endfunction

TYPE 2dPoint
   x as integer
   y as integer
ENDTYPE

TYPE Enemy
   Pos as 2dPoint
   Goal as 2dPoint

   Step as 2dPoint
   rem OTHER STUFF HERE
ENDTYPE

rem MAKE THE ARRAY
dim Enemies(15) as ENEMY


rem Simple Init Code, change to your liking
function InitEnemies(num as integer)
   rem RANDOM START POSITION
   Enemies(num).Pos.x = rnd(640)
   Enemies(num).Pos.y = rnd(480)

   rem RANDOM GOAL POSITION
   Enemies(num).Goal.x = rnd(640)
   Enemies(num).Goal.y = rnd(480)

   rem How far to move each loop
   Enemies(num).Step.x = (Enemies(num).Goal.x - Enemies(num).Pos.x) / 15
   Enemies(num).Step.y = (Enemies(num).Goal.y - Enemies(num).Pos.y) / 15

   rem OTHER INIT CODE HERE IF YOU NEED IT
endfunction


rem MOVE AN ENEMY!
function MoveEnemy(num as integer)
   inc Enemies(num).Pos.x, Enemies(num).Step.x
   inc Enemies(num).Pos.y, Enemies(num).Step.y
endfunction


rem BASIC ENEMY LOOP
   for i=1 to 15
      MoveEnemy(i)

      DrawEnemy(i) : rem MAKE THIS COMMAND YOURSELF BASED ON POS.x POS.y

   next i
endfunction

this in not complete, but should give you an idea of how you could do it. you could also add a variable for NumOfSteps to each enemy, so they don't all reach their goal at the same time, etc etc etc

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zircher

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Posted: 24th Mar 2004 16:59 Edited at: 24th Mar 2004 17:07

Walaber is on the money, but I want to take the time and reorganize his code to avoid some problems with function declarations...

rem  Note this code fragment does not include enemy creation and
rem  display.  This code can be used with sprites, plain objects,
rem  or 3d models since the code is independent of object type.

TYPE 2dPoint
   x as integer
   y as integer
ENDTYPE

TYPE Enemy
   Pos as 2dPoint
   Goal as 2dPoint

Step as 2dPoint
   rem OTHER STUFF HERE
ENDTYPE

rem MAKE THE ARRAY
dim Enemies(15) as ENEMY
for a 1 to 15: InitEnemies(a): next a

rem main game loop
do
  rem BASIC ENEMY LOOP
  for i=1 to 15
    MoveEnemy(i)
    DrawEnemy(i) : rem MAKE THIS COMMAND YOURSELF BASED ON POS.x POS.y
  next i
loop

rem  Always good to include an END statment even if you never
rem  reach it.  All function declarations need to appear at the
rem  end of the program.
end

rem Simple Init Code, change to your liking
function InitEnemies(num as integer)
   rem RANDOM START POSITION
   Enemies(num).Pos.x = rnd(640)
   Enemies(num).Pos.y = rnd(480)

rem RANDOM GOAL POSITION
   Enemies(num).Goal.x = rnd(640)
   Enemies(num).Goal.y = rnd(480)

rem How far to move each loop
   Enemies(num).Step.x = (Enemies(num).Goal.x - Enemies(num).Pos.x) / 15
   Enemies(num).Step.y = (Enemies(num).Goal.y - Enemies(num).Pos.y) / 15

rem OTHER INIT CODE HERE IF YOU NEED IT
endfunction

rem MOVE AN ENEMY!
function MoveEnemy(num as integer)
   inc Enemies(num).Pos.x, Enemies(num).Step.x
   inc Enemies(num).Pos.y, Enemies(num).Step.y
   rem add collision checks here and update flags
endfunction

rem DRAW AN ENEMY!
function DrawEnemy(num as integer)
   rem display/position/animation code goes here
endfunction

rem  Note this code fragment does not include enemy creation and
rem  display.  This code can be used with sprites, plain objects,
rem  or 3d models since the code is independent of object type.

TYPE 2dPoint
   x as integer
   y as integer
ENDTYPE

TYPE Enemy
   Pos as 2dPoint
   Goal as 2dPoint

   Step as 2dPoint
   rem OTHER STUFF HERE
ENDTYPE

rem MAKE THE ARRAY
dim Enemies(15) as ENEMY
for a 1 to 15: InitEnemies(a): next a

rem main game loop
do
  rem BASIC ENEMY LOOP
  for i=1 to 15
    MoveEnemy(i)
    DrawEnemy(i) : rem MAKE THIS COMMAND YOURSELF BASED ON POS.x POS.y
  next i
loop

rem  Always good to include an END statment even if you never
rem  reach it.  All function declarations need to appear at the
rem  end of the program.
end

rem Simple Init Code, change to your liking
function InitEnemies(num as integer)
   rem RANDOM START POSITION
   Enemies(num).Pos.x = rnd(640)
   Enemies(num).Pos.y = rnd(480)

   rem RANDOM GOAL POSITION
   Enemies(num).Goal.x = rnd(640)
   Enemies(num).Goal.y = rnd(480)

   rem How far to move each loop
   Enemies(num).Step.x = (Enemies(num).Goal.x - Enemies(num).Pos.x) / 15
   Enemies(num).Step.y = (Enemies(num).Goal.y - Enemies(num).Pos.y) / 15

   rem OTHER INIT CODE HERE IF YOU NEED IT
endfunction


rem MOVE AN ENEMY!
function MoveEnemy(num as integer)
   inc Enemies(num).Pos.x, Enemies(num).Step.x
   inc Enemies(num).Pos.y, Enemies(num).Step.y
   rem add collision checks here and update flags
endfunction

rem DRAW AN ENEMY!
function DrawEnemy(num as integer)
   rem display/position/animation code goes here
endfunction

Just an extra comment here. Walaber uses deltaX/15 and deltaY/15 to determine the step size. This will make units travel at different speeds depending on the distance between start and goal positions. If you want a constant speed, you can use a fixed step size. Pros and cons to each method.
--
TAZ

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AJay

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Posted: 24th Mar 2004 17:05 Edited at: 24th Mar 2004 17:07

Ill take a look at that code and see if i can make heads or tails out of it.
Here is the code for what i have of my game right now. The starts on the screen and when you shoot it, it just disappears.

Rem Sets up Sync rate and hides mouse
Sync on
Sync Rate 40
Hide Mouse

Rem Loads Media For Game
Load Image "stars.bmp", 1
Load Image "schiff.jpg", 2
Load Image "greenlazer.jpg", 3
Load Image "enemy1.jpg", 4
Load sound "phaser03.wav", 1

Rem Variables
pf = 0
ysx = 50
ysy = 200
shoot = 0
esx = 400
esy = 150

Rem Creates The background and Positions it
Make Object Plain 1, 600, 100
Position Object 1, 0, -4, 70

Rem Textures the background object and locks it on screen
Texture Object 1, 1
Lock Object on 1

Rem places ship on screen
Sprite 1, ysx, ysy, 2

Rem Places First Enemy Ship on screen
Sprite 3, esx, esy, 4

Rem Main Loop
Do
   Rem refreshes sprite
   Sprite 1, ysx, ysy, 2

Rem Goes to scroll back subroutine
   Gosub scrollback:

Rem Goes to moveup subroutine
   Gosub moveup:

Rem Goes to movedown subroutine
   Gosub movedown:

Rem Goes to moveforward subroutine
   Gosub moveforward:

Rem Goes to moveback subroutine
   Gosub moveback:

Rem Goes to shoot subroutine
   Gosub shoot:

Rem Goes to explode subroutine
   Gosub explode:
   Sync
Loop

Rem Scrolls the star background
scrollback:
Scroll Object Texture 1, 0.008, 0.0
Return

Rem Moves ship up if Up key is pressed
moveup:
If Upkey() = 1 and ysy > 0
   Dec ysy, 10
Endif
Return

Rem Moves ship down if Down key is pressed
movedown:
If Downkey() = 1 and ysy < 430
   Inc  ysy, 10
Endif
Return

Rem Moves ship forward if Right key is pressed
moveforward:
If Rightkey() = 1 and ysx < 150
   Inc ysx, 10
Endif
Return

Rem Moves ship backwards if Left key is pressed
moveback:
If Leftkey() = 1 and ysx > 0
   Dec ysx, 10
Endif
Return

Rem Controls displays laser and shoots
shoot:
Rem Creates Variables for laser
If shoot = 0
   lx = sprite x (1) + 10
   ly = sprite y (1) + 20
Endif
Rem Displays Laser
If Spacekey() = 1 and shoot = 0
   Shoot = 1
   Sprite 2, lx, ly, 3
   play sound 1
Endif
Rem Moves Laser accross screen
If sprite exist(2) = 1
   If Sprite X(2) < 639
      lx = lx + 45
      Sprite 2, lx, ly, 3
   Endif
   IF Sprite X(2) >639
      Delete sprite 2
      Shoot = 0
   Endif
Endif
Return

explode:
If shoot = 1 and sprite exist(2) = 1
   If Sprite Hit(2,3) = 1
      Delete Sprite 3
      Delete Sprite 2
      shoot = 0
   Endif
Endif
Return


Rem Sets up Sync rate and hides mouse
Sync on
Sync Rate 40
Hide Mouse

Rem Loads Media For Game
Load Image "stars.bmp", 1
Load Image "schiff.jpg", 2
Load Image "greenlazer.jpg", 3
Load Image "enemy1.jpg", 4
Load sound "phaser03.wav", 1

Rem Variables
pf = 0
ysx = 50
ysy = 200
shoot = 0
esx = 400
esy = 150


Rem Creates The background and Positions it
Make Object Plain 1, 600, 100
Position Object 1, 0, -4, 70

Rem Textures the background object and locks it on screen
Texture Object 1, 1
Lock Object on 1

Rem places ship on screen
Sprite 1, ysx, ysy, 2

Rem Places First Enemy Ship on screen
Sprite 3, esx, esy, 4




Rem Main Loop
Do
   Rem refreshes sprite
   Sprite 1, ysx, ysy, 2

   Rem Goes to scroll back subroutine
   Gosub scrollback:

   Rem Goes to moveup subroutine
   Gosub moveup:

   Rem Goes to movedown subroutine
   Gosub movedown:

   Rem Goes to moveforward subroutine
   Gosub moveforward:

   Rem Goes to moveback subroutine
   Gosub moveback:

   Rem Goes to shoot subroutine
   Gosub shoot:

   Rem Goes to explode subroutine
   Gosub explode:
   Sync
Loop

Rem Scrolls the star background
scrollback:
Scroll Object Texture 1, 0.008, 0.0
Return

Rem Moves ship up if Up key is pressed
moveup:
If Upkey() = 1 and ysy > 0
   Dec ysy, 10
Endif
Return

Rem Moves ship down if Down key is pressed
movedown:
If Downkey() = 1 and ysy < 430
   Inc  ysy, 10
Endif
Return

Rem Moves ship forward if Right key is pressed
moveforward:
If Rightkey() = 1 and ysx < 150
   Inc ysx, 10
Endif
Return

Rem Moves ship backwards if Left key is pressed
moveback:
If Leftkey() = 1 and ysx > 0
   Dec ysx, 10
Endif
Return

Rem Controls displays laser and shoots
shoot:
Rem Creates Variables for laser
If shoot = 0
   lx = sprite x (1) + 10
   ly = sprite y (1) + 20
Endif
Rem Displays Laser
If Spacekey() = 1 and shoot = 0
   Shoot = 1
   Sprite 2, lx, ly, 3
   play sound 1
Endif
Rem Moves Laser accross screen
If sprite exist(2) = 1
   If Sprite X(2) < 639
      lx = lx + 45
      Sprite 2, lx, ly, 3
   Endif
   IF Sprite X(2) >639
      Delete sprite 2
      Shoot = 0
   Endif
Endif
Return

explode:
If shoot = 1 and sprite exist(2) = 1
   If Sprite Hit(2,3) = 1
      Delete Sprite 3
      Delete Sprite 2
      shoot = 0
   Endif
Endif
Return

This is as far as i have gotten, would your example code work with this.

Thanks alot

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zircher

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Posted: 24th Mar 2004 17:11

Did you want to try and merge Walaber's code before continuing? Also, I noticed that you delete sprites on a hit. It might be better to just move those sprites off screen instead of creating/deleting them all the time.
--
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AJay

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Posted: 24th Mar 2004 17:13

ok, ill change my code to move them off of screen, would that make it run faster?

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AJay

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Posted: 24th Mar 2004 17:15

i would like ot merge his code with mine. But i dont really know how to go about doing that.

AJAy

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zircher

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Posted: 24th Mar 2004 21:01 Edited at: 24th Mar 2004 21:01

Take a look at how I re-arranged it. There is an initialization section, a loop code section, and the functions (usually after the END statement and all the sub routines. Just add the code fragments in one section at a time and make any changes you need to prevent syntax errors (F4). After that, we'll have a good starting point.
--
TAZ

BTW, yes you should gain a little speed by skipping the deletion command.

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walaber

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Posted: 25th Mar 2004 05:21

Zircher - thanks for cleaning up my code, I typed it off the top of my head here at work, and later realized (after looking at your fixes) that it might be confusing for someone to try and implement into a program

if you actually get my code up and running for you, let me know

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Jason

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Posted: 26th Mar 2004 00:09 Edited at: 26th Mar 2004 00:10

Hello, I have also started working on a 2d side scrolling shoot em up, I have come up with the typical enemies, Sine waves, point and head towards you etc. But I am now looking to find a program that will let you plot paths with the mouse and dump the results to a text file or something. I have spent a long time searching the net but with little luck.....it's starting to look like I am going to have to write this program myself.

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zircher

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Posted: 26th Mar 2004 02:30

Well, it wouldn't be that hard to do. One thing to watch out for is button bounce. You would want to add a mouse button delay so you don't have multiple way points every time you click.
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AJay

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Posted: 30th Mar 2004 18:15 Edited at: 30th Mar 2004 18:32

OK, I just got around to trying to put your code into mine and it would not work. Im not even sure if i did it right at all.

Rem Sets up Sync rate and hides mouse
Sync on
Sync Rate 40
Hide Mouse

Rem Loads Media For Game
Load Image "mediastars.bmp", 1
Load Image "mediaship.jpg", 2
Load Image "mediagreenlazer.jpg", 3
Load Image "mediaenemy1.jpg", 4
Load Image "mediashipup.jpg", 5
Load Image "mediashipdown.jpg", 6
Load Image "mediaflame.bmp",7
Load sound "mediaphaser03.wav", 1
Load sound "mediaboom2.wav", 2

Rem Variables
pf = 0
ysx = 50
ysy = 200
shoot = 0
bomb = 0
esx = 400
esy = 150
bleft = 3

Rem Creates The background and Positions it
Make Object Plain 1, 600, 100
Position Object 1, 0, -4, 70

Rem Textures the background object and locks it on screen
Texture Object 1, 1
Lock Object on 1

Rem places ship on screen
Sprite 1, ysx, ysy, 2

Rem Places First Enemy Ship on screen
Sprite 3, esx, esy, 4

TYPE 2dPoint
   x as integer
   y as integer
ENDTYPE

TYPE Enemy
   Pos as 2dPoint
   Goal as 2dPoint

Step as 2dPoint
   rem OTHER STUFF HERE
ENDTYPE

rem MAKE THE ARRAY
dim Enemies(15) as ENEMY
for a 1 to 15: InitEnemies(a): next a

Rem Main Loop
Do

rem BASIC ENEMY LOOP
  for i=1 to 15
    MoveEnemy(i)
    DrawEnemy(i) : rem MAKE THIS COMMAND YOURSELF BASED ON POS.x POS.y
  next i

Rem refreshes sprite
   If Upkey() = 0 And Downkey() = 0
      Sprite 1, ysx, ysy, 2
   Endif

Rem goes to bleft subroutine
   Gosub bleft:

Rem Goes to scroll back subroutine
   Gosub scrollback:

Rem Goes to moveup subroutine
   Gosub moveup:

Rem Goes to movedown subroutine
   Gosub movedown:

Rem Goes to moveforward subroutine
   Gosub moveforward:

Rem Goes to moveback subroutine
   Gosub moveback:

Rem Goes to shoot subroutine
   Gosub shoot:

Rem Goes to bomb subroutine
   Gosub bomb:

Rem Goes to hitlaser subroutine
   Gosub hitlaser:

Rem Goes to hitbomb subroutine
   Gosub hitbomb:
   Sync
Loop

Rem Places and refreshes number of bombs on screen.
bleft:
Ink RGB(255,255,255),RGB(0,0,0)
Center Text 590,450,"Bombs: " + str$(bleft)
INK RGB(0,0,0),RGB(255,255,255)
Return

Rem Scrolls the star background
scrollback:
Scroll Object Texture 1, 0.008, 0.0
Return

Rem Moves ship up if Up key is pressed
moveup:
If Upkey() = 1 and ysy > 0
   Dec ysy, 10
   Sprite 1, ysx, ysy, 5
Endif
Return

Rem Moves ship down if Down key is pressed
movedown:
If Downkey() = 1 and ysy < 430
   Inc  ysy, 10
   Sprite 1, ysx, ysy, 6
Endif
Return

Rem Moves ship forward if Right key is pressed
moveforward:
If Rightkey() = 1 and ysx < 150
   Inc ysx, 10
Endif
Return

Rem Moves ship backwards if Left key is pressed
moveback:
If Leftkey() = 1 and ysx > 0
   Dec ysx, 10
Endif
Return

Rem Controls displays laser and shoots
shoot:
Rem Creates Variables for laser
If shoot = 0
   lx = sprite x (1) + 35
   ly = sprite y (1) + 29
Endif
Rem Displays Laser
If Spacekey() = 1 and shoot = 0
   Shoot = 1
   Sprite 2, lx, ly, 3
   play sound 1
Endif
Rem Moves Laser accross screen
If sprite exist(2) = 1
   If Sprite X(2) < 639
      lx = lx + 45
      Sprite 2, lx, ly, 3
   Endif
   IF Sprite X(2) > 639
      Sprite 2, 700, 480, 3
      Shoot = 0
   Endif
Endif
Return

bomb:
Rem Creates Variables for Bomb
If bomb = 0
   bx = sprite x (1) + 45
   by = sprite y (1) + 5
Endif
Rem Displays Bomb
If shiftkey() = 1 and bomb = 0 and bleft > 0
   bomb = 1
   bleft = bleft - 1
      If bleft < 0
         bleft = 0
      Endif
   sprite 4, bx, by, 7
Endif
Rem Moves bomb across screen
If Sprite exist(4) = 1
   If sprite X(4) < 639
      bx = bx + 35
      sprite 4, bx, by, 7
   Endif
   If Sprite X(4) > 639
      Sprite 4, 700, 480,7
      bomb = 0
   Endif
Endif
Return

hitlaser:
If shoot = 1 and sprite exist(2) = 1
   If Sprite Hit(2,3) = 1
      Sprite 2, 700,480, 3
      Sprite 3, 700, 480, 4
      shoot = 0
      Play Sound 2
   Endif
Endif
Return

hitbomb:
If bomb = 1 and sprite exist (4) = 1
   If Sprite Hit (4,3) = 1
      Sprite 4, 700, 480,7
      Sprite 3, 700, 480,4
      bomb = 0
   Endif
Endif
Return
end

rem  Always good to include an END statment even if you never
rem  reach it.  All function declarations need to appear at the
rem  end of the program.

rem Simple Init Code, change to your liking
function InitEnemies(num as integer)
   rem RANDOM START POSITION
   Enemies(num).Pos.x = rnd(640)
   Enemies(num).Pos.y = rnd(480)

rem RANDOM GOAL POSITION
   Enemies(num).Goal.x = rnd(640)
   Enemies(num).Goal.y = rnd(480)

rem How far to move each loop
   Enemies(num).Step.x = (Enemies(num).Goal.x - Enemies(num).Pos.x) / 15
   Enemies(num).Step.y = (Enemies(num).Goal.y - Enemies(num).Pos.y) / 15

rem OTHER INIT CODE HERE IF YOU NEED IT
endfunction

rem MOVE AN ENEMY!
function MoveEnemy(num as integer)
   inc Enemies(num).Pos.x, Enemies(num).Step.x
   inc Enemies(num).Pos.y, Enemies(num).Step.y
   rem add collision checks here and update flags
endfunction

rem DRAW AN ENEMY!
function DrawEnemy(num as integer)
   rem display/position/animation code goes here
endfunction

Rem Sets up Sync rate and hides mouse
Sync on
Sync Rate 40
Hide Mouse

Rem Loads Media For Game
Load Image "mediastars.bmp", 1
Load Image "mediaship.jpg", 2
Load Image "mediagreenlazer.jpg", 3
Load Image "mediaenemy1.jpg", 4
Load Image "mediashipup.jpg", 5
Load Image "mediashipdown.jpg", 6
Load Image "mediaflame.bmp",7
Load sound "mediaphaser03.wav", 1
Load sound "mediaboom2.wav", 2


Rem Variables
pf = 0
ysx = 50
ysy = 200
shoot = 0
bomb = 0
esx = 400
esy = 150
bleft = 3


Rem Creates The background and Positions it
Make Object Plain 1, 600, 100
Position Object 1, 0, -4, 70

Rem Textures the background object and locks it on screen
Texture Object 1, 1
Lock Object on 1

Rem places ship on screen
Sprite 1, ysx, ysy, 2

Rem Places First Enemy Ship on screen
Sprite 3, esx, esy, 4



TYPE 2dPoint
   x as integer
   y as integer
ENDTYPE

TYPE Enemy
   Pos as 2dPoint
   Goal as 2dPoint

   Step as 2dPoint
   rem OTHER STUFF HERE
ENDTYPE


rem MAKE THE ARRAY
dim Enemies(15) as ENEMY
for a 1 to 15: InitEnemies(a): next a






Rem Main Loop
Do

  rem BASIC ENEMY LOOP
  for i=1 to 15
    MoveEnemy(i)
    DrawEnemy(i) : rem MAKE THIS COMMAND YOURSELF BASED ON POS.x POS.y
  next i


   Rem refreshes sprite
   If Upkey() = 0 And Downkey() = 0
      Sprite 1, ysx, ysy, 2
   Endif

   Rem goes to bleft subroutine
   Gosub bleft:

   Rem Goes to scroll back subroutine
   Gosub scrollback:

   Rem Goes to moveup subroutine
   Gosub moveup:

   Rem Goes to movedown subroutine
   Gosub movedown:

   Rem Goes to moveforward subroutine
   Gosub moveforward:

   Rem Goes to moveback subroutine
   Gosub moveback:

   Rem Goes to shoot subroutine
   Gosub shoot:

   Rem Goes to bomb subroutine
   Gosub bomb:

   Rem Goes to hitlaser subroutine
   Gosub hitlaser:

   Rem Goes to hitbomb subroutine
   Gosub hitbomb:
   Sync
Loop

Rem Places and refreshes number of bombs on screen.
bleft:
Ink RGB(255,255,255),RGB(0,0,0)
Center Text 590,450,"Bombs: " + str$(bleft)
INK RGB(0,0,0),RGB(255,255,255)
Return

Rem Scrolls the star background
scrollback:
Scroll Object Texture 1, 0.008, 0.0
Return

Rem Moves ship up if Up key is pressed
moveup:
If Upkey() = 1 and ysy > 0
   Dec ysy, 10
   Sprite 1, ysx, ysy, 5
Endif
Return

Rem Moves ship down if Down key is pressed
movedown:
If Downkey() = 1 and ysy < 430
   Inc  ysy, 10
   Sprite 1, ysx, ysy, 6
Endif
Return

Rem Moves ship forward if Right key is pressed
moveforward:
If Rightkey() = 1 and ysx < 150
   Inc ysx, 10
Endif
Return

Rem Moves ship backwards if Left key is pressed
moveback:
If Leftkey() = 1 and ysx > 0
   Dec ysx, 10
Endif
Return

Rem Controls displays laser and shoots
shoot:
Rem Creates Variables for laser
If shoot = 0
   lx = sprite x (1) + 35
   ly = sprite y (1) + 29
Endif
Rem Displays Laser
If Spacekey() = 1 and shoot = 0
   Shoot = 1
   Sprite 2, lx, ly, 3
   play sound 1
Endif
Rem Moves Laser accross screen
If sprite exist(2) = 1
   If Sprite X(2) < 639
      lx = lx + 45
      Sprite 2, lx, ly, 3
   Endif
   IF Sprite X(2) > 639
      Sprite 2, 700, 480, 3
      Shoot = 0
   Endif
Endif
Return

bomb:
Rem Creates Variables for Bomb
If bomb = 0
   bx = sprite x (1) + 45
   by = sprite y (1) + 5
Endif
Rem Displays Bomb
If shiftkey() = 1 and bomb = 0 and bleft > 0
   bomb = 1
   bleft = bleft - 1
      If bleft < 0
         bleft = 0
      Endif
   sprite 4, bx, by, 7
Endif
Rem Moves bomb across screen
If Sprite exist(4) = 1
   If sprite X(4) < 639
      bx = bx + 35
      sprite 4, bx, by, 7
   Endif
   If Sprite X(4) > 639
      Sprite 4, 700, 480,7
      bomb = 0
   Endif
Endif
Return

hitlaser:
If shoot = 1 and sprite exist(2) = 1
   If Sprite Hit(2,3) = 1
      Sprite 2, 700,480, 3
      Sprite 3, 700, 480, 4
      shoot = 0
      Play Sound 2
   Endif
Endif
Return

hitbomb:
If bomb = 1 and sprite exist (4) = 1
   If Sprite Hit (4,3) = 1
      Sprite 4, 700, 480,7
      Sprite 3, 700, 480,4
      bomb = 0
   Endif
Endif
Return
end

rem  Always good to include an END statment even if you never
rem  reach it.  All function declarations need to appear at the
rem  end of the program.


rem Simple Init Code, change to your liking
function InitEnemies(num as integer)
   rem RANDOM START POSITION
   Enemies(num).Pos.x = rnd(640)
   Enemies(num).Pos.y = rnd(480)

   rem RANDOM GOAL POSITION
   Enemies(num).Goal.x = rnd(640)
   Enemies(num).Goal.y = rnd(480)

   rem How far to move each loop
   Enemies(num).Step.x = (Enemies(num).Goal.x - Enemies(num).Pos.x) / 15
   Enemies(num).Step.y = (Enemies(num).Goal.y - Enemies(num).Pos.y) / 15

   rem OTHER INIT CODE HERE IF YOU NEED IT
endfunction


rem MOVE AN ENEMY!
function MoveEnemy(num as integer)
   inc Enemies(num).Pos.x, Enemies(num).Step.x
   inc Enemies(num).Pos.y, Enemies(num).Step.y
   rem add collision checks here and update flags
endfunction

rem DRAW AN ENEMY!
function DrawEnemy(num as integer)
   rem display/position/animation code goes here
endfunction

When i try to compile it, it says it could not understand for statement at line 61
I know that i probably did this completely wrong.

Im also having trouble with types. What are they and what do they do?
-AJay-
Thanks

P4 3.2GHZ, 256MB DDR Ram, 64MB NVidea G-Force 4, Sound Blaster Live, 40 Gig HD Thanks to Coding Area

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zircher

22

Years of Service

User Offline

Joined: 27th Dec 2002

Location: Oklahoma

Posted: 30th Mar 2004 18:58 Edited at: 30th Mar 2004 18:59

I'll try to look at the code at lunch time.

Types allow you to organize your data in meaningful groups. It also provides for a cleaner design and includes some syntax/error checking for you. [This can be a life saver.]

For example, you can have separate arrays for each of your enemies:

dim enemyX(20)
dim enemyY(20)

For a complex object with many properties, that can get tedious and if you need to change the array size you have to change it everywhere. With types, you declare the type once and the array once. If you need to edit or add fields, you only have to change the type definition and not the array calls.

Types are similar to C structures and are a big step towards better design and code structure.
--
TAZ