# NaaLaa

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Air fighter 1945 in a very very simplified version

The main structure of code is divided in two sections :

1. Initialization

2. Main Program (Looping)
Draw the plane
Define keys : Esc to quit, Left and Right to move the plane
Draw enemies
Bullet is auto shoot

Still have miss lots of features   ... somebody please add some code to detect collision between a bullet and an enemy, I am running out of idea on how to code collision detect

Code:
```'INITIALIZATION set window "1945 Simplified", 640, 480 load image 1,"data/plane.png" load image 2,"data/bullet.png" load image 3,"data/enemy.png" load image 4,"data/black.png" speed=4 planeX=640/2        ; planeY=400 bulletX = planeX+15 ; bulletY = planeY enemyX = []         ; enemyY = [] enemyX[0] = 40      ; enemyY[0] = -10 enemyX[1] = 300     ; enemyY[1] = -50 enemyX[2] = 400     ; enemyY[2] = -30 'MAIN PROGRAM do     'SET BACKGROUND      cls      draw image 4,0,0      'THE PLANE      draw image 1,planeX,planeY                             'ESC TO QUIT, LEFT AND RIGHT KEYS TO MOVE THE PLANE      if keydown(KEY_ESCAPE) then end      if keydown(KEY_LEFT)   then planeX=planeX-speed      if keydown(KEY_RIGHT)  then planeX=planeX+speed      'ENEMIES      for x=0 to 2         if enemyY[x]>480 then             enemyX[x]=rnd(640)             enemyY[x]=-rnd(50)          else             enemyY[x]=enemyY[x]+speed          endif       next       for x=0 to 2         draw image 3,enemyX[x],enemyY[x]       next                  'BULLET, AUTO SHOOT          if bulletY < 480 then         bulletY   =   bulletY - speed*3       endif             if bulletY = 100 then         bulletX = planeX+15         bulletY = planeY       endif                                                 draw image 2,bulletX,bulletY      'WAIT BEFORE LOOPING       wait 40 loop```
(11-28-2023, 09:17 AM)1micha.elok Wrote: [ -> ]Air fighter 1945 in a very very simplified version

The main structure of code is divided in two sections :

1. Initialization

2. Main Program (Looping)
Draw the plane
Define keys : Esc to quit, Left and Right to move the plane
Draw enemies
Bullet is auto shoot

Still have miss lots of features   ... somebody please add some code to detect collision between a bullet and an enemy, I am running out of idea on how to code collision detect

Code:
```'INITIALIZATION set window "1945 Simplified", 640, 480 load image 1,"data/plane.png" load image 2,"data/bullet.png" load image 3,"data/enemy.png" load image 4,"data/black.png" speed=4 planeX=640/2        ; planeY=400 bulletX = planeX+15 ; bulletY = planeY enemyX = []         ; enemyY = [] enemyX[0] = 40      ; enemyY[0] = -10 enemyX[1] = 300     ; enemyY[1] = -50 enemyX[2] = 400     ; enemyY[2] = -30 'MAIN PROGRAM do     'SET BACKGROUND      cls      draw image 4,0,0      'THE PLANE      draw image 1,planeX,planeY                             'ESC TO QUIT, LEFT AND RIGHT KEYS TO MOVE THE PLANE      if keydown(KEY_ESCAPE) then end      if keydown(KEY_LEFT)   then planeX=planeX-speed      if keydown(KEY_RIGHT)  then planeX=planeX+speed      'ENEMIES      for x=0 to 2         if enemyY[x]>480 then             enemyX[x]=rnd(640)             enemyY[x]=-rnd(50)          else             enemyY[x]=enemyY[x]+speed          endif       next       for x=0 to 2         draw image 3,enemyX[x],enemyY[x]       next                  'BULLET, AUTO SHOOT          if bulletY < 480 then         bulletY   =   bulletY - speed*3       endif             if bulletY = 100 then         bulletX = planeX+15         bulletY = planeY       endif                                                 draw image 2,bulletX,bulletY      'WAIT BEFORE LOOPING       wait 40 loop```

Looking good!

But may I suggest that you add 'set redraw off' on the line after 'set window' and 'redraw' before 'wait 40'?

Naalaa has a hidden image (a back buffer) the same size as the window. When you draw something (an image, a line of text or anything) it is drawn on the hidden image. If you haven't called 'set redraw off', every time you draw something the entire hidden image is copied to the window. If you have called 'set redraw off', the hidden image is only copied to the window when you manually call 'redraw'. This is much faster and removes "flickering" graphics.
Regarding collision, "just" check if two images overlap. It's easier to understand if you draw some on a paper

Code:
```for x=0 to 2         dead = bulletX + width(2) > enemyX[x] and bulletX < enemyX[x] + width(3) and             bulletY + height(2) > enemyY[x] and bulletY < enemyY[x] + height(3)         if enemyY[x]>480 or dead then             enemyX[x]=rnd(640)             enemyY[x]=-rnd(50)          else             enemyY[x]=enemyY[x]+speed          endif       next```
Oh man. This game brings back memories... 1945. Classic.

If memory serves correctly, I may have the Naalaa5 version, floating around on a drive somewhere. If I can find it, you can use it for reference or even convert it to Naalaa7... Either way I will look forward to playing your game. Classic.
(11-28-2023, 06:17 PM)Marcus Wrote: [ -> ]Regarding collision, "just" check if two images overlap. It's easier to understand if you draw some on a paper
...

Your collision detection code is wonderful, it works like magic.
Now when a bullet hits an enemy, the enemy disappeares

Thanks also for your advice to avoid flickering graphics by 'set redraw off' and 'redraw'

Code:
```'------ revised code to reflect some improvements ------- 'INITIALIZATION set window "1945 Simplified", 640, 480 set redraw off 'faster, removes flickering graphics load image 1,"data_1945/plane.png" load image 2,"data_1945/bullet.png" load image 3,"data_1945/enemy.png" load image 4,"data_1945/black.png" speed=4 planeX=640/2        ; planeY=400 bulletX = planeX+15 ; bulletY = planeY enemyX = []         ; enemyY = [] enemyX[0] = 40      ; enemyY[0] = -10 enemyX[1] = 300     ; enemyY[1] = -50 enemyX[2] = 400     ; enemyY[2] = -30 'MAIN PROGRAM do     'SET BACKGROUND      cls      draw image 4,0,0      'THE PLANE      draw image 1,planeX,planeY                             'ESC TO QUIT, LEFT AND RIGHT KEYS TO MOVE THE PLANE      if keydown(KEY_ESCAPE) then end      if keydown(KEY_LEFT)   then planeX=planeX-speed      if keydown(KEY_RIGHT)  then planeX=planeX+speed      'ENEMIES      for x=0 to 2         'collision detection if bullet and enemy image overlap         dead = bulletX + width(2) > enemyX[x] and bulletX < enemyX[x] + width(3) and             bulletY + height(2) > enemyY[x] and bulletY < enemyY[x] + height(3)         if enemyY[x]>480 or dead then             enemyX[x]=rnd(640)             enemyY[x]=-rnd(50)          else             enemyY[x]=enemyY[x]+speed          endif       next       for x=0 to 2         draw image 3,enemyX[x],enemyY[x]       next                  'BULLET, AUTO SHOOT          if bulletY < 480 then         bulletY   =   bulletY - speed*3       endif             if bulletY = 100 then         bulletX = planeX+15         bulletY = planeY       endif                                                  draw image 2,bulletX,bulletY      'WAIT BEFORE LOOPING       redraw 'faster, removes flickering graphics       wait 40 loop```
(11-29-2023, 03:49 AM)1micha.elok Wrote: [ -> ]
(11-28-2023, 06:17 PM)Marcus Wrote: [ -> ]Regarding collision, "just" check if two images overlap. It's easier to understand if you draw some on a paper
...

Your collision detection code is wonderful, it works like magic.
Now when a bullet hits an enemy, the enemy disappeares

Thanks also for your advice to avoid flickering graphics by 'set redraw off' and 'redraw'

Code:
```'------ revised code to reflect some improvements ------- 'INITIALIZATION set window "1945 Simplified", 640, 480 set redraw off 'faster, removes flickering graphics load image 1,"data_1945/plane.png" load image 2,"data_1945/bullet.png" load image 3,"data_1945/enemy.png" load image 4,"data_1945/black.png" speed=4 planeX=640/2        ; planeY=400 bulletX = planeX+15 ; bulletY = planeY enemyX = []         ; enemyY = [] enemyX[0] = 40      ; enemyY[0] = -10 enemyX[1] = 300     ; enemyY[1] = -50 enemyX[2] = 400     ; enemyY[2] = -30 'MAIN PROGRAM do     'SET BACKGROUND      cls      draw image 4,0,0      'THE PLANE      draw image 1,planeX,planeY                             'ESC TO QUIT, LEFT AND RIGHT KEYS TO MOVE THE PLANE      if keydown(KEY_ESCAPE) then end      if keydown(KEY_LEFT)   then planeX=planeX-speed      if keydown(KEY_RIGHT)  then planeX=planeX+speed      'ENEMIES      for x=0 to 2         'collision detection if bullet and enemy image overlap         dead = bulletX + width(2) > enemyX[x] and bulletX < enemyX[x] + width(3) and             bulletY + height(2) > enemyY[x] and bulletY < enemyY[x] + height(3)         if enemyY[x]>480 or dead then             enemyX[x]=rnd(640)             enemyY[x]=-rnd(50)          else             enemyY[x]=enemyY[x]+speed          endif       next       for x=0 to 2         draw image 3,enemyX[x],enemyY[x]       next                  'BULLET, AUTO SHOOT          if bulletY < 480 then         bulletY   =   bulletY - speed*3       endif             if bulletY = 100 then         bulletX = planeX+15         bulletY = planeY       endif                                                 draw image 2,bulletX,bulletY      'WAIT BEFORE LOOPING       redraw 'faster, removes flickering graphics       wait 40 loop```

No problems! I've added two more versions of your program, but you can ignore them for now if they seem confusing

In 1945_2.n7 I've replaced your two arrays, enemyX and enemyY, with a 2D array, so that the x value of enemy n is in enemy[n][0] and the y value is in enemy[n][1].

1945_3.n7 is a modification of 1945_2.n7, but instead of using enemy[n][0] and enemy[n][1] for position, I use enemy[n].x and enemy[n].y, which makes it easier to read the code.

The . (dot) notation, as in enemy[n].x, really isn't a complicated thing. In n7 you can use both numbers and strings as "keys" to tables. An array is what I call a table where only numeric keys (indexes) are used.

This is an array:

Code:
```hello = [] hello[0] = 13 hello[1] = 12 pln "1: " + hello[1]```

But you can also do this:

Code:
```hello = [] hello["what"] = 13 hello["weird"] = 14 pln "weird: " + hello["weird"]```

And the above is the exact same thing as:

Code:
```hello = [] hello.what = 13 hello.weird = 14 pln "weird: " + hello.weird```

I hope I'm not confusing you or anone else.
(11-29-2023, 06:01 PM)Marcus Wrote: [ -> ]...
The . (dot) notation, as in enemy[n].x, really isn't a complicated thing. In n7 you can use both numbers and strings as "keys" to tables. An array is what I call a table where only numeric keys (indexes) are used.
...

Thank you for sharing the .(dot) notation ...
It improves the readibility of the source code...
I tried to use it and it worked well
I love NAALAA