Blitz Basic 2 basics

[Nightfox]

Guys I'm wondering how to pass arrays (as pointers) to functions/statements. I have an array that needs to be accessed in a statement without needing to create a new one. I wasn't sure how to do this and my attempts just ended with an error saying the array hadn't been Dimmed although the array works fine outisidr the statement

[Cylon]

You can put a SHARED cmd

inside the Statement, e.g. in the furst line.

Statement foo{}
SHARED mydim()
...
End Statement

All variables can be 'shared', so you can list them one after each other, e.g.

SHARED mydim(), counter.w, *rport.RastPort

This is the common way. Pointers of arrays are possible, too. I would rather not call this 'basics'.

[Havie]

Originally Posted by Daedalus

That should also work with a palette loaded optionally with the LoadShape command. The Use Palette command is only for screens and slices from what I remember, and was replaced with ShowPalette anyway, which would explain why it doesn't work. DisplayPalette is the equivalent for the Display library so that should work fine.

Ok making progress and I can load the paette and use the showpalette. Thanks.

Next question - I'm using a dual playfields (don't really have to but experimenting) and my main character is a sprite. it displays fine and the game is running well but I have no idea how to change the sprite colour! I know the sprites using the top 16 colours of the palette but as I am using dualplayfields if I load a bob with more than 8 colours I get a too many bitplanes error and if I try and use RGB to change a colour I get object not used error. I guess there is a command that allows me to define the palette from within BB2 to control sprite colours or am I barking up the wrong tree?

Thanks.

[Daedalus]

Yes, the sprites use various colour registers depending on the setup, but that number is "translated" from the sprite shape itself. For example, if you're using colours 240-255, colour 0 of the sprite will be entry 240 on the palette object (but will be transparent so moot...), colour 1 on the sprite will be entry 241 etc.

Note that this is on AGA setups only; OCS/ECS-compatible sprite modes use different, lower registers.

[Havie]

Got that. Using only ECS so sprite registers are 16-31 but still having real problems getting the palette to show up. It may be that I am not setting up the screen properly?
Will keep trying - if I can't get it working it may need it's own thread...

[Havie]

Made some good progress finally! In the end I have set up a 32 colour screen and saved a 32 colour palette from Dpaint. This works fine for the sprites and the top 16 colours - yeah! On the other hand bobs (which I am putting on the screen via the Block command and then scrolling) were still not displaying in the expected colour. I managed to track down which colour was displaying but this seems to have no relationship to the colour number in Dpaint i.e. in Dpaint I made one bob out of colour 5 but BB was displaying it as colour 19? Any ideas why?

[Daedalus]

That's very odd. BOBs should match the palette 1:1. Are you sure you're not inadvertently poking a colour register somewhere during the screen setup?

As for the sprites, you shouldn't need a 32-colour screen to do that, but you do need a 32-colour palette object, rather than using the screen structure's own internal colours.

[Havie]

Nope I don't do anything clever. I will post my code so you can see what I do (and maybe find out what I'm doig wrong).

[Havie]

Here it is - all graphics are 32 colour for simplicity and palette is 32 colours saved from Dpaint. Coll 19 is set as a colour for the sprite to collide with but in Dpaint I have to change colour 5 to change colour 19 in Blitz - go figure!

WBStartup

LoadShape 0,"graphics/bl1"
LoadShape 1,"graphics/bl2"
LoadShape 2,"graphics/bl3"
LoadShape 3,"graphics/bl4"
LoadShape 4,"graphics/bl5"
LoadShape 5,"graphics/bl6"
LoadShape 6,"graphics/bl7"



LoadShape 20,"graphics/run1"
LoadShape 21,"graphics/run2"

LoadShape 30,"graphics/catus1"
LoadShape 31,"graphics/cactuts2"
LoadShape 32,"graphics/cactuts3"
LoadShape 33,"graphics/cactuts4"


LoadPalette 0,"graphics/palette.pal"  <--- 32 colour palette saved from Dpaint


GetaSprite 0,20

BLITZ

SetColl 19,5
DoColl

;set up foreground bitmap...
;
BitMap 0,346,200,5

InitCopList 0,44,200,5,8,32,0

CreateDisplay 0

Use BitMap 0: Cls 31

DisplayPalette 0,0

a=0 :sp=2
x1=50:y1.f=150: an=1: jump=0: jj.f=8

cactus=0:level=2 :ct=100
score=0 :count=0

For n= 0 To 320 Step 16
      bk=Int (Rnd(6))
      If bk=6 Then Block bk,n,167
      If  bk<>6 Then Block bk,n,180

Next n


While Joyb(0)=0

  If Joyb(1)=1 AND jump=0  Then jump=1
  If jump=1 Then jj=jj-.5: y1=y1-jj: If jj=0 Then jump=2
  If jump=2 Then jj=jj+.5: y1=y1+jj: If jj>7  Then jump=0:jj=8

    If a=0
      bk=Int (Rnd(6))
      If bk=6 Then Block bk,321,167
      If  bk<>6 Then Block bk,321,180

    End If

    If cactus>ct
    bk=Rnd(4)+30
    Block bk,321,146: cactus=0 :ct=100-Rnd((level-2)*10)
    End If

   cactus=cactus+Rnd(level)

    a=a+sp: If a>15  Then a=0

   ;wait for vertical blank
   VWait

   BitMapOutput 0: Locate 1,1:Print "SCORE  ":Print Int(score)

   score=score+.1 :count=count+.1: If count>100 Then level=level+1:      count=0

    Scroll sp,150,337,46,0,150

  If  an<6 Then DisplaySprite 0,0,x1,y1,0
  If  an>5 Then DisplaySprite 0,0,x1,y1,0

  an=an+1
  If an=5 Then GetaSprite 0,20
  If an=11 Then an=0: GetaSprite 0,21

DoColl

   If PColl(0)=True Then Stop

  DisplayBitMap 0,0,0

Wend

[Havie]

By the way, I know I can't spell cactus!

[Daedalus]

Hmmm, I don't see anything untoward there with a quick look, though the SetColl command makes me suspicious, since it uses the two colours you're talking about. What happens if you commend out the SetColl line, or change it to different registers? It shouldn't affect anything, but it could be bugged.

[Cylon]

The two 'GetAsprite' inside the loop look suspicious. Why not switching the sprite without grabbing/converting a 'new' one from the Shape?
Also, make sure you have saved those single file shapes (brushes) correctly with the same number of colours you need.

[Havie]

Originally Posted by Cylon

The two 'GetAsprite' inside the loop look suspicious. Why not switching the sprite without grabbing/converting a 'new' one from the Shape?
Also, make sure you have saved those single file shapes (brushes) correctly with the same number of colours you need.

I can confirm that the colours are ok as I have just used a 32 palette and 32 colour bobs.

Not sure what you mean about grabbing/converting - can you explain please.

[Daedalus]

Originally Posted by Havie

Not sure what you mean about grabbing/converting - can you explain please.

You can create all the sprite objects you need outside the main loop and then just display different sprites as needed. This saves time copying the object around in memory, potentially slowing the loop down, and instead just using

DisplaySprite 0,MySprite,x1,y1,0

Where MySprite is the sprite image you want to show.

[Havie]

Righto so I can have lots of sprite objects - I was confused and thought I was only allowed 8! That makes sense - I will modify my code.

Still very confused by the whole colour thing - I wonder if it is an WinUAE issue? Will try running my game on my real 1200 to see what happens.

[Daedalus]

Yep, sprite *channels* are limited to 8, but you can have as many sprites objects as you specify in the compiler options, chip RAM permitting. You just decide which sprite object to show in each of the 8 channels at any one time.

I haven't had a chance to look at your code properly but might do over the next few days if I get a chance, see what's going on. Good idea to test it on real hardware - I can't imagine WinUAE would have such a glaring bug but you never know.

[Amiga1992]

I have an even stupider question here.
I recently found out about Amiblitz. So now I am confused about whether I should use Amiblitz or Blitz Basic 2.x? Stil lunsure if Amiblitz would let me create ocs/ecs games like the old one.

[edit] One more: is there a way to work with a PC IDE for this, maybe even compile with one? It would make everything faster.
Not really keen on burning my eyes staring at a 50/60Hz low res screen to make anything, really.
I think someone made a notepad++ notation file for Blitz, this would be ideal scenario, I love notepad++ I use it for all my coding experiments

[idrougge]

I think you'd want the real Blitz 2, since AmiBlitz introduces FPU dependencies when you least expect it. So it's of no use if you want to make traditional games and demos for traditional machines.


Here's the thread about Notepad++ as a development environment for Blitz: http://eab.abime.net/showthread.php?t=86316

[Amiga1992]

Yes I found the thread after mentioning it, thanks!
It's a shame that there's no cross-platform compiler for this. But I guess I can use WinUAE maxed out at speed.

Thanks!

[idrougge]

It's not as though compiling in Blitz is slow. It's basically just a bunch of assembler macros.