Loop an Array to display items sequentially is it possible?

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Levanthus

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Joined: 17th Apr 2003

Location: Cumbria, UK

Posted: 11th Aug 2014 17:16

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Ok i have another query about arrays, since they are the bane of my existence but damned useful... i have created an array to contain things like notes that you pick up during the game, all good, i even have a way to display them on my screen and scroll through them using arrow keys, brilliant! however... say i pick up two items:-
Slot 0 = Notebook Image
Slot 1 = Item Image 1
Slot 2 = Item Image 2
Now when i bring up my Notebook it automatically shows Slot 0 image if i press the right key it displays item one and again it will display item 2 what i need is:- If i press the right key for a third time it will loop back to the beginning and display the 0 slot image... does that make sense?

This Routine is how I scroll through the items in the array:-

+ Code Snippet

If Rightkey()=1 And ButtonTimer=0 and NFlag=1
    If Sprite exist (NoteThing().NoteImg) then Delete sprite NoteThing().NoteImg
    Next Array Index NoteThing()
        Gosub UpdateNote   
endif

And this is the subroutine that displays the items:-

+ Code Snippet

UpdateNote:
Nx=Screen Width()/2 : Ny=Screen Height()/2
    play Sound 7
        BtnOn = 0 : NFlag=1
        ButtonTimer = 20
    if NoteThing().NoteImg>0
        sprite NoteThing().NoteImg,Nx-image width(NoteThing().NoteImg)/2,Ny-Image Height(NoteThing().NoteImg)/2,NoteThing().NoteImg
    EndIf    
Return

So far if i press Right a third time it gives me an array out of bounds error message so i just need it to start over again, i've tried many things but none have worked. Cheers.

I can see from your smile, you're not here for the sunset

Windows 7 64 bit, AMD Phenom II x4 Black edition, 7 GB Ram, Radeon HD 4650, 3.6 TB HDD

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TheComet

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Joined: 18th Oct 2007

Location: I`m under ur bridge eating ur goatz.

Posted: 11th Aug 2014 17:27

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I don't know where this is coming from, but stop using next array index. The individual fields of an array are supposed to be accessed by an index.

+ Code Snippet

type Foo_t
    bar as integer
endtype

dim foo(3) as Foo_t

foo(0).bar = 5
foo(1).bar = 7
foo(2).bar = 9

See the numbers between the brackets? Those specify which index of the array should be accessed.

If your goal is to have an active item selected from within the array, then make a variable that holds an index of the active item, such as:

+ Code Snippet

activeItem = 1
foo(activeItem).bar = 7

An "Array out of bounds" error occurs when you specify a number greater than the array size. In the above example, specifying foo(3).bar = 11 would cause this error because the array is currently only size 2.

hands are ruined by repetitive stroking... - Mr. V, 2014

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WickedX

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Joined: 8th Feb 2009

Location: A Mile High

Posted: 11th Aug 2014 17:44 Edited at: 11th Aug 2014 17:45

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Darkbasic array’s can use the internal array index. But, as TheComet suggested, array’s are a lot easier to work with if you use an implicit array index. If you prefer working with the internal array index, try something like this.

+ Code Snippet

type t_Test
   name as string
endtype

dim Test() as t_Test

array insert at bottom Test()
Test().name = "Brian"
array insert at bottom Test()
Test().name = "Frank"
array insert at bottom Test()
Test().name = "Jeff"

sync on
sync rate 60

backdrop on

array index to top Test()

do
   set cursor 0, 0
   print Test().name

   if (rightkey() and keyDelay=0)
      keyDelay = 10
      next array index Test()
      if (array index valid(Test())=0)
         array index to top Test()
      endif
   endif

   if (keyDelay)
      dec keyDelay
   endif

   sync
loop

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Levanthus

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Joined: 17th Apr 2003

Location: Cumbria, UK

Posted: 11th Aug 2014 17:49 Edited at: 11th Aug 2014 18:00

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So, from what i gather you mean is i should have like:-

+ Code Snippet

NPos=0
If Rightkey()=1 And ButtonTimer=0 and NFlag=1
    If Sprite exist (NoteThing(NPos).NoteImg) then Delete sprite NoteThing(NPos).NoteImg
    If NPos=> Array count (NoteThing())
        NPos=0
    ELSE    
        NPos=NPos+1
    EndIf
        Gosub UpdateNote   
endif

UpdateNote:
Nx=Screen Width()/2 : Ny=Screen Height()/2
    play Sound 7
        BtnOn = 0 : NFlag=1
        ButtonTimer = 20
    if NoteThing(NPos).NoteImg>0
        sprite NoteThing(NPos).NoteImg,Nx-image width(NoteThing(NPos).NoteImg)/2,Ny-Image Height(NoteThing(NPos).NoteImg)/2,NoteThing(NPos).NoteImg
    EndIf    
    sprite 1999,mousex(),mousey(),100 
Return

yes?

I can see from your smile, you're not here for the sunset

Windows 7 64 bit, AMD Phenom II x4 Black edition, 7 GB Ram, Radeon HD 4650, 3.6 TB HDD

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Libervurto

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Joined: 30th Jun 2006

Location: On Toast

Posted: 11th Aug 2014 23:56

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Your array name is a bit clumsy. Wouldn't it be nicer to change NoteThing(n).NoteImg to Note(n).image?
Good thinking to store half the screen width and height in variables, but the names NX and NY don't tell us what they are.
On this occasion storing the width/height divided by two doesn't actually save us any processing as these values are involved
in a division by two anyway (you will see what I mean from the code), but it is still worth storing the screen width and height in
variables, I will just give them more descriptive names.
I have turned updateNote into a function. Can you see why I thought it would work better as a function than a subroutine?
I have also added the SilKey function which is great for managing input.

+ Code Snippet

screenW = screen width()
screenH = screen height()

maxNote = 2
thisNote = 0

do
  rem SilKey helps manage your input ;)
  scrollNotes = silkey(rightkey(), scrollNotes)

  if scrollNotes = 1
    inc thisNote
    if thisNote > maxNote then thisItem = 0
    Fn_updateNote( NoteThing(NPos).NoteImg )
  endif
loop

// Functions ///////////////////////////////////////

rem Silverman's Key Detection Function
rem return values: 0=idle; 1=pressed; 2=released; 3=held
function silkey(trigger,oldstate)
    newstate = 3&&(oldstate<<1||trigger)
endfunction newstate
//

function Fn_updateNote(img)
    play Sound 7

    if img > 0
        sprite img, (screenW - image width(img))/2, (screenH - image height(img))/2, img
    endif    

    rem What is this and why is it here?
    sprite 1999,mousex(),mousey(),100 
endfunction
//

Formerly OBese87.

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DarkBASIC Professional Discussion / Loop an Array to display items sequentially is it possible?