Setting up arrays for variable names

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jaccar09

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Joined: 27th Apr 2011

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Posted: 27th Apr 2011 19:26

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i'm not sure of the title myself...

anyway i'm trying to make a 3d virtual piano program. i already have the code and i'm sure i can do finish it in the way i'm working but i'm wondering if it could be done with less code. here's a sample code for the first key of the piano:

+ Code Snippet

if keystate(30)>0
   rotate object 1,-5,180,0
   position object 1,object position x(1),-5,0
else
   rotate object 1,0,180,0
   position object 1,object position x(1),0,0
endif

what it basically does is if A is pressed on the keyboard, it will rotate and move the first key of the piano down. if not, nothing will happen. what i did was copy this piece of code and just change the keystate scancode and the object numbers. here are the others:

+ Code Snippet

if keystate(30)>0
   press1 = 1
else
   press1 = 0
endif

+ Code Snippet

if press2 = 1 and play2 = 0
   play2 = 1
   play sound 2
endif
if press2 = 1 and play2 = 1
   play2 = 1
else
   play2 = 0
   stop sound 2
endif

after figuring out a way to make the sound play right (with the third code), i knew i was well on the way to finishing this, but i wonder if there is a way to lessen the amount of work that i would need to do if i pushed through with copy-pasting and changing numbers because there is a lot to be changed in the third code.

i guess an array could help but i don't know how that would look like, so does anybody have an idea? i know you can change numbers with a for-next loop but not numbers in variable names. i also don't want to use the same variable for all keys (such as press to indicate a key is pressed) because it should be possible to play multiple keys at once.

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Grog Grueslayer

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Joined: 30th May 2005

Playing: Green Hell

Posted: 27th Apr 2011 23:01 Edited at: 28th Apr 2011 19:27

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I would recommend making a UDT (a User Defined Type) that'll allow you greater flexibility in your keys. You could not only have sounds associated with the array but any state like a key lock that holds down a key without physically holding down a key.

You use the arrays element number as the actual KEYSTATE number so all you do is add sound numbers to the desired keys and a switch to turn on/off the pressed status.

It'd be like this (attached are some sounds):

` Create a UDT (User Defined Type)
type PianoData
 Sound as integer
 Pressed as byte
endtype

` Dimensionalize an array
dim Piano(221) as PianoData
` xx = Keystate
` Piano(xx).Sound = Sound number for key
` Piano(xx).Pressed = 0 or 1   0=Not Pressed   1=Pressed

` Define the array
Piano(30).Sound=1    ` A Key
Piano(31).Sound=2    ` S Key
Piano(32).Sound=3    ` D Key
Piano(57).Sound=4    ` Spacebar

` Load the sounds
for t=0 to 221
 
 ` Check if there's a sound to load
 if Piano(t).Sound>0
  ` Load Soundxx.wav files
  load sound "Sound"+str$(Piano(t).Sound)+".wav",Piano(t).Sound
 endif

next t

do

` Go through all the keys
 for t=1 to 221
 
  ` Make sure there is a sound for the current checked key  (no sound no check)
  if Piano(t).Sound>0
  
   ` Check if the key is being hit now but wasn't being hit previously
   if keystate(t) and Piano(t).Pressed=0
    ` Turn on pressed switch
    Piano(t).Pressed=1
    ` Loop the sound
    loop sound Piano(t).Sound
    ` Show what it's doing
    print "Pressed "+str$(t)+" key"
   endif
  
   ` Check if it's no longer being pressed after being pressed
   if keystate(t)=0 and Piano(t).Pressed=1
    ` Turn off pressed switch
    Piano(t).Pressed=0
    ` Stop the sound
    stop sound Piano(t).Sound
    ` Show what it's doing
    print "  Stopped pressing "+str$(t)+" key"
   endif
 
  endif
 
 next t

loop

+ Code Snippet

` Create a UDT (User Defined Type)
type PianoData
 Sound as integer
 Pressed as byte
endtype

` Dimensionalize an array
dim Piano(221) as PianoData
` xx = Keystate
` Piano(xx).Sound = Sound number for key
` Piano(xx).Pressed = 0 or 1   0=Not Pressed   1=Pressed

` Define the array
Piano(30).Sound=1    ` A Key
Piano(31).Sound=2    ` S Key
Piano(32).Sound=3    ` D Key
Piano(57).Sound=4    ` Spacebar

` Load the sounds
for t=0 to 221
 
 ` Check if there's a sound to load
 if Piano(t).Sound>0
  ` Load Soundxx.wav files
  load sound "Sound"+str$(Piano(t).Sound)+".wav",Piano(t).Sound
 endif

next t


do

 ` Go through all the keys
 for t=1 to 221
 
  ` Make sure there is a sound for the current checked key  (no sound no check)
  if Piano(t).Sound>0
  
   ` Check if the key is being hit now but wasn't being hit previously
   if keystate(t) and Piano(t).Pressed=0
    ` Turn on pressed switch
    Piano(t).Pressed=1
    ` Loop the sound
    loop sound Piano(t).Sound
    ` Show what it's doing
    print "Pressed "+str$(t)+" key"
   endif
  
   ` Check if it's no longer being pressed after being pressed
   if keystate(t)=0 and Piano(t).Pressed=1
    ` Turn off pressed switch
    Piano(t).Pressed=0
    ` Stop the sound
    stop sound Piano(t).Sound
    ` Show what it's doing
    print "  Stopped pressing "+str$(t)+" key"
   endif
 
  endif
 
 next t

loop

The amount of keys you can press at the same time depends on the users keyboard. Some allow only 4 keys at a time while others go up to 7. I only know of one keyboard that can detect 26 keys at a time.

The Ultimate Keyboard:
http://www.amazon.com/Microsoft-JQD-00001-SideWinder-X4-Keyboard/dp/B002ZV51DI

An article about keyboards:
http://www.microsoft.com/appliedsciences/content/projects/AntiGhostingExplained.aspx

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jaccar09

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Joined: 27th Apr 2011

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Posted: 28th Apr 2011 09:54

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wow, thanks grog! i think i've read something about UDTs but i didn't think i understood it back then haha

i finished it with copy-paste then number tweaking here and there and it ended up in 619 lines. with your code i was able to squeeze it into 158 (with a few for-next loops for recurring lines of code all over)! haha, it was a bit hard to understand at first but i finally got what it did so i also included the code to make the 3d keys to show that they're pressed.

thanks again!

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Grog Grueslayer

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Joined: 30th May 2005

Playing: Green Hell

Posted: 28th Apr 2011 19:42

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Quote: "with your code i was able to squeeze it into 158"

Np, I'm glad to help you reduce code.

Quote: "it was a bit hard to understand at first but i finally got what it did"

Yeah, sorry about that. I usually explain in the message a bit more about what the code is actually doing but I was in a rush. I'm happy that you understood without a lengthy explanation.

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