PlayBASIC Tutorial: From Variables To Arrays (Intro To Arrays) 2017-09-17

[kevin]

PlayBASIC Tutorial:  From Variables To Arrays (Intro To Arrays) 2017-09-17


Welcome programmers,  in this tutorial we're going to introduce the concept of arrays starting out from variables.  So first we build a simple game  loop that controls two characters using only variables.  The characters are represented on screen as filled circles.  After we get up to speed with the variable version we then move onto how we can use parallel integer arrays to store the various properties of the characters.  The array version can control as many or as few characters as you like, which is the benefit of Arrays over Variables


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Video:

Example #1 - Variables Example

PlayBASIC Code: [Select]

   Xpos1  = 400
   Ypos1  = 300
      
   Xpos2  = 100
   Ypos2  = 100

      
   setfps 20   
      
  do    

    cls rgb(10,20,40)

   ; Draw circle 1        
     Circle Xpos1,Ypos1, 32, true
   
     Xpos1 = Xpos1 + 2
     Ypos1 = Ypos1 - 4
  
      Xpos1 = WrapValue(Xpos1,0,800)     
       Ypos1 = WrapValue(Ypos1,0,600)     
   
   

   ; Draw circle 2      
     Circle Xpos2,Ypos2, 64, true
   
     Xpos2 = Xpos2 + 2
     Ypos2 = Ypos2 + 2
       Xpos2 = WrapValue(Xpos2,0,800)     
       Ypos2 = WrapValue(Ypos2,0,600)     
  
     sync
  loop
  
 

Example #2 - Arrays Example - Using Parallel Arrays To Store Character Properties

PlayBASIC Code: [Select]

 Setfps 20

   Number_Of_Characters = 50 

   dim Xpos( Number_Of_Characters  )
   dim Ypos( Number_Of_Characters  )
   dim size( Number_Of_Characters  )
   dim Xspeed( Number_Of_Characters )
   dim Yspeed( Number_Of_Characters )
   dim Colour( Number_Of_Characters )
   
   
   for lp = 1 to Number_Of_Characters
         Xpos(lp)  = rnd(800)
         Ypos(lp)  = rnd(600)
         Size(lp)  = rndrange(16,50)
         Xspeed(lp) = rndrange(-5, 5)
       Yspeed(lp) = rndrange(-5,5)
       Colour(lp) = rndrgb()
   next
   
   
  do 
     
        Cls rgb(0,400,20)
        
        for lp=1 to Number_Of_Characters
           
           Radius = Size(lp)

           circlec xpos(lp),ypos(lp),Radius,true,Colour(lp)
           
         //  xpos(lp) = Xpos(lp) + Xspeed(lp)
         //  ypos(lp) = ypos(lp) + Yspeed(lp)
           
           xpos(lp) = wrapvalue(xpos(lp) + Xspeed(lp) , -Radius, 800 + Radius)
           ypos(lp) = wrapvalue(ypos(lp) + Yspeed(lp) , -Radius, 600 + Radius)
                      
        next
          
        Sync
     loop