aUCBLogo Demos and Tests / bouncingparticles

be bouncingparticles
   part 1000 4
end

be part partnum :pensize
   intrepeat=10000
   partx=(array partnum 1)
   partv=array partx
   parta=array partx
   partcolor=array partx
   partbounces=array partx
   trails=false

   setUpdateGraph false
   setPointSize :pensize
   disablePointSmooth
;   enablePointSmooth
   cs ht pu setpc [50 230 20]
   setx 0 sety -200 - :pensize
   pd rt 90 fd 1000 pu home pd
   OnMouseLeftDown [trails=true]
   OnMouseRightDown
   [   cs ht pu setpc [50 230 20]
      setx 0 sety -200 - :pensize
      pd rt 90 fd 1000 pu home pd
      trails=false
   ]
   repeat partnum
   [   j=repcount
      partx.j=Float List 0 0
      partv.j=List rnd-0.5 (rnd+1)
      parta.j=List 0.0 -0.01
      partbounces.j=Int 0
      partcolor.j=HSB 360*j/(partnum+1) 1 1
   ]
   norefresh
   forever
   [   if not trails [clearScreen]
      partx+=partv
      partv+=parta
      repeat partnum
      [   if partx.repcount.2 < -200
         [   j=repcount
            partx.j.2=-199.99
            partv.j.2=-partv.j.2/1.5
            partbounces.j=partbounces.j+1
            if partbounces.j==10
            [   partx.j=Float List 0 0
               partv.j=List rnd-0.5 (rnd+1)
               partbounces.j=Int 0
            ]
         ]
      ]
      setPixel partx partcolor
      if Key? [break]
      updateGraph
   ]
end