backdrop on
color backdrop 0
sync on
sync rate 0
hide mouse

Global width = 640
Global height = 480

type particle
   x as float
   y as float
   vx as float
   vy as float
   f as float
   g as float
   color as dword
endtype


amount = 3000
dim rain(amount) as particle

for t = 1 to amount
   rain(t).x = rnd(width)
   rain(t).y = rnd(height)
   rain(t).color = rgb(0,0,255)
next t


repeat

   lock pixels

   for t = 1 to amount
      oldx = rain(t).x
      oldy = rain(t).y
      rain(t).x = rain(t).x + rain(t).vx*rain(t).f
      rain(t).y = rain(t).y + rain(t).vy*rain(t).f + rain(t).g
      if rain(t).g < 5 then rain(t).g = rain(t).g + 0.01
      if rain(t).f > 0
         rain(t).f = rain(t).f - 0.1
      else
         rain(t).f = 0
      endif


      rem if rain hits ball
      if ((rain(t).x-mousex())^2 + (rain(t).y-mousey())^2) <= 100
         x# = (rain(t).x - mousex())/10.0
         y# = (rain(t).y - mousey())/10.0

         rain(t).vx = x#
         rain(t).vy = y#
         rain(t).f = 4
      endif
      if rain(t).y >= height OR rain(t).y <= 0 OR rain(t).x >= width OR rain(t).x <= 0
         rain(t).x = rnd(width)
         rain(t).y = 1
         rain(t).vx = 0
         rain(t).vy = 0
         rain(t).g = 0
         `rain(t).color = rgb(200,200,rnd(55)+200)
         rain(t).color = rgb(0,0,255)
      endif


      angle = wrapvalue(atanfull(oldx-rain(t).x,oldy-rain(t).y))
      pDot(rain(t).x,rain(t).y,rain(t).color)

      for i = 1 to 6
         x = rain(t).x + sin(angle)*i
         y = rain(t).y + cos(angle)*i
         pDot(x,y,rgb(0,0,255-i*30))
      next i
   next t

   unlock pixels

   circle mousex(), mousey(),10

   sync
until spacekey()


function frictionDirection#(f as float)
   if f > 0 then exitfunction 1
   if f < 0 then exitfunction -1
endfunction 0


REM function borrowed from Coding Fodder's Rain code
function pDot(x as integer, y as integer, color_value as dword )
   if x > 0 and x < width and y > 0 and y < height
      start = get pixels pointer()
      repeat_number = get pixels pitch()
      bits_per_pixel = bitmap depth(num)/8
      pointer = start + y*repeat_number + x*bits_per_pixel
      *pointer = color_value
   endif
endfunction