Source: geocities.com/thechange/bigbang

               ( geocities.com/thechange)    
; TheChange@yahoo.com

Const ScreenSizeX = 1280
Const ScreenSizeY = 1024

Const StarMax = 50000  ; You may want to cut down on the number of stars

; Speed of the stars, depth of starfield and starfactor (square radius)
; are the main visual controls.

Const StarSpeed = 100
Const StarDepth# = 1200
Const StarFactor# = 20
Const StarZoom# = 1.0333

Type Star
  Field X#       ; Positions
  Field Y#
  Field Z#
  Field SpeedX#  ; Velocities
  Field SpeedY#
  Field SpeedZ#
  Field Red      ; Each star has its individual color/shade
  Field Green
  Field Blue
End Type

SeedRnd MilliSecs()

Graphics ScreenSizeX , ScreenSizeY

; Star positions, velocities and colors are pre-generated.

Local Star.Star
Color 255 , 255 , 255
For Counter = 1 To StarMax
  Star = New Star

  Star\X = 0  ; All stars together at the beginning
  Star\Y = 0
  Star\Z = StarDepth / 2

  Angle# = Rnd ( 360 )  ; Stars will move in a circular manner
  Distance# = Rnd ( StarSpeed ) * StarFactor
  Star\SpeedX = GetVectorX ( Distance , Angle )
  Star\SpeedY = GetVectorY ( Distance , Angle )
  Star\SpeedZ = Rnd ( -StarSpeed , StarSpeed )

  Star\Red   = 255  ; Default to white color
  Star\Green = 255
  Star\Blue  = 255
  Select Rand ( 3 )  ; 3 possible color shades
    Case 1  ; Cyan
      Star\Red   = 191 + Rand ( 63 )
    Case 2  ; Purple
      Star\Green = 191 + Rand ( 63 )
    Case 3  ; Yellow
      Star\Blue  = 191 + Rand ( 63 )
  End Select
Next

Delay 1000
SetBuffer BackBuffer()
Repeat

  LockBuffer

  For Star = Each Star

    Star\X = Star\X + Star\SpeedX  ; Update positions and speed
    Star\Y = Star\Y + Star\SpeedY
    Star\Z = Star\Z + Star\SpeedZ / StarDepth
    Star\SpeedZ = Star\SpeedZ * StarZoom

    sx = Star\X / Star\Z + ScreenSizeX / 2  ; Calculate pixel on screen (centered)
    sy = Star\Y / Star\Z + ScreenSizeY / 2

    If sx >= 0  ; Range checking
      If sx < ScreenSizeX
        If sy >= 0
          If sy < ScreenSizeY

            Grey = ( Abs ( StarDepth - Star\Z ) * 255 / StarDepth ) Mod 256 + 128
            If Grey > 255 Then Grey = 512 - Grey  ; Calculate grey scale shade

            Red   = Star\Red * Grey / 256  ; Blend with star's color
            Green = Star\Green * Grey / 256
            Blue  = Star\Blue * Grey / 256

            RGB = GetRGB ( Red , Green , Blue )
            WritePixelFast sx , sy , RGB

          End If
        End If
      End If
    End If

  Next

  UnlockBuffer

  Flip
  Cls

  ; The 'any' key
  For Key = 1 To 255
    If KeyHit ( Key )
      Done = True
      Exit
    End If
  Next
  ; The 'any' button
  For Button = 1 To 3
    If MouseHit ( Button )
      Done = True
      Exit
    End If
  Next

Until Done

End

  Function GetVectorX# ( Distance# , Angle# )  ; Get horizontal size of vector using distance and angle
    Return Sin ( Angle ) * Distance
  End Function

  Function GetVectorY# ( Distance# , Angle# )  ; Get vertical size of vector using distance and angle
    Return Sin ( Angle - 90 ) * Distance
  End Function

  Function GetRGB% ( Red% , Green% , Blue% )  ; Combine red, green and blue color components
    Return Red Shl 16 + Green Shl 8 + Blue
  End Function