'taken from SimpleSi's QuickBasic/QBasic Page
'http://www.geocities.com/SiliconValley/Pines/5738/index.htm

'*** Program to fade in and out multiple lines of text.
'*** Or fade in and out a screen.
'*** Any questions?  Reach me at 'dkostka@salsgiver.com'

'*** Please note that these are two totally different examples and they
'    don't need to be used together.
Textdemo:  '*** This one will fade in and out text only.
  DIM Text(10) AS STRING
  Clr = 15       '*** Palette index color to use
  SlpDly = .1     '*** Number of seconds to show each line
  BluClr = 63     '*** These define the color that the text will be.
  GrnClr = 63     '    The numbers can be from 0 to 63, 63 being the
  RedClr = 63    '    brightest.
  ST = .05'SPEED
  Text(1) = "This is an example of how to fade in and out text."
  Text(2) = "In order to do this, first set the color you're using to black,"
  Text(3) = "then gradually bring it back to normal color.  If you want"
  Text(4) = "several faded message, then gradually make it black again,"
  Text(5) = "then print the next message, and bring it to normal color."

  CLS
  COLOR Clr
  SCREEN 12
  PALETTE Clr, 0
  FOR A = 1 TO 5
    CLS
    PRINT Text(A)
    FOR I = .001 TO 1 STEP ST
      PALETTE Clr, 65536 * INT(BluClr * I) + 256 * INT(GrnClr * I) + INT(RedClr * I)
    NEXT I
    'SLEEP SlpDly
    FOR I = .999 TO 0 STEP -ST
      PALETTE Clr, 65536 * INT(BluClr * I) + 256 * INT(GrnClr * I) + INT(RedClr * I)
    NEXT I
  NEXT A
  SCREEN 0
  SLEEP
  GOTO Fadedemo
  END

Fadedemo:
  SCREEN 12
 
  '*** First we need something on the screen.
  FOR I = 1 TO 200
    LINE (INT(RND * 640) + 1, INT(RND * 480) + 1)-(INT(RND * 640) + 1, INT(RND * 480) + 1), INT(RND * 16)
  NEXT I

  '*** These set the color intensities to arrays.  This is the normal palette
  '    so son't worry if you can't understand it.  This will only work in
  '    screen mode having at least 16 colors.  For screen modes withe more,
  '    it will only fade the first 16.
  DIM Red(16)
  Red(1) = 0: Red(2) = 0: Red(3) = 0: Red(4) = 0: Red(5) = 42: Red(6) = 42
  Red(7) = 42: Red(8) = 42: Red(9) = 21: Red(10) = 21: Red(11) = 21: Red(12) = 21
  Red(13) = 63: Red(14) = 63: Red(15) = 63: Red(16) = 63
  DIM Green(16)
  Green(1) = 0: Green(2) = 0: Green(3) = 42: Green(4) = 42: Green(5) = 0: Green(6) = 0
  Green(7) = 21: Green(8) = 42: Green(9) = 21: Green(10) = 21: Green(11) = 63: Green(12) = 63
  Green(13) = 21: Green(14) = 21: Green(15) = 63: Green(16) = 63
  DIM Blue(16)
  Blue(1) = 0: Blue(2) = 42: Blue(3) = 0: Blue(4) = 42: Blue(5) = 0: Blue(6) = 42
  Blue(7) = 0: Blue(8) = 42: Blue(9) = 21: Blue(10) = 63: Blue(11) = 21: Blue(12) = 63
  Blue(13) = 21: Blue(14) = 63: Blue(15) = 21: Blue(16) = 63
 
  '*** This part fades the palette out
  FOR I = .99 TO 0 STEP -ST
    FOR A = 0 TO 15
      PALETTE A, 65536 * INT(Blue(A + 1) * I) + 256 * INT(Green(A + 1) * I) + INT(Red(A + 1) * I)
    NEXT A
  NEXT I
 
  '*** This fades the palette in
  FOR I = .01 TO 1 STEP ST
    FOR A = 0 TO 15
      PALETTE A, 65536 * INT(Blue(A + 1) * I) + 256 * INT(Green(A + 1) * I) + INT(Red(A + 1) * I)
    NEXT A
  NEXT I
  END