Halftone - A Utility to Demonstrate 255 Colors Mixed in Screen 12

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'****************************************************************************

'

'               HALFTONE.BAS: Bob Seguin - 2003  (freeware)

'

'               A program to examine the possibilities of mixing the

'               16 basic palette colors in SCREEN 12 as halftones to

'               provide more than 16 colors on the screen at one time.

'

'               To use, send the sub program the left/top/right/bottom

'               boundaries of the shape being halftoned along with

'               ColorKEY and ToneCOLOR (the shape is in ColorKEY).

'

'         NOTE: Follow row and column from the halftone to find the

'               attribute numbers involved.

'

'     Comments: (textury, but useful in certain applications,

'               such as fabrics, wood, etc.)

'

'

'****************************************************************************



DEFINT A-Z



_TITLE "Halftone.bas by Bob Seguin"



DIM Box(1 TO 1600)

   

SCREEN 12

PALETTE 4, 63 'set default dark red to brightest red

   

LOCATE 2, 2: PRINT "0  1  2  3  4  5  6  7  8  9  10 11 12 13 14 15"

FOR x = 8 TO 384 STEP 24

    GET (x, 16)-(x + 16, 28), Box(n + 1)

    n = n + 100

NEXT x



CLS

FOR y = 0 TO 15

    FOR x = 0 TO 15

        LINE (x * 40, y * 30)-(x * 40 + 37, y * 30 + 27), y, BF

        HalfTONE x * 40, y * 30, x * 40 + 37, y * 30 + 27, y, x

    NEXT x

NEXT y



n = 0: y = 8

FOR x = 15 TO 611 STEP 40

    IF x = 415 THEN x = 411

    PUT (x, y), Box(n + 1)

    n = n + 100

    y = y + 30

NEXT x



DO: LOOP UNTIL INKEY$ <> ""

END



SUB HalfTONE (x1, y1, x2, y2, ColorKEY, ToneCOLOR)



    FOR x = x1 TO x2 STEP 2

        FOR y = y1 TO y2 STEP 2

            IF POINT(x, y) = ColorKEY THEN PSET (x, y), ToneCOLOR

            IF POINT(x + 1, y + 1) = ColorKEY THEN PSET (x + 1, y + 1), ToneCOLOR

        NEXT y

    NEXT x



END SUB