Mandelbrot set in FB

hello there nice to be here

here is a small demo in Freebasic of Mandelbrot set


#INCLUDE "fbgfx.bi"


CONST AS INTEGER WIDTH_screen = 1000
CONST AS INTEGER HEIGHT_screen = 1000

DIM SHARED AS double min_num = -2.84
DIM SHARED as double max_num = 1.0
DIM SHARED AS double factor = 1
DIM SHARED AS INTEGER MAX_ITERATIONS = 200


function map( value AS double, in_min AS Double, in_max AS Double, out_min AS double, out_max AS Double) AS double

   return (value - in_min) * (out_max - out_min) / (in_max - out_max) + out_min

END FUNCTION



SUB PRINTtoSCREEN(x AS INTEGER, y AS INTEGER, red AS Ulong, green AS Ulong, blue AS ULONG)

  pset(x,y),RGBA(red,green,blue,255)

END SUB



SUB main()

  SCREENRES WIDTH_SCREEN, HEIGHT_SCREEN, 32

  DIM counter AS INTEGER = 0
 

  WHILE TRUE:

     max_num -= 0.1*factor
     min_num += 0.15 * factor

     factor *= 0.9349

     MAX_ITERATIONS += 5
     

     FOR x AS INTEGER = 0 TO WIDTH_SCREEN - 1
        FOR y AS INTEGER = 0 TO HEIGHT_screen - 1
           IF INKEY() = "q" THEN END
           
           DIM AS double a = map(x, 0, WIDTH_screen, min_num, max_num)
           DIM AS double b = map(y, 0, WIDTH_screen, min_num, max_num)
           DIM AS double ai = a
           DIM AS double bi = b

           DIM AS INTEGER n = 0

           FOR i AS INTEGER = 0 TO MAX_ITERATIONS

              DIM AS DOUBLE a1 = a * a - b * b
              DIM AS DOUBLE b1 = 2 * a * b

              a = a1 + ai
              b = b1 + bi

              IF ((a+ b) > 20 ) THEN EXIT FOR

              n += 1

           NEXT

           DIM bright AS INTEGER = (MAP(n, 0, MAX_ITERATIONS, 0 , 255))

           IF ((n = MAX_ITERATIONS)) THEN ' maybe add OR bright > 20

              bright = 0

           ENDIF


           'DIM AS ULONG red = MAP(bright * bright, 0 , 6502, 0, 255)
           'DIM AS ULONG green = bright
           'DIM AS ULONG blue = MAP(SQR(bright), 0, sqr(255), 0, 255)

           DIM AS Ubyte red = MAP(bright * bright, 0 , 6502, 0, 255)
           DIM AS Ubyte green = bright
           DIM AS Ubyte blue = MAP(SQR(bright), 0, sqr(255), 0, 255)
         

           SCREENLOCK()

           PRINTTOSCREEN(x,y,red,green,blue)

           SCREENUNLOCK()

        NEXT
     NEXT

     counter +=1

  WEND

END SUB

MAIN()



ron77