'
' HSI to RGB Conversion Tool
' By Stephen R. Pietrowicz
'
SCREEN 1,640,200,4,2
WINDOW 2,"HSI to RGB Conversion Tool By Stephen R. Pietrowicz",,0,1
DEF FN a(n) = 2*I*((S*n)+0.5)
DEF FN b(n) = 0.5+(S*n)+2*(I-0.5)*(0.5-(S*n))

GOSUB Init

MouseInput:
   GOSUB PrintVals
'
'  Wait for left mouse button to be clicked
'
   WHILE MOUSE(0) = 0 : WEND
   x = MOUSE(3):y = MOUSE(4)
'   
' Check for box boundries
'    
   IF (y < 100) OR (y > 180) THEN MouseInput
   IF (x < 50) OR (x > 550) THEN MouseInput
'
' Hue Selected 
'
   IF (y <= 130) THEN
       IF (x >= 120) AND (x <= 480) THEN
           Hue = (x - 120)
           H = Hue/360
           COLOR 0
           LINE (hx,102)-(hx,128)
           COLOR 1
           LINE (x,102)-(x,128)
           hx = x 
       END IF
'
' Saturation Selected
'
   ELSEIF (y >= 150) THEN
       IF (x <= 150) THEN
           S = (x - 50)/100 
           COLOR 0
           LINE (sx,152)-(sx,178)
           COLOR 1
           LINE (x,152)-(x,178)
           sx = x 
'
' Intensity Selected
'
       ELSEIF (x >= 450) THEN
           I = (x - 450)/100 
           COLOR 0
           LINE (ix,152)-(ix,178)
           COLOR 1
           LINE (x,152)-(x,178)
           ix = x 
       END IF
   END IF
   GOSUB Convert
   GOTO MouseInput
   
Init:
   CLS
   COLOR 3
   LINE(118,100)-(482,130),,b
   LINE(48,150)-(152,180),,b
   LINE(448,150)-(552,180),,b
   hx = 120: sx = 50: ix = 450
   COLOR 1
   LINE (hx,102)-(hx,128)
   LINE (sx,152)-(sx,178)
   LINE (ix,152)-(ix,178)
   COLOR 2
   LINE (50,25)-(550,75),,bf
   COLOR 1
   LINE (50,25)-(550,75),,b
   r = 0: g = 0: b = 0 : S = 0 : I = 0
   RETURN

'
' Change given HSI coordinates to RGB
'       
Convert:
IF H < 0.16 THEN
   Red   = 1
   Green = H*6
   Blue  = 0
ELSEIF H < 0.33 THEN
   Red   = 2 - H*6
   Green = 1 
   Blue  = 0
ELSEIF H < 0.5 THEN
   Red   = 0
   Green = 1
   Blue  = 6*H - 2
ELSEIF H < 0.66 THEN
   Red   =  0
   Green = 4 - H*6
   Blue  = 1
ELSEIF H < 0.83 THEN
   Red   = H*6 - 4
   Green = 0
   Blue  = 1
ELSE
   Red   = 1
   Green = 0
   Blue  = 6 - 6*H
END IF

Red = Red - 0.5
Green = Green - 0.5
Blue = Blue - 0.5

IF (I <= 0.5) THEN
    Red   = FN a(Red)
    Green = FN a(Green) 
    Blue  = FN a(Blue)
ELSE
    Red   = FN b(Red)
    Green = FN b(Green)
    Blue  = FN b(Blue)
END IF

IF Red > 1 THEN Red = 1
IF Green > 1 THEN Red = 1
IF Blue > 1 THEN Red = 1
IF Red < 0 THEN Red = 0
IF Green < 0 THEN Green = 0
IF Blue < 0 THEN Blue = 0

PALETTE 2,Red,Green,Blue
RETURN

PrintVals:
   COLOR 3
   LOCATE 2,22
   PRINT USING "Red   = #.##   ";Red;
   PRINT USING "Green = #.##   ";Green;
   PRINT USING "Blue  = #.##";Blue
   LOCATE 12, 34    
   PRINT USING "Hue = ###";Hue
   LOCATE 18, 5
   PRINT USING "Saturation = #.##";S
   LOCATE 18, 55
   PRINT USING "Intensity = #.##";I 
   COLOR 2
RETURN