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Active Forums => Programs => Topic started by: loudar on October 16, 2020, 04:03:22 pm

Title: HSL to RGB converter - useful for graphics!
Post by: loudar on October 16, 2020, 04:03:22 pm
Hey!

Used this for a while and I think I've fixed every major bug, if you happen to have improvements I'll take them :D Give it a hue, saturation, lightness and alpha and you can read out the R, G and B values if you need to, but works nice just to shift things in color or whatever. Have fun!

Code: QB64: [Select]
  1. '-------------------------------- DEMO --------------------------------'
  2.  
  3. SCREEN _NEWIMAGE(1000, 500, 32)
  4.  
  5. 'definitions
  6. h = 0 'takes values from 0 to 359
  7. s = 1 'takes values from 0 to 1
  8. l = 1 'takes values from 0 to 1
  9. changepercycle = 5
  10.  
  12.     h = h + changepercycle 'changes the hue each loop
  13.     keyhit = _KEYHIT
  14.  
  15.     colour& = hsltorgb~&(h, s, l, 255)
  16.     COLOR colour&
  17.     PRINT h, s, l, "HSL", _RED(colour&), _GREEN(colour&), _BLUE(colour&), "RGB"
  18.     _LIMIT 60
  19. LOOP UNTIL keyhit = 13
  20.  
  23.  
  24. '-------------------------------- DEMO --------------------------------'
  25.  
  26. FUNCTION hr& (hue AS _FLOAT, saturation AS _FLOAT, lightness AS _FLOAT)
  27.     SELECT CASE hue
  28.         CASE IS < 60 AND hue >= 0: tr = 1
  29.         CASE IS < 120 AND hue >= 60: tr = 1 - ((hue - 60) / 60)
  30.         CASE IS < 180 AND hue >= 120: tr = 0
  31.         CASE IS < 240 AND hue >= 180: tr = 0
  32.         CASE IS < 300 AND hue >= 240: tr = (hue - 240) / 60
  33.         CASE IS < 360 AND hue >= 300: tr = 1
  34.     END SELECT
  35.     hr& = tr * 255
  37.  
  38. FUNCTION hg& (hue AS _FLOAT, saturation AS _FLOAT, lightness AS _FLOAT)
  39.     SELECT CASE hue
  40.         CASE IS < 60 AND hue >= 0: tg = hue / 60
  41.         CASE IS < 120 AND hue >= 60: tg = 1
  42.         CASE IS < 180 AND hue >= 120: tg = 1
  43.         CASE IS < 240 AND hue >= 180: tg = 1 - ((hue - 180) / 60)
  44.         CASE IS < 300 AND hue >= 240: tg = 0
  45.         CASE IS < 360 AND hue >= 300: tg = 0
  46.     END SELECT
  47.     hg& = tg * 255
  49.  
  50. FUNCTION hb& (hue AS _FLOAT, saturation AS _FLOAT, lightness AS _FLOAT)
  51.     SELECT CASE hue
  52.         CASE IS < 60 AND hue >= 0: tb = 0
  53.         CASE IS < 120 AND hue >= 60: tb = 0
  54.         CASE IS < 180 AND hue >= 120: tb = (hue - 120) / 60
  55.         CASE IS < 240 AND hue >= 180: tb = 1
  56.         CASE IS < 300 AND hue >= 240: tb = 1
  57.         CASE IS < 360 AND hue >= 300: tb = 1 - ((hue - 300) / 60)
  58.     END SELECT
  59.     hb& = tb * 255
  61.  
  62. FUNCTION hsltorgb~& (conH, conS, conL, conA)
  63.     IF conH >= 360 THEN conH = (conH MOD 360) * 360
  64.     IF conS > 1 THEN conS = 1
  65.     IF conL > 1 THEN conL = 1
  66.  
  67.     objR = hr&(conH, conS, conL) * conS
  68.     objG = hg&(conH, conS, conL) * conS
  69.     objB = hb&(conH, conS, conL) * conS
  70.  
  71.     'maximizing to full 255
  72.     IF objR >= objG AND objG >= objB THEN '123
  73.         factor = 255 / objR
  74.     ELSEIF objG >= objR AND objR >= objB THEN '213
  75.         factor = 255 / objG
  76.     ELSEIF objB >= objR AND objR >= objG THEN '312
  77.         factor = 255 / objB
  78.     ELSEIF objR >= objB AND objB >= objG THEN '132
  79.         factor = 255 / objR
  80.     ELSEIF objG >= objB AND objB >= objR THEN '231
  81.         factor = 255 / objG
  82.     ELSEIF objB >= objR AND objG >= objR THEN '321
  83.         factor = 255 / objB
  84.     END IF
  85.     objR = objR * factor
  86.     objG = objG * factor
  87.     objB = objB * factor
  88.  
  89.     'adjusting to lightness
  90.     objR = objR * conL
  91.     objG = objG * conL
  92.     objB = objB * conL
  93.  
  94.     'adjusting to saturation
  95.     IF objR = 0 OR objG = 0 OR objB = 0 THEN
  96.         objavg = (objR + objG + objB) / 2
  97.     ELSE
  98.         objavg = (objR + objG + objB) / 3
  99.     END IF
  100.     IF conS > 0.1 THEN
  101.         objR = objR + ((objavg - objR) * (1 - conS))
  102.         objG = objG + ((objavg - objG) * (1 - conS))
  103.         objB = objB + ((objavg - objB) * (1 - conS))
  104.     ELSE
  105.         objR = objavg
  106.         objG = objavg
  107.         objB = objavg
  108.     END IF
  109.  
  110.     hsltorgb~& = _RGBA(objR, objG, objB, conA)
Title: Re: HSL to RGB converter - useful for graphics!
Post by: bplus on October 17, 2020, 02:01:44 pm
Always liked rainbow text :)

Kind of curious where we run into HSL values in QB64?
Title: Re: HSL to RGB converter - useful for graphics!
Post by: loudar on October 18, 2020, 12:01:54 pm
I don't really know where it appears natively, but it's really useful if you have a color and want to shift it by a certain degree. Can't really do that in RGB, so an HSL->RGB function is kind of necessary when working with graphics on a more specific level. I guess there's stuff that you can import that don't really need that (there was a color picker somewhere in the forum which I guess has a conversion already?) but I wrote my own for convenience and learning, so figured I'd share it anyway :D
Title: Re: HSL to RGB converter - useful for graphics!
Post by: bplus on October 18, 2020, 04:49:41 pm
Yeah, it would be handy to cycle through all colors by just changing 1 number the h for hue I assume.

And then add lightness or darkness the l for light, maybe?

But what is saturation s? something with alpha or transparencies?
Title: Re: HSL to RGB converter - useful for graphics!
Post by: loudar on October 18, 2020, 06:24:15 pm
Saturation moves the R, G and B values closer to the average between them the smaller the value is. It's nice if you want to have things just white/grey/black or just desaturated! Can't guarantee that's the proper algorithm for it, just wanted to somehow implement it.
Title: Re: HSL to RGB converter - useful for graphics!
Post by: bplus on October 19, 2020, 12:14:41 pm
Yeah I am not seeing any work with alpha, it's just being passed through to RGBA function without change.
Title: Re: HSL to RGB converter - useful for graphics!
Post by: SMcNeill on October 19, 2020, 01:18:04 pm
Doesn’t Rhosigma’s libraries include a convertor for this?  I’m thinking it does.  If so, you might want to compare ideas and see how he does his.  ;)
Title: Re: HSL to RGB converter - useful for graphics!
Post by: bplus on October 19, 2020, 02:24:38 pm
Here is bunch of things to compare: https://www.qb64.org/forum/index.php?topic=2173.msg114193#msg114193

I bet I will see Loudar's in action in AVAR when I get to it.
Title: Re: HSL to RGB converter - useful for graphics!
Post by: RhoSigma on October 19, 2020, 03:56:58 pm
Quote from: SMcNeill on October 19, 2020, 01:18:04 pm
Doesn’t Rhosigma’s libraries include a convertor for this?  I’m thinking it does.  If so, you might want to compare ideas and see how he does his.  ;)

The converthelper.bm file in my libaries collection (IMG-Support folder) has functions for the HSB/HSV color model, according to Wikipedia there's a difference between HSB/HSV and HSL, although the models are very similar.

here's a good description:
https://medium.com/innovaccer-tech/rgb-vs-hsb-vs-hsl-demystified-1992d7273d3a

The essence in this article is:
Quote
Hence, the only difference is that in HSB, 100% Brightness can give you the White Colour only when the Saturation is 0 while in HSL 100% Lightness will give you the White Colour irrespective of the Saturation.
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