_HSB32

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The _HSB32 function specifies a color using the HSB colorspace and returns the 32-bit ARGB color value representing the color with the specified hue, saturation and brightness.


Syntax

color32value~& = _HSB32(hue#, saturation#, brightness#)


Parameters

  • hue# specifies the hue DOUBLE of the desired color from 0 to 360 degrees.
    • The color wheel starts with red(0), turns to yellow(60), green(120), cyan(180), blue(240), magenta(300) to red(360) again.
    • Mixed colors can be build by specifying values between the 6 base color angles.
  • saturation# specifies the saturation DOUBLE of the desired color from 0 to 100 percent.
    • 100% is the richest color possible, as closer you come to 0%, as more the color is fading ending at dull gray.
    • The intensity of the gray (i.e. black >> darkgray >> midgray >> lightgray >> white) depends on the brightness# value.
  • brightness# specifies the brightness DOUBLE of the desired color from 0 to 100 percent.
    • 100% is the brightest (highest intensity), as closer you come to 0%, as darker is the color always ending in black regardless of the given hue# and saturation#.


Description

  • The value returned is always a 32-bit _UNSIGNED LONG ARGB color value, as is the POINT value.
  • Return variable types must be _UNSIGNED LONG or LONG, otherwise the resulting color may lose the _BLUE value.
  • Parameter values outside the allowed ranges are clipped.
  • All colors build with this function are opaque (full alpha), i.e. it returns _UNSIGNED LONG 32-bit hexadecimal values from &HFF000000 to &HFFFFFFFF.
  • Use _HSBA32 if you also need control over the alpha channel.
  • When (_UNSIGNED) LONG values are PUT to file, the ARGB values become BGRA. Use LEFT$(MKL$(color32value~&), 3) to place 3 colors.
Naming differences
  • The HSB (B=Brightness) colorspace is also known as HSV (V=Value) and sometimes even called HSI (I=Intensity), but that's all just different names for the same thing.
  • However, this function is not suitable for the HSL (L=Lightness) colorspace, which is widely used in the Web/CSS.
Precision drawbacks
  • When converting between colorspaces, rounding errors can occur. While the HSB colorspace has virtually infinite precision only limited by the used floating point type, RGB is represented in 8-bit integers (0-255) only, which can lead to quantization errors. In fact, not all colors in HSB can be accurately represented in RGB and vice versa.
  • However, if you limit yourself to only passing integer values to _HSB32 or _HSBA32, just as you do for the respective RGB colorspace functions _RGB32 or _RGBA32, then you can get back that exact values by CINTing the results returned by _HUE32, _SATURATION32 and _BRIGHTNESS32.


Availability


Examples

Example 1
Drawing a color wheel by looping through hue and saturation.
SCREEN _NEWIMAGE(640, 480, 32)

FOR ang# = 0 TO 360 STEP 0.25
    FOR rad# = 0 TO 200 STEP 0.25
        x% = rad# * COS(_D2R(ang#))
        y% = rad# * SIN(_D2R(ang#))
        PSET (320 + x%, 240 - y%), _HSB32(ang#, rad# / 2, 100)
    NEXT rad#
NEXT ang#

END

Example 2
Drawing a 3D model of the HSB colorspace with a cut to see inside.
SCREEN _NEWIMAGE(640, 480, 32)

FOR hei# = 0 TO 200 STEP 5
    FOR ang# = 5 TO 285 STEP 0.25
        FOR rad# = 0 TO 200 STEP 1
            x% = rad# * COS(_D2R(ang#))
            y% = rad# * SIN(_D2R(ang#))
            z% = hei#
            XYfrom3D x%, y%, z%
            PSET (330 + x%, -z% + 340), _HSB32(ang#, rad# / 2, hei# / 2)
            IF rad# = 0 _ANDALSO (hei# = 0 OR hei# = 200) THEN
                IF hei# = 0 THEN
                    IF ang# = 5 THEN bmpx% = 330 + x%: bmpy% = -z% + 340
                ELSE
                    IF ang# = 5 THEN tmpx% = 330 + x%: tmpy% = -z% + 340
                END IF
            ELSEIF rad# = 200 _ANDALSO (hei# = 0 OR hei# = 200) THEN
                PSET (330 + x%, -z% + 340), &HFFFFFFFF
                IF hei# = 0 THEN
                    IF ang# = 5 THEN bspx% = 330 + x%: bspy% = -z% + 340
                    IF ang# = 285 THEN bepx% = 330 + x%: bepy% = -z% + 340
                ELSE
                    IF ang# = 5 THEN tspx% = 330 + x%: tspy% = -z% + 340
                    IF ang# = 285 THEN tepx% = 330 + x%: tepy% = -z% + 340
                END IF
            END IF
        NEXT rad#
    NEXT ang#
NEXT hei#
LINE (bspx%, bspy%)-(bmpx%, bmpy%), &HFFFFFFFF
LINE (bmpx%, bmpy%)-(bepx%, bepy%), &HFFFFFFFF
LINE (tspx%, tspy%)-(tmpx%, tmpy%), &HFFFFFFFF
LINE (tmpx%, tmpy%)-(tepx%, tepy%), &HFFFFFFFF
LINE (bspx%, bspy%)-(tspx%, tspy%), &HFFFFFFFF
LINE (bmpx%, bmpy%)-(tmpx%, tmpy%), &HFFFFFFFF
LINE (bepx%, bepy%)-(tepx%, tepy%), &HFFFFFFFF
END

SUB XYfrom3D (x%, y%, z%)
x% = (x% + (y% * .5))
z% = (z% + (y% * .5))
END SUB


See also



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