Hsv

Hsv (Function)

Format

hsv ( hue, saturation, value )
hsv ( hue, saturation, value, alpha )

returns integer_expression

Description

Returns the ARGB value of a colour described by its hue, saturation and value rather than by how much red, green and blue it holds. The number it gives back is the same kind of colour Rgb gives, so it can be used anywhere a colour can: in Color, Clg, ImageNew and the rest.

• hue is the position on the colour wheel, in degrees from 0 to 360: 0 is red, 60 yellow, 120 green, 180 cyan, 240 blue, 300 magenta, and 360 is red again.
• saturation is how strong the colour is, from 0 to 100: 0 is a grey and 100 is the pure colour.
• value is how bright it is, from 0 to 100: 0 is black whatever the hue and saturation, and 100 is as bright as the colour goes.
• alpha is how opaque it is, from 0 (fully transparent) to 100 (fully opaque). If it is left out, 100 is used.

All four may be fractions, so a hue can move round the wheel in small steps without jumping. A value outside its range raises error 141.

HSV is the easier of the two when a program wants to move through colours rather than name one: counting the hue from 0 to 360 walks through the whole rainbow with a single number, and lowering the value darkens a colour without changing what colour it is.

Note that alpha is a percentage here, like the other three, and not 0 to 255 as it is for Rgb: hsv(0, 100, 100, 50) is the same half-transparent red as rgb(255, 0, 0, 128).

Example

# a colour wheel: the hue goes round the circle and the
# saturation grows from grey in the middle to full at the edge
fastgraphics
clg black
for r = 0 to 240 step 3
   for a = 0 to 359
      color hsv(a, r / 240 * 100, 100)
      circle 250 + r * cos(radians(a)), 250 - r * sin(radians(a)), 3
   next a
next r
refresh

draws

See Also

Color, GetBrushColor, GetColor, Rgb

History

2.3.0	New To Version