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Go: HSV to RGB
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package bake | |
import ( | |
"errors" | |
"image/color" | |
"math" | |
) | |
// https://en.wikipedia.org/wiki/HSL_and_HSV#Converting_to_RGB | |
func HSVToRGBA(h float64, s float64, v float64) (*color.RGBA, error) { | |
if h < 0.0 || h > 1.0 { | |
return nil, errors.New("hue must be in [0.0, 1.0]") | |
} | |
if s < 0.0 || s > 1.0 { | |
return nil, errors.New("saturation must be in [0.0, 1.0]") | |
} | |
if v < 0.0 || v > 1.0 { | |
return nil, errors.New("lightness must be in [0.0, 1.0]") | |
} | |
c := v * s | |
h_prime := h * 6.0 | |
x := c * (1 - math.Abs(math.Mod(h_prime, 2.0)-1.0)) | |
var r, g, b float64 | |
switch { | |
case 0 <= h_prime && h_prime < 1: | |
r, g, b = c, x, 0 | |
case 1 <= h_prime && h_prime < 2: | |
r, g, b = x, c, 0 | |
case 2 <= h_prime && h_prime < 3: | |
r, g, b = 0, c, x | |
case 3 <= h_prime && h_prime < 4: | |
r, g, b = 0, x, c | |
case 4 <= h_prime && h_prime < 5: | |
r, g, b = x, 0, c | |
case 5 <= h_prime && h_prime < 6: | |
r, g, b = c, 0, x | |
} | |
m := v - c | |
return &color.RGBA{ | |
uint8((r + m) * 255), | |
uint8((g + m) * 255), | |
uint8((b + m) * 255), | |
255, | |
}, nil | |
} |
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