/*
Copyright (C) 2019 Leo Tenenbaum

This file is part of AutoArt.

AutoArt is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

AutoArt is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with AutoArt.  If not, see <https://www.gnu.org/licenses/>.
*/

package autoutils
import (
    "math"
)

func HSVToRGB(h uint8, s uint8, v uint8) (uint8, uint8, uint8) {
    // https://en.wikipedia.org/wiki/HSL_and_HSV#HSV_to_RGB
    V := float64(v) / 256
    S := float64(s) / 256
    C := V * S
    H := float64(h) / (256/6)
    X := float64(C) * (1 - math.Abs(math.Mod(H, 2) - 1))
    var r, g, b float64
    switch true {
    case s == 0:
        r, g, b = 0, 0, 0
    case H <= 1:
        r, g, b = C, X, 0
    case H <= 2:
        r, g, b = X, C, 0
    case H <= 3:
        r, g, b = 0, C, X
    case H <= 4:
        r, g, b = 0, X, C
    case H <= 5:
        r, g, b = X, 0, C
    default:
        r, g, b = C, 0, X
    }
    m := V - C
    r += m
    g += m
    b += m
    r *= 255
    g *= 255
    b *= 255
    return uint8(r), uint8(g), uint8(b)
}