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[wpilib] Improve Color FromHSV (#4439)

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This commit is contained in:
Oliver W
2022-09-29 14:33:33 +10:00
committed by GitHub
parent 4ddb8aa0dd
commit abbfe244b5
2 changed files with 71 additions and 30 deletions
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50
wpilibc/src/main/native/include/frc/util/Color.h
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@@ -741,7 +741,7 @@ class Color {
constexpr Color() = default;
/**
* Constructs a Color.
* Constructs a Color from doubles (0-1).
*
* @param r Red value (0-1)
* @param g Green value (0-1)
@@ -752,39 +752,59 @@ class Color {
green(roundAndClamp(g)),
blue(roundAndClamp(b)) {}
/**
* Constructs a Color from ints (0-255).
*
* @param r Red value (0-255)
* @param g Green value (0-255)
* @param b Blue value (0-255)
*/
constexpr Color(int r, int g, int b)
: Color(r / 255.0, g / 255.0, b / 255.0) {}
/**
* Creates a Color from HSV values.
*
* @param h The h value [0-180]
* @param h The h value [0-180)
* @param s The s value [0-255]
* @param v The v value [0-255]
* @return The color
*/
static constexpr Color FromHSV(int h, int s, int v) {
if (s == 0) {
return {v / 255.0, v / 255.0, v / 255.0};
}
// Loosely based on
// https://en.wikipedia.org/wiki/HSL_and_HSV#HSV_to_RGB
// The hue range is split into 60 degree regions where in each region there
// is one rgb component at a low value (m), one at a high value (v) and one
// that changes (X) from low to high (X+m) or high to low (v-X)
// Difference between highest and lowest value of any rgb component
int chroma = (s * v) >> 8;
// Beacuse hue is 0-180 rather than 0-360 use 30 not 60
int region = h / 30;
int remainder = (h - (region * 30)) * 6;
int p = (v * (255 - s)) >> 8;
int q = (v * (255 - ((s * remainder) >> 8))) >> 8;
int t = (v * (255 - ((s * (255 - remainder)) >> 8))) >> 8;
// Remainder converted from 0-30 to roughly 0-255
int remainder = (h - (region * 30)) * 9;
// Value of the lowest rgb component
int m = v - chroma;
// Goes from 0 to chroma as hue increases
int X = (chroma * remainder) >> 8;
switch (region) {
case 0:
return Color(v / 255.0, t / 255.0, p / 255.0);
return Color(v, X + m, m);
case 1:
return Color(q / 255.0, v / 255.0, p / 255.0);
return Color(v - X, v, m);
case 2:
return Color(p / 255.0, v / 255.0, t / 255.0);
return Color(m, v, X + m);
case 3:
return Color(p / 255.0, q / 255.0, v / 255.0);
return Color(m, v - X, v);
case 4:
return Color(t / 255.0, p / 255.0, v / 255.0);
return Color(X + m, m, v);
default:
return Color(v / 255.0, p / 255.0, q / 255.0);
return Color(v, m, v - X);
}
}