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October 20, 2018 19:25
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Proper Conversion of HSL color to RGB
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/* | |
HSL to RGB | |
Compile with: gcc hsl_to_rgb.c -lm -o hsl_to_rgb | |
Attributions to: cburn11, https://forum.level1techs.com/u/cburn11 | |
*/ | |
#include <stdlib.h> | |
#include <stdio.h> | |
#include <math.h> | |
#include <stdint.h> | |
struct hsl | |
{ | |
int h; | |
float s; | |
float l; | |
}; | |
struct rgb | |
{ | |
uint8_t r; | |
uint8_t g; | |
uint8_t b; | |
}; | |
float hue_to_color(float p, float q, float t) | |
{ | |
if(t < 0) ++t; | |
if(t > 1) --t; | |
if(1.0f / 6.0f > t) return p + (q - p) * 6 * t; | |
if(0.5f > t) return q; | |
if(2.0f / 3.0f > t) return p + (q - p) * (2.0f / 3.0f - t) * 6; | |
return p; | |
} | |
struct rgb hsl_to_rgb(int hdeg, float s, float l) | |
{ | |
float h = abs(hdeg) % 360 / 360.0f; | |
float r = 0.f, g = 0.f, b = 0.f; | |
struct rgb rgb; | |
if(0 == s) | |
{ | |
r = g = b = l; | |
} | |
else | |
{ | |
float q = l < 0.5f ? l * (1 + s) : l + s - l * s; | |
float p = 2 * l - q; | |
r = hue_to_color(p, q, h + 1.0f / 3.0f); | |
g = hue_to_color(p, q, h); | |
b = hue_to_color(p, q, h - 1.0f / 3.0f); | |
} | |
rgb.r = round(r * 0xff); rgb.g = round(g * 0xff); rgb.b = round(b * 0xff); | |
return rgb; | |
} | |
int main(void) | |
{ | |
struct hsl input = {123, 0.3f, 0.4f}; | |
struct rgb output = hsl_to_rgb(input.h, input.s, input.l); | |
printf("\nConverted hsl(%d°, %.2f%%, %.2f%%) to rgb(%d, %d, %d)\n\n", | |
input.h, input.s * 100, input.l * 100, | |
output.r, output.g, output.b); | |
return 0; | |
} |
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