Modified /indra/llmath/v3color.h color retrieve function (https://gist.github.com/Makopo/5562402) for standalone use. $ ./rgb_to_float 7F194C STRING = 7F194C, R = 0.498039, G = 0.098039, B = 0.298039 $ ./float_to_rgb .5 .1 .3 RGB = 7F194C

float_to_rgb.c

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char const *argv[])
{
  long red = atof(argv[1])*255.f; // RED
	long green = atof(argv[2])*255.f; // GREEN
	long blue = atof(argv[3])*255.f; // BLUE

	printf("RGB = %02lX%02lX%02lX\n", red, green, blue);

	return 0;
}

rgb_to_float.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int main(int argc, char const *argv[])
{
  char tempstr[7];
	strncpy(tempstr,argv[1],6);		/* Flawfinder: ignore */
	tempstr[6] = '\0';
	float blue = (float)strtol(&tempstr[4],NULL,16)/255.f; // BLUE
	tempstr[4] = '\0';
	float green = (float)strtol(&tempstr[2],NULL,16)/255.f; // GREEN
	tempstr[2] = '\0';
	float red = (float)strtol(&tempstr[0],NULL,16)/255.f; // RED

	printf("STRING = %s, R = %f, G = %f, B = %f\n", argv[1], red, green, blue);

	return 0;
}