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#ifndef lint

static char *RCSid() { return RCSid("$Id: getcolor.c,v 1.24 2006/02/21 09:14:49 mikulik Exp $"); }

#endif

/* GNUPLOT - getcolor.c */

/*[

* Petr Mikulik, December 1998 -- June 1999

* Copyright: open source as much as possible

]*/

#include "syscfg.h"

#include "stdfn.h"

#include "util.h"

#include "getcolor.h"

* This file implements all the gray to color transforms except one:

* calculate_color_from_formulae() which can be found in color.c.

* calculate_color_from_formulae() belongs logicaly into this (getcolor.c)

* file, but it can't be here due to linkage problems: gnuplot_x11

* needs a lot of code from getcolor.c but does not contain any function

* evaluation code [and does not call calculate_color_from_formulae()].

* This file is compiled twice: Once as part of gnuplot and the second

* time with -DGPLT_X11_MODE resulting in getcolor_x11.o which is linked

* into gnuplot_x11. With GPLT_X11_MODE defined this file does not

* contain code for calculating colors from gray by user defined functions.

#ifndef GPLT_X11_MODE

static int calculate_color_from_formulae __PROTO((double, rgb_color *));

#endif

static char *dbl_to_str __PROTO((double val, char *dest));

static double str_to_dbl __PROTO((char *s));

static void color_components_from_gray __PROTO((double gray, rgb_color *color));

static char *color_to_str __PROTO((rgb_color col, char *buf));

static void str_to_color __PROTO((char *buf, rgb_color *col));

static int interpolate_color_from_gray __PROTO((double, rgb_color *));

static double get_max_dev __PROTO((rgb_color *colors, int j, double limit));

static int is_extremum __PROTO((rgb_color left,rgb_color mid,rgb_color right));

static void CMY_2_RGB __PROTO((rgb_color *color));

static void CIEXYZ_2_RGB __PROTO((rgb_color *color));

static void YIQ_2_RGB __PROTO((rgb_color *color));

static void HSV_2_RGB __PROTO((rgb_color *color));

/* check if two palettes p1 and p2 differ significantly */

int

palettes_differ(t_sm_palette *p1, t_sm_palette *p2)

{

if (p1->colorMode != p2->colorMode)

return 1;

if (p1->positive != p2->positive)

return 1;

if (p1->cmodel != p2->cmodel)

return 1;

if (p1->use_maxcolors != p2->use_maxcolors)

return 1;

switch(p1->colorMode) {

case SMPAL_COLOR_MODE_NONE:

return 0; /* ?? */

case SMPAL_COLOR_MODE_GRAY:

if (fabs(p1->gamma - p2->gamma) > 1e-3)

return 1;

break;

case SMPAL_COLOR_MODE_RGB:

if (p1->colorFormulae != p2->colorFormulae)

return 1;

if (p1->formulaR != p2->formulaR)

return 1;

if (p1->formulaG != p2->formulaG)

return 1;

if (p1->formulaB != p2->formulaB)

return 1;

/* if (p1->ps_allcF != p2->ps_allcF)

return 1; */

break;

case SMPAL_COLOR_MODE_FUNCTIONS:

/* coarse check based on typed fnct definitions */

if (strcmp(p1->Afunc.definition, p2->Afunc.definition))

return 1;

if (strcmp(p1->Bfunc.definition, p2->Bfunc.definition))

return 1;

if (strcmp(p1->Cfunc.definition, p2->Cfunc.definition))

return 1;

break;

case SMPAL_COLOR_MODE_GRADIENT: {

int i=0;

if (p1->gradient_num != p2->gradient_num)

return 1;

for(i=0; i<p1->gradient_num; ++i) {

if (p1->gradient[i].pos != p2->gradient[i].pos)

return 1;

if (p1->gradient[i].col.r != p2->gradient[i].col.r)

return 1;

if (p1->gradient[i].col.g != p2->gradient[i].col.g)

return 1;

if (p1->gradient[i].col.b != p2->gradient[i].col.b)

return 1;

}

break;

} /* case GRADIENT */

} /* switch() */

return 0; /* no real difference found */

}

/* Store double value from [0,1] in 2 characters. Resolution is 6.1e-5.

* No '\n' are generated. */

static char *dbl_to_str(double val, char *dest)

{

unsigned int ival = (unsigned int) (((1 << 14) - 1) * val);

dest[0] = (ival >> 7) + 33;

dest[1] = (ival & 127) + 33;

return dest;

}

/* Reverse of dbl_to_str(): map 2 characters to double in [0,1] */

static double

str_to_dbl(char *s)

{

unsigned int ival =

(((unsigned int) (s[0] - 33) & 127) << 7)

| (unsigned int) ((s[1] - 33) & 127);

double val = ((double) ival) / ((1 << 14) - 1);

return val;

}

/* Save rgb_color to 6 characters which are no '\n'. */

static char

*color_to_str(rgb_color col, char *buf)

{

dbl_to_str(col.r, buf + 0);

dbl_to_str(col.g, buf + 2);

dbl_to_str(col.b, buf + 4);

buf[6] = 0;

return buf;

}

/* Restore rgb_color from 6 characters */

static void

str_to_color(char *buf, rgb_color *col)

{

col->r = str_to_dbl(buf + 0);

col->g = str_to_dbl(buf + 2);

col->b = str_to_dbl(buf + 4);

}

/* Store a gradient entry in 8 characters which do not contain '\n' */

char *

gradient_entry_to_str(gradient_struct *gs)

{

static char buf[20];

dbl_to_str(gs->pos, buf);

color_to_str(gs->col, buf + 2);

return buf;

}

/* Gestore gradient entry from string */

void

str_to_gradient_entry(char *s, gradient_struct *gs)

{

gs->pos = str_to_dbl(s);

str_to_color(s + 2, & (gs->col));

}

#define CONSTRAIN(x) ((x) < 0 ? 0 : ((x) > 1 ? 1 : (x)))

/* This one takes the gradient defined in sm_palette.gradient and

* returns an interpolated color for the given gray value. It

* does not matter wether RGB or HSV or whatever values are stored

* in sm_palette.gradient[i].col, they will simply be interpolated.

* Return 0 on sucess, 1 if gray outside the range covered by the

* gradient. No gamma correction is done. The user can implement

* gamma correction specifying more points.

* sm_palette.gradient[] should be sorted acording to .pos.

* Returns 1 on failure and fills color with "nearest" color.

static int

interpolate_color_from_gray(double gray, rgb_color *color)

{

int idx, maxidx;

rgb_color *col1;

rgb_color *col2;

if (gray < 0) {

color->r = sm_palette.gradient[0].col.r;

color->g = sm_palette.gradient[0].col.g;

color->b = sm_palette.gradient[0].col.b;

return 1;

}

maxidx = sm_palette.gradient_num;

if (gray > 1) {

color->r = sm_palette.gradient[maxidx-1].col.r;

color->g = sm_palette.gradient[maxidx-1].col.g;

color->b = sm_palette.gradient[maxidx-1].col.b;

return 1;

}

/* find index by bisecting */

idx = 0;

if (maxidx > 1) {

int topidx = maxidx - 1;

/* treat idx as though it is bottom index */

while (idx != topidx) {

int tmpidx = (idx + topidx) / 2;

if (sm_palette.gradient[tmpidx].pos < gray)

idx = tmpidx + 1; /* round up */

else

topidx = tmpidx;

}

col2 = & sm_palette.gradient[idx].col;

if (gray == sm_palette.gradient[idx].pos) {

/* exact hit */

color->r = col2->r;

color->g = col2->g;

color->b = col2->b;

} else {

/* linear interpolation of two colors */

double dx = sm_palette.gradient[idx].pos

- sm_palette.gradient[idx - 1].pos;

double f = (gray - sm_palette.gradient[idx-1].pos) / dx;

col1 = & sm_palette.gradient[idx - 1].col;

color->r = (col1->r + f * (col2->r - col1->r));

color->g = (col1->g + f * (col2->g - col1->g));

color->b = (col1->b + f * (col2->b - col1->b));

}

return 0;

}

#ifndef GPLT_X11_MODE

/* Fills color with the values calculated from sm_palette.[ABC]func

* The color values are clipped to [0,1] without further notice.

* Returns 0 or does an int_error() when function evaluatin failed.

* The result is not in RGB color space jet.

static int

calculate_color_from_formulae(double gray, rgb_color *color)

{

struct value v;

double a, b, c;

#define NO_CARET (-1)

(void) Gcomplex(&sm_palette.Afunc.dummy_values[0], gray, 0.0);

evaluate_at(sm_palette.Afunc.at, &v);

if (undefined)

int_error(NO_CARET,

"Undefined value first color during function evaluation");

a = real(&v);

a = CONSTRAIN(a);

(void) Gcomplex(&sm_palette.Bfunc.dummy_values[0], gray, 0.0);

evaluate_at(sm_palette.Bfunc.at, &v);

if (undefined)

int_error(NO_CARET,

"Undefined value second color during function evaluation");

b = real(&v);

b = CONSTRAIN(b);

(void) Gcomplex(&sm_palette.Cfunc.dummy_values[0], gray, 0.0);

evaluate_at(sm_palette.Cfunc.at, &v);

if (undefined)

int_error(NO_CARET,

"Undefined value third color during function evaluation");

c = real(&v);

c = CONSTRAIN(c);

color->r = a;

color->g = b;

color->b = c;

#undef NO_CARET

return 0;

}

#endif /* !GPLT_X11_MODE */

/* Map gray in [0,1] to color components according to colorMode */

static void

color_components_from_gray(double gray, rgb_color *color)

{

if (gray < 0)

gray = 0;

else if (gray > 1.0)

gray = 1.0;

switch(sm_palette.colorMode) {

case SMPAL_COLOR_MODE_GRAY:

color->r = color->g = color->b = pow(gray, 1.0/sm_palette.gamma);

return; /* all done, no color space transformation needed */

case SMPAL_COLOR_MODE_RGB:

color->r = GetColorValueFromFormula(sm_palette.formulaR, gray);

color->g = GetColorValueFromFormula(sm_palette.formulaG, gray);

color->b = GetColorValueFromFormula(sm_palette.formulaB, gray);

break;

case SMPAL_COLOR_MODE_GRADIENT:

interpolate_color_from_gray(gray, color);

break;

#ifndef GPLT_X11_MODE

case SMPAL_COLOR_MODE_FUNCTIONS:

calculate_color_from_formulae(gray, color);

break;

#endif /* !GPLT_X11_MODE */

default:

fprintf(stderr, "%s:%d ooops: Unknown colorMode '%c'.\n",

__FILE__, __LINE__, (char)(sm_palette.colorMode));

}

* Map a gray value in [0,1] to the corresponding RGB values in [0,1],

* according to the current colorMode and color space.

* Note -- November 2003: this routine has been renamed from color_from_gray()

* to rgb1_from_gray() in order to more clearly distinguish structures

* rgb_color and rgb255_color.

void

rgb1_from_gray(double gray, rgb_color *color)

{

/* get the color */

color_components_from_gray(gray, color);

if (sm_palette.colorMode == SMPAL_COLOR_MODE_GRAY)

return;

/* transform to RGB if necessary */

switch(sm_palette.cmodel) {

case C_MODEL_RGB:

break;

case C_MODEL_HSV:

HSV_2_RGB(color);

break;

case C_MODEL_CMY:

CMY_2_RGB(color);

break;

case C_MODEL_YIQ:

YIQ_2_RGB(color);

break;

case C_MODEL_XYZ:

CIEXYZ_2_RGB(color);

break;

default:

fprintf(stderr, "%s:%d ooops: Unknown color model '%c'\n",

__FILE__, __LINE__, (char)(sm_palette.cmodel));

}

* Convenience function to map R, G and B float values [0,1] to uchars [0,255].

void

rgb255_from_rgb1(rgb_color rgb1, rgb255_color *rgb255)

{

rgb255->r = (unsigned char)(255 * rgb1.r + 0.5);

rgb255->g = (unsigned char)(255 * rgb1.g + 0.5);

rgb255->b = (unsigned char)(255 * rgb1.b + 0.5);

}

* Convenience function to map gray values to R, G and B values in [0,1],

* taking care of palette maxcolors (i.e., discrete nb of colors).

void

rgb1maxcolors_from_gray(double gray, rgb_color *color)

{

if (sm_palette.use_maxcolors != 0)

gray = floor(gray * sm_palette.use_maxcolors)

/ (sm_palette.use_maxcolors-1);

rgb1_from_gray(gray, color);

}

* Convenience function to map gray values to R, G and B values in [0,255],

* taking care of palette maxcolors (i.e., discrete nb of colors).

void

rgb255maxcolors_from_gray(double gray, rgb255_color *rgb255)

{

rgb_color rgb1;

rgb1maxcolors_from_gray(gray, &rgb1);

rgb255_from_rgb1(rgb1, rgb255);

}

* Used by approximate_palette

static double

get_max_dev(rgb_color *colors, int j, double limit)

{

double max_dev = 0.0;

double rdev, gdev, bdev;

double r=colors[0].r, g=colors[0].g, b=colors[0].b;

int i;

double sr = (colors[j].r - r) / j;

double sg = (colors[j].g - g) / j;

double sb = (colors[j].b - b) / j;

for(i=1; i<j; ++i) {

double dx = i;

rdev = fabs(sr*dx + r - colors[i].r);

gdev = fabs(sg*dx + g - colors[i].g);

bdev = fabs(sb*dx + b - colors[i].b);

if(rdev > max_dev)

max_dev = rdev;

if(gdev > max_dev)

max_dev = gdev;

if(bdev > max_dev)

max_dev = bdev;

if(max_dev >= limit)

break;

}

return max_dev;

}

* Used by approximate_palette: true if one color component in mid

* is higher (or lower) than both left and right, flase other wise

static int

is_extremum(rgb_color left, rgb_color mid, rgb_color right)

{

/* mid is maximum */

if(left.r < mid.r && mid.r > right.r)

return 1;

if(left.g < mid.g && mid.g > right.g)

return 1;

if(left.b < mid.b && mid.b > right.b)

return 1;

/* mid is minimum */

if(left.r > mid.r && mid.r < right.r)

return 1;

if(left.g > mid.g && mid.g < right.g)

return 1;

if(left.b > mid.b && mid.b < right.b)

return 1;

return 0;

}

#define GROW_GRADIENT(n) do { \

if(cnt == gradient_size) { \

gradient_size += (n); \

gradient = (gradient_struct*) \

realloc(gradient, gradient_size * sizeof(gradient_struct)); \

} \

} while(0)

* This function takes a palette and constructs a gradient which can

* be used to approximate the palette by linear interpolation.

* The palette is sampled at samples+1 points equally spaced in [0,1].

* From this huge gradient a much smaler one is constructed by selecting

* just those sampling points which still do approximate the full sampled

* one well enough. allowed_deviation determines the maximum deviation

* of all color components which is still acceptable for the reduced

* gradient. Use a sufficiently large number of samples (500 to 5000).

* Please free() the returned gradient after use. samples, allowed_deviation

* and max_skip may be <=0 and useful defaults will be used.

* Most probably it's useless to approximate a gradient- or rgbformulae-

* palette. Use it to build gradients from function palettes.

gradient_struct *

approximate_palette(t_sm_palette *palette, int samples,

double allowed_deviation,

int *gradient_num)

{

int i=0, j=0;

double gray=0;

int gradient_size=50;

gradient_struct *gradient;

int colors_size=100;

rgb_color *colors;

int cnt=0;

rgb_color color;

double max_dev=0.0;

/* int maximum_j=0, extrema=0; */

/* useful defaults */

if (samples <= 0)

samples = 2000;

if (allowed_deviation <= 0)

allowed_deviation = 0.003;

gradient = (gradient_struct*)

malloc(gradient_size * sizeof(gradient_struct));

colors = (rgb_color*) malloc(colors_size * sizeof(rgb_color));

assert(gradient && colors);

/* start (gray=0.0) is needed */

cnt = 0;

color_components_from_gray(0.0, colors + 0);

gradient[0].pos = 0.0;

gradient[0].col = colors[0];

++cnt;

color_components_from_gray(1.0 / samples, colors + 1);

for(i = 0; i < samples; ++i) {

for(j = 2; i + j <= samples; ++j) {

gray = ((double) (i + j)) / samples;

if (j == colors_size) {

colors_size += 50;

colors = (rgb_color *)

realloc(colors, colors_size*sizeof(gradient_struct));

}

color_components_from_gray(gray, colors + j);

/* test for extremum */

if(is_extremum(colors[j - 2], colors[j - 1], colors[j])) {

/* fprintf(stderr,"Extremum at %g\n", gray); */

/* ++extrema; */

break;

}

/* to big deviation */

max_dev = get_max_dev(colors, j, allowed_deviation);

if(max_dev > allowed_deviation) {

/* fprintf(stderr,"Control Point at %.3g\n",gray); */

break;

}

GROW_GRADIENT(25);

gradient[cnt].pos = gray;

gradient[cnt].col = colors[j - 1];

++cnt;

/* if(j-1 > maximum_j) maximum_j = j-1; */

colors[0] = colors[j - 1];

colors[1] = colors[j];

i += j - 1;

}

color_components_from_gray(1.0, &color);

GROW_GRADIENT(1);

gradient[cnt].pos = 1.0;

gradient[cnt].col = color;

++cnt;

/***********

fprintf(stderr,

"PS interpolation table: %d samples, allowed deviation %.2f%%:\n",

samples, 100*allowed_deviation);

fprintf(stderr, " --> new size %d, %d extrema, max skip %d\n",

cnt, extrema, maximum_j);

************/

free(colors);

*gradient_num = cnt;

return gradient; /* don't forget to free() it once you'r done with it */

}

#undef GROW_GRADIENT

* Original fixed color transformations

double

GetColorValueFromFormula(int formula, double x)

{

/* the input gray x is supposed to be in interval [0,1] */

if (formula < 0) { /* negate the value for negative formula */

x = 1 - x;

formula = -formula;

}

switch (formula) {

case 0:

return 0;

case 1:

return 0.5;

case 2:

return 1;

case 3: /* x = x */

break;

case 4:

x = x * x;

break;

case 5:

x = x * x * x;

break;

case 6:

x = x * x * x * x;

break;

case 7:

x = sqrt(x);

break;

case 8:

x = sqrt(sqrt(x));

break;

case 9:

x = sin(90 * x * DEG2RAD);

break;

case 10:

x = cos(90 * x * DEG2RAD);

break;

case 11:

x = fabs(x - 0.5);

break;

case 12:

x = (2 * x - 1) * (2.0 * x - 1);

break;

case 13:

x = sin(180 * x * DEG2RAD);

break;

case 14:

x = fabs(cos(180 * x * DEG2RAD));

break;

case 15:

x = sin(360 * x * DEG2RAD);

break;

case 16:

x = cos(360 * x * DEG2RAD);

break;

case 17:

x = fabs(sin(360 * x * DEG2RAD));

break;

case 18:

x = fabs(cos(360 * x * DEG2RAD));

break;

case 19:

x = fabs(sin(720 * x * DEG2RAD));

break;

case 20:

x = fabs(cos(720 * x * DEG2RAD));

break;

case 21:

x = 3 * x;

break;

case 22:

x = 3 * x - 1;

break;

case 23:

x = 3 * x - 2;

break;

case 24:

x = fabs(3 * x - 1);

break;

case 25:

x = fabs(3 * x - 2);

break;

case 26:

x = (1.5 * x - 0.5);

break;

case 27:

x = (1.5 * x - 1);

break;

case 28:

x = fabs(1.5 * x - 0.5);

break;

case 29:

x = fabs(1.5 * x - 1);

break;

case 30:

if (x <= 0.25)

return 0;

if (x >= 0.57)

return 1;

x = x / 0.32 - 0.78125;

break;

case 31:

if (x <= 0.42)

return 0;

if (x >= 0.92)

return 1;

x = 2 * x - 0.84;

break;

case 32:

if (x <= 0.42)

x *= 4;

else

x = (x <= 0.92) ? -2 * x + 1.84 : x / 0.08 - 11.5;

break;

case 33:

x = fabs(2 * x - 0.5);

break;

case 34:

x = 2 * x;

break;

case 35:

x = 2 * x - 0.5;

break;

case 36:

x = 2 * x - 1;

break;

IMPORTANT: if any new formula is added here, then:

(1) its postscript counterpart must be added into term/post.trm,

search for "ps_math_color_formulae[]"

(2) number of colours must be incremented in color.c: variable

sm_palette, first item---search for "t_sm_palette sm_palette = "

default:

fprintf(stderr, "Fatal: undefined color formula (can be 0--%i)\n", sm_palette.colorFormulae - 1);

exit(1);

}

if (x <= 0)

return 0;

if (x >= 1)

return 1;

return x;

}

/* Implementation of pm3dGetColorValue() in the postscript way.

Notice that the description, i.e. the part after %, is important

since it is used in `show pm3d' for displaying the analytical formulae.

The postscript formulae will be expanded into lines like:

"/cF0 {pop 0} bind def\t% 0",

"/cF4 {dup mul} bind def\t% x^2",

const char *ps_math_color_formulae[] = {

/* /cF0 */ "pop 0", "0",

/* /cF1 */ "pop 0.5", "0.5",

/* /cF2 */ "pop 1", "1",

/* /cF3 */ " ", "x",

/* /cF4 */ "dup mul", "x^2",

/* /cF5 */ "dup dup mul mul", "x^3",

/* /cF6 */ "dup mul dup mul", "x^4",

/* /cF7 */ "sqrt", "sqrt(x)",

/* /cF8 */ "sqrt sqrt", "sqrt(sqrt(x))",

/* /cF9 */ "90 mul sin", "sin(90x)",

/* /cF10 */ "90 mul cos", "cos(90x)",

/* /cF11 */ "0.5 sub abs", "|x-0.5|",

/* /cF12 */ "2 mul 1 sub dup mul", "(2x-1)^2",

/* /cF13 */ "180 mul sin", "sin(180x)",

/* /cF14 */ "180 mul cos abs", "|cos(180x)|",

/* /cF15 */ "360 mul sin", "sin(360x)",

/* /cF16 */ "360 mul cos", "cos(360x)",

/* /cF17 */ "360 mul sin abs", "|sin(360x)|",

/* /cF18 */ "360 mul cos abs", "|cos(360x)|",

/* /cF19 */ "720 mul sin abs", "|sin(720x)|",

/* /cF20 */ "720 mul cos abs", "|cos(720x)|",

/* /cF21 */ "3 mul", "3x",

/* /cF22 */ "3 mul 1 sub", "3x-1",

/* /cF23 */ "3 mul 2 sub", "3x-2",

/* /cF24 */ "3 mul 1 sub abs", "|3x-1|",

/* /cF25 */ "3 mul 2 sub abs", "|3x-2|",

/* /cF26 */ "1.5 mul .5 sub", "(3x-1)/2",

/* /cF27 */ "1.5 mul 1 sub", "(3x-2)/2",

/* /cF28 */ "1.5 mul .5 sub abs", "|(3x-1)/2|",

/* /cF29 */ "1.5 mul 1 sub abs", "|(3x-2)/2|",

/* /cF30 */ "0.32 div 0.78125 sub", "x/0.32-0.78125",

/* /cF31 */ "2 mul 0.84 sub", "2*x-0.84",

/* /cF32 */ "dup 0.42 le {4 mul} {dup 0.92 le {-2 mul 1.84 add} {0.08 div 11.5 sub} ifelse} ifelse",

"4x;1;-2x+1.84;x/0.08-11.5",

/* /cF33 */ "2 mul 0.5 sub abs", "|2*x - 0.5|",

/* /cF34 */ "2 mul", "2*x",

/* /cF35 */ "2 mul 0.5 sub", "2*x - 0.5",

/* /cF36 */ "2 mul 1 sub", "2*x - 1",

"", ""};

* Color Conversion Algorithms

* taken from http://www.cs.rit.edu/~ncs/color/t_convert.html

* each color model should provide a conversion to RGB.

* RGB values are clipped to [0,1] as some colors in some

* models have no RGB value.

static void

CMY_2_RGB(rgb_color *col)

{

double c,m,y;

c = col->r;

m = col->g;

y = col->b;

col->r = CONSTRAIN(1.0 - c);

col->g = CONSTRAIN(1.0 - m);

col->b = CONSTRAIN(1.0 - y);

}

static void

CIEXYZ_2_RGB(rgb_color *col)

{

double x,y,z;

x = col->r;

y = col->g;

z = col->b;

col->r = CONSTRAIN( 1.9100 * x - 0.5338 * y - 0.2891 * z);

col->g = CONSTRAIN(-0.9844 * x + 1.9990 * y - 0.0279 * z);

col->b = CONSTRAIN( 0.0585 * x - 0.1187 * y - 0.9017 * z);

}

static void

YIQ_2_RGB(rgb_color *col)

{

double y,i,q;

y = col->r;

i = col->g;

q = col->b;

col->r = CONSTRAIN(y - 0.956 * i + 0.621 * q);

col->g = CONSTRAIN(y - 0.272 * i - 0.647 * q);

col->b = CONSTRAIN(y - 1.105 * i - 1.702 * q);

}

static void

HSV_2_RGB(rgb_color *col)

{

double h,s,v, f,p,q,t;

int i;

h = col->r;

s = col->g;

v = col->b;

if (s == 0) { /* achromatic (gray) */

col->r = col->g = col->b = v;

return;

}

h *= 6.; /* h range in gnuplot is [0,1] and not the usual [0,360] */

i = floor(h);

f = h - i;

p = v * (1.0 - s);

q = v * (1.0 - s*f);

t = v * (1.0 - s*(1.0-f));

switch(i % 6) {

case 0:

col->r = v;

col->g = t;

col->b = p;

break;

case 1:

col->r = q;

col->g = v;

col->b = p;

break;

case 2:

col->r = p;

col->g = v;

col->b = t;

break;

case 3:

col->r = p;

col->g = q;

col->b = v;

break;

case 4:

col->r = t;

col->g = p;

col->b = v;

break;

default:

col->r = v;

col->g = p;

col->b = q;

break;

}

#undef CONSTRAIN

/* eof getcolor.c */

gnuplot-old/src/getcolor.c at gnuplot-4-4-alpha · gnuplot/gnuplot-old · GitHub

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