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/*************************************************************************
* Copyright (C) 2009-2010 Tavian Barnes <tavianator@tavianator.com> *
* *
* This file is part of The Dimension Library. *
* *
* The Dimension Library is free software; you can redistribute it and/ *
* or modify it under the terms of the GNU Lesser General Public License *
* as published by the Free Software Foundation; either version 3 of the *
* License, or (at your option) any later version. *
* *
* The Dimension Library 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 *
* Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public *
* License along with this program. If not, see *
* <http://www.gnu.org/licenses/>. *
*************************************************************************/
/**
* @file
* Color handling.
*/
#include "dimension.h"
/* Standard colors */
const dmnsn_color dmnsn_black = {
.R = 0.0,
.G = 0.0,
.B = 0.0,
.trans = 0.0,
.filter = 0.0,
};
const dmnsn_color dmnsn_white = {
.R = 1.0,
.G = 1.0,
.B = 1.0,
.trans = 0.0,
.filter = 0.0,
};
const dmnsn_color dmnsn_clear = {
.R = 0.0,
.G = 0.0,
.B = 0.0,
.trans = 1.0,
.filter = 0.0,
};
const dmnsn_color dmnsn_red = {
.R = 1.0,
.G = 0.0,
.B = 0.0,
.trans = 0.0,
.filter = 0.0,
};
const dmnsn_color dmnsn_green = {
.R = 0.0,
.G = 1.0,
.B = 0.0,
.trans = 0.0,
.filter = 0.0,
};
const dmnsn_color dmnsn_blue = {
.R = 0.0,
.G = 0.0,
.B = 1.0,
.trans = 0.0,
.filter = 0.0,
};
const dmnsn_color dmnsn_magenta = {
.R = 1.0,
.G = 0.0,
.B = 1.0,
.trans = 0.0,
.filter = 0.0,
};
const dmnsn_color dmnsn_orange = {
.R = 1.0,
.G = 0.21404114048223255,
.B = 0.0,
.trans = 0.0,
.filter = 0.0,
};
const dmnsn_color dmnsn_yellow = {
.R = 1.0,
.G = 1.0,
.B = 0.0,
.trans = 0.0,
.filter = 0.0,
};
const dmnsn_color dmnsn_cyan = {
.R = 0.0,
.G = 1.0,
.B = 1.0,
.filter = 0.0,
.trans = 0.0,
};
/** Inverse function of sRGB's `C' function, for the reverse conversion. */
static double
dmnsn_sRGB_C_inv(double CsRGB)
{
/*
* If C represents R, G, and B, then the Clinear values are now found as
* follows:
*
* { Csrgb/12.92, Csrgb <= 0.04045
* Clinear = { 1/2.4
* { ((Csrgb + 0.055)/1.055) , Csrgb > 0.04045
*/
if (CsRGB == 1.0) {
return 1.0; /* Map 1.0 to 1.0 instead of 0.9999999999999999 */
} else if (CsRGB <= 0.040449936) {
return CsRGB/12.92;
} else {
return pow((CsRGB + 0.055)/1.055, 2.4);
}
}
/* Convert from sRGB space */
dmnsn_color
dmnsn_color_from_sRGB(dmnsn_color color)
{
dmnsn_color ret = {
.R = dmnsn_sRGB_C_inv(color.R),
.G = dmnsn_sRGB_C_inv(color.G),
.B = dmnsn_sRGB_C_inv(color.B),
.trans = color.trans,
.filter = color.filter,
};
return ret;
}
/** sRGB's `C' function. */
static double
dmnsn_sRGB_C(double Clinear)
{
/*
* If C represents R, G, and B, then the sRGB values are now found as follows:
*
* { 12.92*Clinear, Clinear <= 0.0031308
* Csrgb = { 1/2.4
* { (1.055)*Clinear - 0.055, Clinear > 0.0031308
*/
if (Clinear == 1.0) {
return 1.0; /* Map 1.0 to 1.0 instead of 0.9999999999999999 */
} else if (Clinear <= 0.0031308) {
return 12.92*Clinear;
} else {
return 1.055*pow(Clinear, 1.0/2.4) - 0.055;
}
}
/* Convert to sRGB space */
dmnsn_color
dmnsn_color_to_sRGB(dmnsn_color color)
{
dmnsn_color ret = {
.R = dmnsn_sRGB_C(color.R),
.G = dmnsn_sRGB_C(color.G),
.B = dmnsn_sRGB_C(color.B),
.trans = color.trans,
.filter = color.filter,
};
return ret;
}
/* Greyscale color intensity */
double
dmnsn_color_intensity(dmnsn_color color)
{
return 0.2126198631048975*color.R + 0.7151387878413206*color.G
+ 0.0721499433963131*color.B;
}
/* Add two colors */
dmnsn_color
dmnsn_color_add(dmnsn_color c1, dmnsn_color c2)
{
dmnsn_color ret = dmnsn_new_color(c1.R + c2.R, c1.G + c2.G, c1.B + c2.B);
/* Switch into absolute filter and transmittance space */
double n1 = dmnsn_color_intensity(c1), n2 = dmnsn_color_intensity(c2);
double f1 = c1.filter*c1.trans, f2 = c2.filter*c2.trans;
double t1 = c1.trans - f1, t2 = c2.trans - f2;
double f = 0.0;
if (n1 + n2 >= dmnsn_epsilon)
f = (n1*f1 + n2*f2)/(n1 + n2);
double t = t1 + t2;
/* Switch back */
ret.trans = f + t;
if (ret.trans >= dmnsn_epsilon)
ret.filter = f/ret.trans;
return ret;
}
/* Multiply a color by a scalar */
dmnsn_color
dmnsn_color_mul(double n, dmnsn_color color)
{
color.R *= n;
color.G *= n;
color.B *= n;
return color;
}
/* For n in [0, 1] get the color in a gradient between c1 and c2 */
dmnsn_color
dmnsn_color_gradient(dmnsn_color c1, dmnsn_color c2, double n)
{
dmnsn_color ret = dmnsn_new_color(
n*(c2.R - c1.R) + c1.R,
n*(c2.G - c1.G) + c1.G,
n*(c2.B - c1.B) + c1.B
);
/* Switch into absolute filter and transmittance space */
double f1 = c1.filter*c1.trans, f2 = c2.filter*c2.trans;
double t1 = c1.trans - f1, t2 = c2.trans - f2;
double f = n*(f2 - f1) + f1;
double t = n*(t2 - t1) + t1;
/* Switch back */
ret.trans = f + t;
ret.filter = 0.0;
if (ret.trans >= dmnsn_epsilon)
ret.filter = f/ret.trans;
return ret;
}
/* Filters `light' through `filter' */
dmnsn_color
dmnsn_filter_light(dmnsn_color light, dmnsn_color filter)
{
dmnsn_color transmitted = dmnsn_color_mul(
(1.0 - filter.filter)*filter.trans,
light
);
dmnsn_color filtered = dmnsn_color_mul(
filter.filter*filter.trans,
dmnsn_color_illuminate(filter, light)
);
dmnsn_color ret = dmnsn_color_add(transmitted, filtered);
/* Switch into absolute filter and transmittance space */
double lf = light.filter*light.trans, ff = filter.filter*filter.trans;
double lt = light.trans - lf, ft = filter.trans - ff;
double f = lf*(dmnsn_color_intensity(filtered) + ft) + lt*ff;
double t = ft*lt;
/* Switch back */
ret.trans = f + t;
ret.filter = 0.0;
if (ret.trans >= dmnsn_epsilon)
ret.filter = f/ret.trans;
return ret;
}
/* Adds the background contribution, `filtered', to `filter' */
dmnsn_color
dmnsn_apply_translucency(dmnsn_color filtered, dmnsn_color filter)
{
dmnsn_color ret = dmnsn_color_add(
dmnsn_color_mul(1.0 - filter.trans, filter),
filtered
);
ret.trans = filtered.trans;
ret.filter = filtered.filter;
return ret;
}
/* Adds the background contribution of `color' to `filter' */
dmnsn_color
dmnsn_apply_filter(dmnsn_color color, dmnsn_color filter)
{
return dmnsn_apply_translucency(dmnsn_filter_light(color, filter), filter);
}
/* Remove the filter channel */
dmnsn_color
dmnsn_remove_filter(dmnsn_color color)
{
double intensity = dmnsn_color_intensity(color);
double newtrans = (1.0 - (1.0 - intensity)*color.filter)*color.trans;
if (1.0 - newtrans >= dmnsn_epsilon)
color = dmnsn_color_mul((1.0 - color.trans)/(1.0 - newtrans), color);
color.trans = newtrans;
color.filter = 0.0;
return color;
}
/* Illuminates `color' with `light' */
dmnsn_color
dmnsn_color_illuminate(dmnsn_color light, dmnsn_color color)
{
return dmnsn_new_color5(light.R*color.R, light.G*color.G, light.B*color.B,
color.filter, color.trans);
}
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