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/*************************************************************************
* Copyright (C) 2009-2011 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
* Colors.
*/
#include <stdbool.h>
/** A color value. */
typedef struct {
double R; /**< Red component. */
double G; /**< Green component. */
double B; /**< Blue component. */
} dmnsn_color;
/** A standard format string for colors. */
#define DMNSN_COLOR_FORMAT "Color<%g, %g, %g>"
/** The appropriate arguements to printf() a color. */
#define DMNSN_COLOR_PRINTF(c) (c).R, (c).G, (c).B
/** Construct a new color. */
DMNSN_INLINE dmnsn_color
dmnsn_new_color(double R, double G, double B)
{
dmnsn_color ret = { R, G, B };
return ret;
}
/** Apply sRGB gamma */
DMNSN_INLINE double
dmnsn_sRGB_gamma(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 1.055*pow(Clinear, 1.0/2.4) - 0.055;
} else {
return 12.92*Clinear;
}
}
/** Convert to sRGB space. */
DMNSN_INLINE dmnsn_color
dmnsn_color_to_sRGB(dmnsn_color color)
{
return dmnsn_new_color(
dmnsn_sRGB_gamma(color.R),
dmnsn_sRGB_gamma(color.G),
dmnsn_sRGB_gamma(color.B)
);
}
/** Remove sRGB gamma */
DMNSN_INLINE double
dmnsn_sRGB_inverse_gamma(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_INLINE dmnsn_color
dmnsn_color_from_sRGB(dmnsn_color color)
{
return dmnsn_new_color(
dmnsn_sRGB_inverse_gamma(color.R),
dmnsn_sRGB_inverse_gamma(color.G),
dmnsn_sRGB_inverse_gamma(color.B)
);
}
/** Greyscale color intensity. */
DMNSN_INLINE double
dmnsn_color_intensity(dmnsn_color color)
{
return 0.2126*color.R + 0.7152*color.G + 0.0722*color.B;
}
/** Add two colors together. */
DMNSN_INLINE dmnsn_color
dmnsn_color_add(dmnsn_color lhs, dmnsn_color rhs)
{
return dmnsn_new_color(lhs.R + rhs.R, lhs.G + rhs.G, lhs.B + rhs.B);
}
/** Subtract two colors. */
DMNSN_INLINE dmnsn_color
dmnsn_color_sub(dmnsn_color lhs, dmnsn_color rhs)
{
return dmnsn_new_color(lhs.R - rhs.R, lhs.G - rhs.G, lhs.B - rhs.B);
}
/** Scale a color's intensity. */
DMNSN_INLINE dmnsn_color
dmnsn_color_mul(double n, dmnsn_color color)
{
return dmnsn_new_color(n*color.R, n*color.G, n*color.B);
}
/** Return the color at \p n on a gradient from \p c1 at 0 to \p c2 at 1. */
DMNSN_INLINE dmnsn_color
dmnsn_color_gradient(dmnsn_color c1, dmnsn_color c2, double n)
{
return dmnsn_new_color(
n*(c2.R - c1.R) + c1.R,
n*(c2.G - c1.G) + c1.G,
n*(c2.B - c1.B) + c1.B
);
}
/** Illuminate \p color with \p light. */
DMNSN_INLINE dmnsn_color
dmnsn_color_illuminate(dmnsn_color light, dmnsn_color color)
{
return dmnsn_new_color(light.R*color.R, light.G*color.G, light.B*color.B);
}
/** Saturate the color components to [0.0, 1.0]. */
DMNSN_INLINE dmnsn_color
dmnsn_color_saturate(dmnsn_color color)
{
color.R = dmnsn_min(dmnsn_max(color.R, 0.0), 1.0);
color.G = dmnsn_min(dmnsn_max(color.G, 0.0), 1.0);
color.B = dmnsn_min(dmnsn_max(color.B, 0.0), 1.0);
return color;
}
/** Return whether a color contains any NaN components. */
DMNSN_INLINE bool
dmnsn_color_isnan(dmnsn_color color)
{
return isnan(color.R) || isnan(color.G) || isnan(color.B);
}
/* Standard colors */
/** Black. */
#define dmnsn_black dmnsn_new_color(0.0, 0.0, 0.0)
/** White. */
#define dmnsn_white dmnsn_new_color(1.0, 1.0, 1.0)
/** Red. */
#define dmnsn_red dmnsn_new_color(1.0, 0.0, 0.0)
/** Green. */
#define dmnsn_green dmnsn_new_color(0.0, 1.0, 0.0)
/** Blue. */
#define dmnsn_blue dmnsn_new_color(0.0, 0.0, 1.0)
/** Magenta. */
#define dmnsn_magenta dmnsn_new_color(1.0, 0.0, 1.0)
/** Orange. */
#define dmnsn_orange dmnsn_new_color(1.0, 0.21404114048223255, 0.0)
/** Yellow. */
#define dmnsn_yellow dmnsn_new_color(1.0, 1.0, 0.0)
/** Cyan. */
#define dmnsn_cyan dmnsn_new_color(0.0, 1.0, 1.0)
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