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/*
* Color_Utils.cc -- Functions for manipulating color densities
* These functions are not normally available to users.
*
* This file is part of ePiX, a C++ library for creating high-quality
* figures in LaTeX
*
* Version 1.1.17
*
* Last Change: September 14, 2007
*/
/*
* Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006
* Andrew D. Hwang <rot 13 nujnat at zngupf dot ubylpebff dot rqh>
* Department of Mathematics and Computer Science
* College of the Holy Cross
* Worcester, MA, 01610-2395, USA
*
*/
/*
* ePiX is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* ePiX 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 General Public
* License for more details.
*
* You should have received a copy of the GNU General Public License
* along with ePiX; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <sstream>
#include <cmath>
#include "Color_Utils.h"
namespace ePiX {
// Magic number: 8-bits per color channel
const int COLORS(0xFF);
// Force double to [0,1]
double clip_to_unit(double t)
{
if (t < 0) return 0;
else if (t > 1) return 1;
else return t;
}
double rd(double arg) // may assume arg in [0,1]
{
return floor(COLORS*arg)/COLORS; // round down to nearest 8-bit
}
// represent a double in [0,1] by an 8-bit hex string
std::string dtohex(double arg) // assumes arg>0
{
using std::ios_base;
int dens((int) floor(arg*COLORS));
std::ostringstream value;
value.setf(ios_base::hex, ios_base::basefield);
if (dens <= 0xF) // pad
value << "0";
value << dens;
return value.str();
}
// saw2th:R -> [-2,2] is (1) a sawtooth function; (2) the identity on [-2,2]
double saw2th(double x)
{
return x - 4*floor((x+2)/4);
}
/*
* clippy(x):
* 1.... ____ if (x >= 0)
* .\ /. . return x <= 1 ? x : 1;
* . \ / . .
* 0......\____/ . . else
* -2 -1 0 1 2 --> x return x >= -1 ? 0 : -1-x;
*/
double clippy(double x)
{
x = saw2th(x);
return (x >= 0) ? ( x <= 1 ? x : 1 ) : ( x >= -1 ? 0 : -1-x );
}
double make_r(double r, double g, double b)
{
return clip_to_unit(clippy( r) + clippy(-g) + clippy(-b));
}
double make_g(double r, double g, double b)
{
return clip_to_unit(clippy(-r) + clippy( g) + clippy(-b));
}
double make_b(double r, double g, double b)
{
return clip_to_unit(clippy(-r) + clippy(-g) + clippy( b));
}
} // end of namespace
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