diff options
author | Norbert Preining <norbert@preining.info> | 2019-09-02 13:46:59 +0900 |
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committer | Norbert Preining <norbert@preining.info> | 2019-09-02 13:46:59 +0900 |
commit | e0c6872cf40896c7be36b11dcc744620f10adf1d (patch) | |
tree | 60335e10d2f4354b0674ec22d7b53f0f8abee672 /graphics/epix/Color_Utils.cc |
Initial commit
Diffstat (limited to 'graphics/epix/Color_Utils.cc')
-rw-r--r-- | graphics/epix/Color_Utils.cc | 113 |
1 files changed, 113 insertions, 0 deletions
diff --git a/graphics/epix/Color_Utils.cc b/graphics/epix/Color_Utils.cc new file mode 100644 index 0000000000..0045aafcc3 --- /dev/null +++ b/graphics/epix/Color_Utils.cc @@ -0,0 +1,113 @@ +/* + * 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., + * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ +#include <sstream> +#include <cmath> + +// #include "constants.h" +// #include "functions.h" + +#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 |