70 lines
1.9 KiB
C++
70 lines
1.9 KiB
C++
/*
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* A library for avr microcontrollers to control WS2812 leds
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*
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* Copyright (C) 2016 Markus Schmidl
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*
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* This program is free software; you can redistribute it and/or modify it under the terms of the
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* GNU General Public License as published by the Free Software Foundation;
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* either version 2 of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
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* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along with this program;
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* if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <math.h>
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#include "color.h"
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#include "ws2812_avr_macros.h"
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/* derived from http://fourier.eng.hmc.edu/e161/lectures/ColorProcessing/node3.html */
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void Color::hsi2rgb(float h_, float s_, float i_)
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{
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h = h_;
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s = s_;
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i = i_;
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h_ = fmod(h_, 360);
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/* convert h to radiants */
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h_ = M_PI * h_ / 180.0;
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/* clamp s and i to interval [0:1] */
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s_ = clamp_to_0_1(s_);
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i_ = clamp_to_0_1(i_);
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if (s_ == 0.0) {
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r = g = b = i_ * 255;
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} else {
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float r_, g_, b_;
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#define hsi2rgb_color1 ((1 - s_) / 3)
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#define hsi2rgb_color2 ((1 + s_ * cos(h_) / cos((M_PI / 3.0) - h_)) / 3)
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if ((h_ >= 0.0) && (h_ < 2.0 * M_PI / 3.0)) {
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b_ = hsi2rgb_color1;
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r_ = hsi2rgb_color2;
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g_ = 1 - b_ - r_;
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} else if ((h_ >= 2.0 * M_PI / 3.0) && (h_ < 4.0 * M_PI / 3.0)) {
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h_ -= 2.0 * M_PI / 3.0;
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r_ = hsi2rgb_color1;
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g_ = hsi2rgb_color2;
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b_ = 1 - r_ - g_;
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} else {
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h_ -= 4.0 * M_PI / 3.0;
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g_ = hsi2rgb_color1;
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b_ = hsi2rgb_color2;
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r_ = 1 - g_ - b_;
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}
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r_ = i_ * r_ * 255;
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g_ = i_ * g_ * 255;
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b_ = i_ * b_ * 255;
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/* clamp r, g and b to interval [0:255] */
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r = clamp_to_0_255(r_);
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g = clamp_to_0_255(g_);
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b = clamp_to_0_255(b_);
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}
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}
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