49 lines
1.4 KiB
C++
49 lines
1.4 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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/* derived form http://www.cse.usf.edu/~mshreve/rgb-to-hsi */
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void Color::rgb2hsi(uint8_t r_, uint8_t g_, uint8_t b_)
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{
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r = r_;
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g = g_;
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b = b_;
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float h_, s_, i_, sum;
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sum = (float) (r_ + g_ + b_);
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i_ = sum / 255.0;
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/* normalize rgb values */
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float n_r = (float) r_ / sum;
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float n_g = (float) g_ / sum;
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float n_b = (float) b_ / sum;
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h_ = acos(0.5 * ((n_r - n_g) + (n_r - n_b)) / sqrt(pow((n_r - n_g), 2.0) + ((n_r - n_b) * (n_g - n_b))));
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if (n_b > n_g)
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h_ = 2 * M_PI - h_;
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s_ = 1 - 3 * fmin(n_r, fmin(n_g, n_b));
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h = h_ * 180.0 / M_PI;
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s = s_;
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i = i_;
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}
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