forked from bartvdbraak/blender
335ffb0ff3
Contrast helps to adjust IBL (HDR images used for background lighting). Note: In the UI we are caling it Bright instead of Brightness. This copy what Blender composite is doing. Note2: the algorithm we are using produces pure black when contrast is 100. I'm not a fan of that, but it's a division by zero. I would like to look at other algorithms (what gimp does for example). But that would be only after 2.62.
51 lines
1.3 KiB
Plaintext
51 lines
1.3 KiB
Plaintext
/*
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* Copyright 2011, Blender Foundation.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* 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,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* 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
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#include "stdosl.h"
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shader node_brightness(
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color ColorIn = color(0.8, 0.8, 0.8),
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float Bright = 0.0,
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float Contrast = 0.0,
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output ColorOut = color(0.8, 0.8, 0.8)
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{
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float delta = Contrast * (1.0/200.0);
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float a = 1.0 - delta * 2.0;
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float b;
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Bright *= 1.0/100.0;
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/*
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* The algorithm is by Werner D. Streidt
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* (http://visca.com/ffactory/archives/5-99/msg00021.html)
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* Extracted of OpenCV demhist.c
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*/
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if (Contrast > 0.0) {
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a = (a < 0.0 ? 1.0/a : 0.0);
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b = a * (Brightness - delta);
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}
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else {
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delta *= -1.0;
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b = a * (Brightness + delta);
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}
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ColorOut = a * ColorIn + b;
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}
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