forked from bartvdbraak/blender
58 lines
1.7 KiB
C
58 lines
1.7 KiB
C
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/*
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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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CCL_NAMESPACE_BEGIN
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__device void svm_node_brightness(ShaderData *sd, float *stack, uint in_color, uint out_color, uint node)
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{
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uint bright_offset, contrast_offset;
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float3 color = stack_load_float3(stack, in_color);
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decode_node_uchar4(node, &bright_offset, &contrast_offset, NULL, NULL);
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float brightness = stack_load_float(stack, bright_offset);
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float contrast = stack_load_float(stack, contrast_offset);
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brightness *= 1.0f/100.0f;
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float delta = contrast * (1.0f/200.0f);
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float a = 1.0f - delta * 2.0f;
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float b;
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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 > 0.0f) {
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a = (a > 0.0f? (1.0f / a): 0.0f);
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b = a * (brightness - delta);
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}
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else {
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delta *= -1.0f;
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b = a * (brightness + delta);
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}
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color.x = a*color.x + b;
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color.y = a*color.y + b;
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color.z = a*color.z + b;
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if (stack_valid(out_color))
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stack_store_float3(stack, out_color, color);
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}
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CCL_NAMESPACE_END
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