39 lines
1.1 KiB
Java
39 lines
1.1 KiB
Java
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*/
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#version 130
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varying float fade_factor; // 0->1 fade factor used for AA
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uniform vec4 color;
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uniform float line_width;
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uniform float feather;
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void main()
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{
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float start = (line_width / 2.0) - feather; // where we start to apply alpha
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float end = (line_width / 2.0) + feather; // where we end to apply alpha
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// Calculate the multiplier so we can transform the 0->1 fade factor
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// to take feather and line width into account.
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float multiplied = 1.0 / (1.0 - (start / end));
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float dist = (1.0 - abs(fade_factor)) * multiplied;
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float alpha = clamp(dist, 0.0, 1.0);
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// modify the alpha channel only
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vec4 result_color = color;
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result_color.a = result_color.a * alpha;
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gl_FragColor = result_color;
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}
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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