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