blob: a8c73d6b80cc1716d96a18226a646156eb6f645b (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
|
/* -*- 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/.
*/
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 chanel only
vec4 result_color = color;
result_color.a = result_color.a * alpha;
gl_FragColor = result_color;
}
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
|
