1/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
2/*
3 * This file is part of the LibreOffice project.
4 *
5 * This Source Code Form is subject to the terms of the Mozilla Public
6 * License, v. 2.0. If a copy of the MPL was not distributed with this
7 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
8 */
9
10#version 120
11
12uniform int       i_nColors;
13uniform sampler1D t_colorArray4d;
14uniform sampler1D t_stopArray1d;
15uniform mat3x2    m_transform;
16varying vec2      v_textureCoords2d;
17
18int max(int x, int y)
19{
20    if(x > y)
21        return x;
22    return y;
23}
24
25int findBucket(float t)
26{
27    int nMinBucket=0;
28    while( nMinBucket < i_nColors &&
29            texture1D(t_stopArray1d, nMinBucket).s < t )
30        ++nMinBucket;
31    return max(nMinBucket-1,0);
32}
33
34void main(void)
35{
36    float fAlpha =
37        clamp( (m_transform * vec3(v_textureCoords2d,1)).s,
38                0.0, 1.0 );
39
40    int nMinBucket = findBucket( fAlpha );
41
42    float fLerp =
43        (fAlpha-texture1D(t_stopArray1d, nMinBucket).s) /
44        (texture1D(t_stopArray1d, nMinBucket+1).s -
45         texture1D(t_stopArray1d, nMinBucket).s);
46
47    gl_FragColor = mix(texture1D(t_colorArray4d, nMinBucket),
48            texture1D(t_colorArray4d, nMinBucket+1),
49            fLerp);
50}
51
52/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
53