48 lines
1.4 KiB
GLSL
48 lines
1.4 KiB
GLSL
/* -*- 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 120
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uniform int i_nColors;
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uniform sampler1D t_colorArray4d;
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uniform sampler1D t_stopArray1d;
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uniform mat3x2 m_transform;
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varying vec2 v_textureCoords2d;
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const vec2 v_center2d = vec2(0,0);
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int findBucket(float t)
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{
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int nMinBucket=0;
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while( nMinBucket < i_nColors &&
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texture1D(t_stopArray1d, nMinBucket).s < t )
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++nMinBucket;
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return max(nMinBucket-1,0);
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}
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void main(void)
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{
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const float fAlpha =
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clamp( 1.0 - distance(
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vec2( m_transform * vec3(v_textureCoords2d,1)),
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v_center2d),
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0.0, 1.0 );
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const int nMinBucket=findBucket( fAlpha );
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const float fLerp =
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(fAlpha-texture1D(t_stopArray1d, nMinBucket).s) /
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(texture1D(t_stopArray1d, nMinBucket+1).s -
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texture1D(t_stopArray1d, nMinBucket).s);
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gl_FragColor = mix(texture1D(t_colorArray4d, nMinBucket),
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texture1D(t_colorArray4d, nMinBucket+1),
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fLerp);
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}
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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