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/****************************************************************************
**
** Copyright (C) 2023 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtQuick module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/
uniform sampler2D gradTabTexture;
uniform lowp float opacity;
uniform highp vec2 focalToCenter;
uniform highp float centerRadius;
uniform highp float focalRadius;
varying highp vec2 coord;
void main()
{
highp float rd = centerRadius - focalRadius;
highp float b = 2.0 * (rd * focalRadius + dot(coord, focalToCenter));
highp float fmp2_m_radius2 = -focalToCenter.x * focalToCenter.x - focalToCenter.y * focalToCenter.y + rd * rd;
highp float inverse_2_fmp2_m_radius2 = 1.0 / (2.0 * fmp2_m_radius2);
highp float det = b * b - 4.0 * fmp2_m_radius2 * ((focalRadius * focalRadius) - dot(coord, coord));
lowp vec4 result = vec4(0.0);
if (det >= 0.0) {
highp float detSqrt = sqrt(det);
highp float w = max((-b - detSqrt) * inverse_2_fmp2_m_radius2, (-b + detSqrt) * inverse_2_fmp2_m_radius2);
if (focalRadius + w * (centerRadius - focalRadius) >= 0.0)
result = texture2D(gradTabTexture, vec2(w, 0.5)) * opacity;
}
gl_FragColor = result;
}
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