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/****************************************************************************
**
** Copyright (C) 2014 Klaralvdalens Datakonsult AB (KDAB).
** Copyright (C) 2016 The Qt Company Ltd and/or its subsidiary(-ies).
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt3D 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.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qalphacoverage.h"
#include "qrenderstate_p.h"

QT_BEGIN_NAMESPACE

namespace Qt3DRender {

/*!
    \class Qt3DRender::QAlphaCoverage
    \since 5.7
    \ingroup renderstates
    \inmodule Qt3DRender
    \brief Enable alpha-to-coverage multisampling mode.

    A Qt3DRender::QAlphaCoverage class enables alpha-to-coverage multisampling mode.
    When enabled, the fragment alpha value is used as a coverage for the sample
    and combined with fragment coverage value. Qt3DRender::QAlphaCoverage does
    nothing if multisampling is disabled. Alpha-to-coverage is most useful when
    order independent blending is required, for example when rendering leaves,
    grass and other rich vegetation.

    It can be added to a QRenderPass by calling QRenderPass::addRenderState():

    \code
    QRenderPass *renderPass = new QRenderPass();

    // Create a alpha coverage render state
    QAlphaCoverage *alphaCoverage = new QAlphaCoverage();
    QMultiSampleAntiAliasing *multiSampleAntialiasing = new QMultiSampleAntiAliasing();

    // Add the render states to the render pass
    renderPass->addRenderState(alphaCoverage);
    renderPass->addRenderState(multiSampleAntialiasing);
    \endcode

    Or to a QRenderStateSet by calling QRenderStateSet::addRenderState():

    \code
    QRenderStateSet *renderStateSet = new QRenderStateSet();

    // Create a alpha coverage render state
    QAlphaCoverage *alphaCoverage = new QAlphaCoverage();
    QMultiSampleAntiAliasing *multiSampleAntialiasing = new QMultiSampleAntiAliasing();

    // Add the render states to the render state set
    renderStateSet->addRenderState(alphaCoverage);
    renderStateSet->addRenderState(multiSampleAntialiasing);
    \endcode

    \sa Qt3DRender::QMultiSampleAntiAliasing
 */

/*!
    \qmltype AlphaCoverage
    \since 5.7
    \ingroup renderstates
    \inqmlmodule Qt3D.Render
    \instantiates Qt3DRender::QAlphaCoverage
    \inherits RenderState
    \brief Enable alpha-to-coverage multisampling mode.

    An AlphaCoverage type enables alpha-to-coverage multisampling mode.
    When enabled, the fragment alpha value is used as a coverage for the sample
    and combined with fragment coverage value. AlphaCoverage does nothing if
    multisampling is disabled. Alpha-to-coverage is most useful when
    order independent blending is required, for example when rendering leaves,
    grass and other rich vegetation.

    It can be added to a RenderPass:

    \qml
    RenderPass {
        shaderProgram: ShaderProgram {
            // ...
        }
        renderStates: [
            AlphaCoverage {},
            MultiSampleAntiAliasing {}
        ]
    }
    \endqml

    Or to a RenderStateSet:

    \qml
    RenderStateSet {
        renderStates: [
            AlphaCoverage {},
            MultiSampleAntiAliasing {}
        ]
    }
    \endqml

    \sa MultiSampleAntiAliasing
 */

class QAlphaCoveragePrivate : public QRenderStatePrivate
{
public :
    QAlphaCoveragePrivate()
        : QRenderStatePrivate(Render::AlphaCoverageStateMask)
    {}

    Q_DECLARE_PUBLIC(QAlphaCoverage)
};

/*!
    The constructor creates a new QAlphaCoverage::QAlphaCoverage instance
    with the specified \a parent.
 */
QAlphaCoverage::QAlphaCoverage(QNode *parent)
    : QRenderState(*new QAlphaCoveragePrivate, parent)
{
}

/*! \internal */
QAlphaCoverage::~QAlphaCoverage()
{
}

} // namespace Qt3DRender

QT_END_NAMESPACE