191 lines
6.9 KiB
QML
191 lines
6.9 KiB
QML
/****************************************************************************
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**
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** Copyright (C) 2017 The Qt Company Ltd.
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** Contact: https://www.qt.io/licensing/
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**
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** This file is part of the Qt Graphical Effects module.
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**
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** $QT_BEGIN_LICENSE:LGPL$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and The Qt Company. For licensing terms
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** and conditions see https://www.qt.io/terms-conditions. For further
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** information use the contact form at https://www.qt.io/contact-us.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 3 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL3 included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU Lesser General Public License version 3 requirements
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** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
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**
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** GNU General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU
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** General Public License version 2.0 or (at your option) the GNU General
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** Public license version 3 or any later version approved by the KDE Free
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** Qt Foundation. The licenses are as published by the Free Software
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** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
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** included in the packaging of this file. Please review the following
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** information to ensure the GNU General Public License requirements will
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** be met: https://www.gnu.org/licenses/gpl-2.0.html and
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** https://www.gnu.org/licenses/gpl-3.0.html.
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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import QtQuick 2.12
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import QtGraphicalEffects.private 1.12
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/*!
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\qmltype Displace
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\inqmlmodule QtGraphicalEffects
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\since QtGraphicalEffects 1.0
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\inherits QtQuick2::Item
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\ingroup qtgraphicaleffects-distortion
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\brief Moves the pixels of the source item according to the given
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displacement map.
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\table
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\header
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\li Source
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\li DisplacementSource
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\li Effect applied
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\row
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\li \image Original_bug.png
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\li \image Displace_map.png
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\li \image Displace_bug.png
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\endtable
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\note This effect is available when running with OpenGL.
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\section1 Example
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The following example shows how to apply the effect.
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\snippet Displace-example.qml example
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*/
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Item {
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id: rootItem
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/*!
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This property defines the source item for the pixels that are going to
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be displaced according to the data from
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\l{Displace::displacementSource}{displacementSource}.
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\note It is not supported to let the effect include itself, for
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instance by setting source to the effect's parent.
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*/
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property variant source
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/*!
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This property defines the item that is going to be used as the
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displacement map. The displacementSource item gets rendered into the
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intermediate pixel buffer. The red and green component values from the
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result determine the displacement of the pixels from the source item.
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The format for the displacement map is similar to the tangent space
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normal maps, which can be created with most 3D-modeling tools. Many
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image processing tools include the support for generating normal maps.
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Alternatively, the displacement map for this effect can also be a QML
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element which is colored appropriately. Like any QML element, it can be
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animated. It is recommended that the size of the diplacement map matches
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the size of the \l{Displace::source}{source}.
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The displace data is interpreted in the RGBA format. For every pixel:
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the red channel stores the x-axis displacement, and the green channel
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stores the y-axis displacement. Blue and alpha channels are ignored for
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this effect.
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Assuming that red channel value 1.0 is fully red (0.0 having no red at
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all), this effect considers pixel component value 0.5 to cause no
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displacement at all. Values above 0.5 shift pixels to the left, values
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below 0.5 do the shift to the right. In a similar way, green channel
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values above 0.5 displace the pixels upwards, and values below 0.5 shift
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the pixels downwards. The actual amount of displacement in pixels
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depends on the \l displacement property.
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*/
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property variant displacementSource
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/*!
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This property defines the scale for the displacement. The bigger scale,
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the bigger the displacement of the pixels. The value set to 0.0 causes
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no displacement.
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The value ranges from -1.0 (inverted maximum shift, according to
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displacementSource) to 1.0 (maximum shift, according to
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displacementSource). By default, the property is set to \c 0.0 (no
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displacement).
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\table
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\header
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\li Output examples with different displacement values
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\li
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\li
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\row
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\li \image Displace_displacement1.png
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\li \image Displace_displacement2.png
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\li \image Displace_displacement3.png
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\row
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\li \b { displacement: -0.2 }
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\li \b { displacement: 0.0 }
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\li \b { displacement: 0.2 }
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\endtable
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*/
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property real displacement: 0.0
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/*!
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This property allows the effect output pixels to be cached in order to
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improve the rendering performance.
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Every time the source or effect properties are changed, the pixels in
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the cache must be updated. Memory consumption is increased, because an
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extra buffer of memory is required for storing the effect output.
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It is recommended to disable the cache when the source or the effect
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properties are animated.
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By default, the property is set to \c false.
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*/
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property bool cached: false
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SourceProxy {
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id: sourceProxy
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input: rootItem.source
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}
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SourceProxy {
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id: displacementSourceProxy
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input: rootItem.displacementSource
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}
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ShaderEffectSource {
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id: cacheItem
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anchors.fill: parent
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visible: rootItem.cached
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smooth: true
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sourceItem: shaderItem
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live: true
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hideSource: visible
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}
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ShaderEffect {
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id: shaderItem
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property variant source: sourceProxy.output
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property variant displacementSource: displacementSourceProxy.output
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property real displacement: rootItem.displacement
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property real xPixel: 1.0/width
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property real yPixel: 1.0/height
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anchors.fill: parent
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fragmentShader: "qrc:/qt-project.org/imports/QtGraphicalEffects/shaders/displace.frag"
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}
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}
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