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/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the Qt Graphical Effects module.
**
** $QT_BEGIN_LICENSE:BSD$
** You may use this file under the terms of the BSD license as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
** * Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** * Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in
** the documentation and/or other materials provided with the
** distribution.
** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
** of its contributors may be used to endorse or promote products derived
** from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/
import QtQuick 2.0
import "private"
/*!
\qmltype Displace
\inqmlmodule QtGraphicalEffects
\since QtGraphicalEffects 1.0
\inherits QtQuick2::Item
\ingroup qtgraphicaleffects-distortion
\brief Moves the pixels of the source item according to the given
displacement map.
\table
\header
\li Source
\li DisplacementSource
\li Effect applied
\row
\li \image Original_bug.png
\li \image Displace_map.png
\li \image Displace_bug.png
\endtable
\section1 Example
The following example shows how to apply the effect.
\snippet Displace-example.qml example
*/
Item {
id: rootItem
/*!
This property defines the source item for the pixels that are going to
be displaced according to the data from
\l{Displace::displacementSource}{displacementSource}.
\note It is not supported to let the effect include itself, for
instance by setting source to the effect's parent.
*/
property variant source
/*!
This property defines the item that is going to be used as the
displacement map. The displacementSource item gets rendered into the
intermediate pixel buffer. The red and green component values from the
result determine the displacement of the pixels from the source item.
The format for the displacement map is similar to the tangent space
normal maps, which can be created with most 3D-modeling tools. Many
image processing tools include the support for generating normal maps.
Alternatively, the displacement map for this effect can also be a QML
element which is colored appropriately. Like any QML element, it can be
animated. It is recommended that the size of the diplacement map matches
the size of the \l{Displace::source}{source}.
The displace data is interpreted in the RGBA format. For every pixel:
the red channel stores the x-axis displacement, and the green channel
stores the y-axis displacement. Blue and alpha channels are ignored for
this effect.
Assuming that red channel value 1.0 is fully red (0.0 having no red at
all), this effect considers pixel component value 0.5 to cause no
displacement at all. Values above 0.5 shift pixels to the left, values
below 0.5 do the shift to the right. In a similar way, green channel
values above 0.5 displace the pixels upwards, and values below 0.5 shift
the pixels downwards. The actual amount of displacement in pixels
depends on the \l displacement property.
*/
property variant displacementSource
/*!
This property defines the scale for the displacement. The bigger scale,
the bigger the displacement of the pixels. The value set to 0.0 causes
no displacement.
The value ranges from -1.0 (inverted maximum shift, according to
displacementSource) to 1.0 (maximum shift, according to
displacementSource). By default, the property is set to \c 0.0 (no
displacement).
\table
\header
\li Output examples with different displacement values
\li
\li
\row
\li \image Displace_displacement1.png
\li \image Displace_displacement2.png
\li \image Displace_displacement3.png
\row
\li \b { displacement: -0.2 }
\li \b { displacement: 0.0 }
\li \b { displacement: 0.2 }
\endtable
*/
property real displacement: 0.0
/*!
This property allows the effect output pixels to be cached in order to
improve the rendering performance.
Every time the source or effect properties are changed, the pixels in
the cache must be updated. Memory consumption is increased, because an
extra buffer of memory is required for storing the effect output.
It is recommended to disable the cache when the source or the effect
properties are animated.
By default, the property is set to \c false.
*/
property bool cached: false
SourceProxy {
id: sourceProxy
input: rootItem.source
}
SourceProxy {
id: displacementSourceProxy
input: rootItem.displacementSource
}
ShaderEffectSource {
id: cacheItem
anchors.fill: parent
visible: rootItem.cached
smooth: true
sourceItem: shaderItem
live: true
hideSource: visible
}
ShaderEffect {
id: shaderItem
property variant source: sourceProxy.output
property variant displacementSource: displacementSourceProxy.output
property real displacement: rootItem.displacement
property real xPixel: 1.0/width
property real yPixel: 1.0/height
anchors.fill: parent
fragmentShader: "
varying highp vec2 qt_TexCoord0;
uniform highp float qt_Opacity;
uniform lowp sampler2D source;
uniform lowp sampler2D displacementSource;
uniform highp float displacement;
uniform highp float xPixel;
uniform highp float yPixel;
highp float linearstep(highp float e0, highp float e1, highp float x) {
return clamp((x - e0) / (e1 - e0), 0.0, 1.0);
}
void main() {
lowp vec4 offset = texture2D(displacementSource, qt_TexCoord0);
offset.xy -= vec2(0.5, 0.5);
offset.xy = offset.xy * step(vec2(1.0/256.0), abs(offset.xy));
highp vec2 tx = qt_TexCoord0 + (vec2(-offset.x, offset.y) * displacement);
lowp float e1 = linearstep(0.0, xPixel, tx.x);
lowp float e2 = linearstep(0.0, yPixel, tx.y);
lowp float e3 = 1.0 - linearstep(1.0, 1.0 + xPixel, tx.x);
lowp float e4 = 1.0 - linearstep(1.0, 1.0 + yPixel, tx.y);
lowp vec4 sample = texture2D(source, tx);
sample.rgb *= e1 * e2 * e3 * e4;
gl_FragColor = sample * qt_Opacity * offset.a;
}
"
}
}
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