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| |
| import QtQuick 2.12 |
| import QtGraphicalEffects.private 1.12 |
| |
| /*! |
| \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 |
| |
| \note This effect is available when running with OpenGL. |
| |
| \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: "qrc:/qt-project.org/imports/QtGraphicalEffects/shaders/displace.frag" |
| } |
| } |