QLevelOfDetail Class▲
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Header: QLevelOfDetail
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Since: Qt 5.9
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CMake:
find_package(Qt6 REQUIRED COMPONENTS 3drender)
target_link_libraries(mytarget PRIVATE Qt6::3drender)
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qmake: QT += 3drender
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Inherited By: Qt3DRender::QLevelOfDetailSwitch
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Instantiated By: qml-qt3d-render-levelofdetail.xml
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Inherits: Qt3DCore::QComponent
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Inherited By: Qt3DRender::QLevelOfDetailSwitch
Detailed Description▲
QLevelOfDetail can be used to control the representation of an entity based on distance from the observer or size on the screen.
In order to improve rendering performance, objects that are very small can be rendered using far fewer details, in geometry or texture.
The component is controlled by specifying thresholds of values which are interpreted as either distances from the camera or screen size.
As the point of view changes, the currentIndex property will change to reflect matching value in the range array.
The currentIndex property can then be used, for example, to enable or disable entities, change material, etc.
The LevelOfDetail component is not shareable between multiple entities.
#include <Qt3DCore/QEntity>
#include <Qt3DRender/QGeometryRenderer>
#include <Qt3DRender/QLevelOfDetail>
// Scene
Qt3DCore::QEntity *rootEntity = new Qt3DCore::Qt3DCore::QEntity;
Qt3DCore::QEntity *renderableEntity = new Qt3DCore::QEntity(rootEntity);
Qt3DRender::QGeometryRenderer *geometryRenderer = new Qt3DCore::QGeometryRenderer(renderableEntity);
renderableEntity->addComponent(geometryRenderer);
Qt3DRender::QLevelOfDetail* lod = new Qt3Render::QLevelOfDetail(renderableEntity);
QList<qreal> thresholds = {20, 35, 50, 65};
lod->setThresholds(thresholds);
lod->setCamera(mainCamera);
renderableEntity->addComponent(lod);
// connect to QLevelOfDetail::currentIndexChanged to toggle rendering
...Member Type Documentation▲
enum QLevelOfDetail::ThresholdType▲
Specifies how the values in the thresholds are interpreted
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Constant |
Value |
Description |
|---|---|---|
|
Qt3DRender::QLevelOfDetail::DistanceToCameraThreshold |
0 |
Distance from the entity to the selected camera |
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Qt3DRender::QLevelOfDetail::ProjectedScreenPixelSizeThreshold |
1 |
Size of the entity when projected on the screen as seen from the selected camera, expressed in number of pixels on the side of the bounding square in screen space. |
Property Documentation▲
camera : Qt3DRender::QCamera*▲
Holds the id of the camera that is used to compute the actual distance or the screen size.
Access functions:
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*camera() const
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void setCamera( *camera)
Notifier signal:
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void cameraChanged( *camera)
currentIndex : int▲
The index in the range array which matches the current distance to the camera or screen size.
Access functions:
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int currentIndex() const
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void setCurrentIndex(int currentIndex)
Notifier signal:
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void currentIndexChanged(int currentIndex)
thresholdType : ThresholdType▲
Specifies how range values are interpreted.
Access functions:
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thresholdType() const
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void setThresholdType( thresholdType)
Notifier signal:
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void thresholdTypeChanged( thresholdType)
See Also▲
thresholds : QList<qreal>▲
Array of range values as float point numbers. The value for the most detailed representation should be specified first.
If Qt3DRender::QLevelOfDetail::thresholdType is set to Qt3DRender::QLevelOfDetail::DistanceToCameraThreshold, values should be specified in ascending order, in camera space coordinates
If Qt3DRender::QLevelOfDetail::thresholdType is set to Qt3DRender::QLevelOfDetail::ProjectedScreenPixelSizeThreshold, values should be specified in descending order, in screen space pixels.
Access functions:
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<qreal> thresholds() const
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void setThresholds(const <qreal> &thresholds)
Notifier signal:
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void thresholdsChanged(const <qreal> &thresholds)
See Also▲
volumeOverride : Qt3DRender::QLevelOfDetailBoundingSphere▲
The default is a sphere of radius 1 and centered at the local origin of the entity. This proxy volume is used to compute the distance to the camera or the size of the screen projection.
If this value to nullptr, the bounding volume of the entity is used. Care must be taken that this bounding volume never becomes invalid.
Access functions:
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volumeOverride() const
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void setVolumeOverride(const &volumeOverride)
Notifier signal:
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void volumeOverrideChanged(const &volumeOverride)
See Also▲
Member Function Documentation▲
[explicit] QLevelOfDetail::QLevelOfDetail(Qt3DCore::QNode *parent = nullptr)▲
Constructs a new QLevelOfDetail with the specified parent.
void QLevelOfDetail::setCamera(Qt3DRender::QCamera *camera)▲
Sets the camera relative to which distance and size are computed.
Setter function for property camera.
See Also▲
See also camera()
void QLevelOfDetail::setCurrentIndex(int currentIndex)▲
Sets the currentIndex.
This should not normally be set by the user.
However, if the component is disabled, then changing the current index is a simple way of switching between multiple representations.
Setter function for property currentIndex.
See Also▲
See also currentIndex()
void QLevelOfDetail::setThresholdType(Qt3DRender::QLevelOfDetail::ThresholdType thresholdType)▲
Sets the way thresholds values are interpreted with parameter thresholdType
Setter function for property thresholdType.
See Also▲
void QLevelOfDetail::setThresholds(const QList<qreal> &thresholds)▲
Sets the range values in thresholds.
Setter function for property thresholds.
See Also▲
See also thresholds(), Qt3DRender::QLevelOfDetail::thresholdType