QLevelOfDetail Class
class Qt3DRender::QLevelOfDetailThe QLevelOfDetail class provides a way of controlling the complexity of rendered entities based on their size on the screen. More...
Header: | #include <QLevelOfDetail> |
qmake: | QT += 3drender |
Since: | Qt 5.9 |
Instantiated By: | LevelOfDetail |
Inherits: | Qt3DCore::QComponent |
Inherited By: |
This class was introduced in Qt 5.9.
Public Types
enum | ThresholdType { DistanceToCameraThreshold, ProjectedScreenPixelSizeThreshold } |
Public Functions
void | setCamera(Qt3DRender::QCamera *camera) |
void | setCurrentIndex(int currentIndex) |
void | setThresholdType(Qt3DRender::QLevelOfDetail::ThresholdType thresholdType) |
void | setThresholds(const QVector<qreal> &thresholds) |
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); QVector<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
Constant | Value | Description |
---|---|---|
Qt3DRender::QLevelOfDetail::DistanceToCameraThreshold | 0 | Distance from the entity to the selected camera |
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. |
Member Function Documentation
void QLevelOfDetail::setCamera(Qt3DRender::QCamera *camera)
Sets the camera relative to which distance and size are computed.
void QLevelOfDetail::setCurrentIndex(int currentIndex)
Sets the currentIndex.
Note: 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.
void QLevelOfDetail::setThresholdType(Qt3DRender::QLevelOfDetail::ThresholdType thresholdType)
Sets the way thresholds values are interpreted with parameter thresholdType
See also Qt3DRender::QLevelOfDetail::ThresholdType.
void QLevelOfDetail::setThresholds(const QVector<qreal> &thresholds)
Sets the range values in thresholds.
See also Qt3DRender::QLevelOfDetail::thresholdType.