LevelOfDetail provides a way of controlling the complexity of rendered entities based on their size on the screen. 更多...
导入语句: | import Qt3D.Render 2.2 |
Since: | Qt 5.9 |
实例化: | QLevelOfDetail |
继承: | Component3D |
LevelOfDetail 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.
currentIndex property can then be used, for example, to enable or disable entities, change source in an EntityLoader , or material.
The LevelOfDetail component is not shareable between multiple Entity's.
import Qt3D.Core 2.0 import Qt3D.Render 2.0 Entity { id: root // Scene Camera { id: mainCamera } LevelOfDetail { id: lod camera: mainCamera thresholds: [20, 35, 50, 65] thresholdType: LevelOfDetail.DistanceToCameraThreshold } GeometryRenderer { id: mesh view: CylinderMesh { property var sliceValues: [20, 10, 6, 4] slices: sliceValues[lod.currentIndex] } } Entity { id: renderableEntity components: [ mesh, lod ] } }
ThresholdType : enumeration |
Specifies how the values in the thresholds are interpreted
另请参阅 Qt3DRender::QLevelOfDetail::ThresholdType .
camera : Camera |
Holds the id of the camera that is used to compute the actual distance or the screen size.
currentIndex : int |
The index in the range array which matches the current distance to the camera or screen size.
thresholdType : int |
Specifies how range values are interpreted.
thresholds : QList < qreal > |
Array of range values as float point numbers. The value for the most detailed representation should be specified first.
若 LevelOfDetail::thresholdType 被设为 LevelOfDetail .DistanceToCameraThreshold, values should be specified in ascending order, in camera space coordinates
若 LevelOfDetail::thresholdType 被设为 LevelOfDetail .ProjectedScreenPixelSizeThreshold, values should be specified in descending order, in screen space pixels.
volumeOverride : int |
Specifies what is used to evaluate the distance or screen size.
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 null, the bounding volume of the entity is used. Care must be taken that this bounding volume never becomes invalid.