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Qt3D Core
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Qt3D Core
Core elements
The Core exposes a few default elements that make up all Qt3D scenes.
Node
A base Qt3D element.
Entity
An Entity is a Node which has a list of Component properties. This is the type of elements that are actually rendered.
Component
Components are elements that are used to further specify an Entity.
Transformations
* Transform
A Component that contains a list of transformation
Transform {<br /> id : transform_0<br /> Rotate {<br /> axis : Qt.vector3d(0,1,0)<br /> angle : 30<br /> }<br /> Scale {<br /> scale3D : Qt.vector3d(0.5, 0.25, 0.5)<br /> }<br /> Translate {<br /> dx : –9; dy : 2; dz : 20<br /> }<br /> }
Transform {<br /> id : transform_0<br /> Rotate {<br /> axis : Qt.vector3d(0,1,0)<br /> angle : 30<br /> }<br /> Scale {<br /> scale3D : Qt.vector3d(0.5, 0.25, 0.5)<br /> }<br /> Translate {<br /> dx : –9; dy : 2; dz : 20<br /> }<br /> }
* LookAtTransform
Performs a LookAtTransform.
* MatrixTransform
Performs a transformation based on the Matrix provided.
* TranslateTransform
Performs a translation.
* RotateTransform
Performs a rotation around an axis.
* ScaleTransform
Performs a scaling.
http://i58.tinypic.com/2poe3bn.png
Others Components
* CameraLens'
Contains the lens properties of a Camera.
' Projection Type
' Far plane
' Near plane
' Field of view
' Aspect ratio
Custom elements
Custom elements can be created by subclassing an Entity and predefining a set of properties.
===== * Camera
The Camera elements is an Entity that contains a Transform and a CameraLens.
Camera {<br /> id : camera2 =====
lens : CameraLens {<br /> projectionType: CameraLens.PerspectiveProjection<br /> fieldOfView: 45<br /> aspectRatio: 16/9<br /> nearPlane : 0.01<br /> farPlane : 1000.0<br /> }
transform : Transform {<br /> LookAt {<br /> position: Qt.vector3d( 0.0, –1.0, –5.0 )<br /> upVector: Qt.vector3d( 0.0, 1.0, 0.0 )<br /> viewCenter: Qt.vector3d( 0.0, 2.0, 10.0 )<br /> }<br /> Rotate {<br /> axis : Qt.vector3d(0, 0, 1)<br /> angle : 40<br /> }<br /> }<br /> }
Resources Management
To achieve high rendering performances, the memory access to the resources has to be properly managed and structured. Therefore, a set of templated resources management oriented classes have been developed in the core of Qt3D.
- QHandle
- QArrayResourcesManager
- QListResourcesManager
The use of a Handle systems allows for resources to be easily accessed and managed while allowing for memory structure to be realigned so as to maintain a contiguous memory alignment and reduce fragmentation.
This should lower the amount of cache misses and speed up rendering.
Other Resources management oriented classes include :
* QCircularBuffer