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Qt3D Core: Difference between revisions

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[[Category:Developing_with_Qt::Qt3D]]<br />[toc align_right=&quot;yes&amp;quot; depth=&quot;3&amp;quot;]


= Qt3D Core =
 
[[Category:Developing_with_Qt::Qt3D]]
 
 


== Core elements ==
== Core elements ==
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==== Transformations ====
==== Transformations ====


===== * '''Transform'''<br />A Component that contains a list of transformation<br /><code>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 /> }</code> =====
::* '''Transform'''
::A Component that contains a list of transformation
<code>Transform {
id : transform_0
Rotate {
axis : Qt.vector3d(0,1,0)
angle : 30
}
Scale {
scale3D : Qt.vector3d(0.5, 0.25, 0.5)
}
Translate {
dx : –9; dy : 2; dz : 20
}
}</code>  


===== * '''LookAtTransform'''<br />Performs a LookAtTransform. =====
::* '''LookAtTransform'''
::Performs a LookAtTransform.  
::* '''MatrixTransform'''
::Performs a transformation based on the Matrix provided.


===== * '''MatrixTransform'''<br />Performs a transformation based on the Matrix provided. =====
::* '''TranslateTransform'''
::Performs a translation.  


===== * '''TranslateTransform'''<br />Performs a translation. =====
::* '''RotateTransform'''
::Performs a rotation around an axis.  


===== * '''RotateTransform'''<br />Performs a rotation around an axis. =====
::* '''ScaleTransform'''
::Performs a scaling.  


===== * '''ScaleTransform'''<br />Performs a scaling. =====
http://i58.tinypic.com/2poe3bn.png
 
[[Image:http://i58.tinypic.com/2poe3bn.png|http://i58.tinypic.com/2poe3bn.png]]


==== Others Components ====
==== Others Components ====


===== * '''CameraLens'''<br />Contains the lens properties of a Camera.<br />'''''' Projection Type<br />'''''' Far plane<br />'''''' Near plane<br />'''''' Field of view<br />'''''' Aspect ratio =====
::* '''CameraLens'''
::Contains the lens properties of a Camera.
'''''' Projection Type
'''''' Far plane
'''''' Near plane
'''''' Field of view
'''''' Aspect ratio =====


=== Custom elements ===
=== Custom elements ===


Custom elements can be created by subclassing an Entity and predefining a set of properties.
::Custom elements can be created by subclassing an Entity and predefining a set of properties.
 
::* '''Camera'''
===== * '''Camera'''<br />The Camera elements is an Entity that contains a Transform and a CameraLens.<br /><code>Camera {<br /> id : camera2 =====
::The Camera elements is an Entity that contains a Transform and a CameraLens.
<code>Camera {
id : camera2 =====


lens : CameraLens {<br /> projectionType: CameraLens.PerspectiveProjection<br /> fieldOfView: 45<br /> aspectRatio: 16/9<br /> nearPlane : 0.01<br /> farPlane : 1000.0<br /> }
lens : CameraLens {
projectionType: CameraLens.PerspectiveProjection
fieldOfView: 45
aspectRatio: 16/9
nearPlane : 0.01
farPlane : 1000.0
}


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 /> }</code>
transform : Transform {
LookAt {
position: Qt.vector3d( 0.0, –1.0, –5.0 )
upVector: Qt.vector3d( 0.0, 1.0, 0.0 )
viewCenter: Qt.vector3d( 0.0, 2.0, 10.0 )
}
Rotate {
axis : Qt.vector3d(0, 0, 1)
angle : 40
}
}
}</code>


== Resources Management ==
== Resources Management ==
Line 57: Line 102:
* QListResourcesManager
* 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.<br />This should lower the amount of cache misses and speed up rendering.
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 :<br />* QCircularBuffer
Other Resources management oriented classes include :
* QCircularBuffer

Latest revision as of 08:19, 30 March 2015



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 {
 id : transform_0
 Rotate {
 axis : Qt.vector3d(0,1,0)
 angle : 30
 }
 Scale {
 scale3D : Qt.vector3d(0.5, 0.25, 0.5)
 }
 Translate {
 dx : –9; dy : 2; dz : 20
 }
 }
  • 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.

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 {
 id : camera2 =====

lens : CameraLens {
 projectionType: CameraLens.PerspectiveProjection
 fieldOfView: 45
 aspectRatio: 16/9
 nearPlane : 0.01
 farPlane : 1000.0
 }

transform : Transform {
 LookAt {
 position: Qt.vector3d( 0.0, –1.0, –5.0 )
 upVector: Qt.vector3d( 0.0, 1.0, 0.0 )
 viewCenter: Qt.vector3d( 0.0, 2.0, 10.0 )
 }
 Rotate {
 axis : Qt.vector3d(0, 0, 1)
 angle : 40
 }
 }
 }

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
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