QSGNode Class
The QSGNode class is the base class for all nodes in the scene graph. More...
| Header: | #include <QSGNode> |
| qmake: | QT += quick |
| Inherited By: | QSGBasicGeometryNode, QSGOpacityNode, QSGRenderNode, and QSGTransformNode |
Public Types
| enum | DirtyStateBit { DirtyMatrix, DirtyNodeAdded, DirtyNodeRemoved, DirtyGeometry, DirtyMaterial, …, DirtySubtreeBlocked } |
| enum | Flag { OwnedByParent, UsePreprocess, OwnsGeometry, OwnsMaterial, OwnsOpaqueMaterial, InternalReserved } |
| enum | NodeType { BasicNodeType, GeometryNodeType, TransformNodeType, ClipNodeType, OpacityNodeType, RenderNodeType } |
Detailed Description
The QSGNode class can be used as a child container. Children are added with the appendChildNode(), prependChildNode(), insertChildNodeBefore() and insertChildNodeAfter(). The order of nodes is important as geometry nodes are rendered according to their ordering in the scene graph.
The scene graph nodes contains a mechanism to describe which parts of the scene has changed. This includes the combined matrices, accumulated opacity, changes to the node hierarchy, and so on. This information can be used for optimizations inside the scene graph renderer. For the renderer to properly render the nodes, it is important that users call QSGNode::markDirty() with the correct flags when nodes are changed. Most of the functions on the node classes will implicitly call markDirty(). For example, QSGNode::appendChildNode() will call markDirty() passing in QSGNode::DirtyNodeAdded.
If nodes change every frame, the preprocess() function can be used to apply changes to a node for every frame it is rendered. The use of preprocess() must be explicitly enabled by setting the QSGNode::UsePreprocess flag on the node.
The virtual isSubtreeBlocked() function can be used to disable a subtree all together. Nodes in a blocked subtree will not be preprocessed() and not rendered.
Note: All classes with QSG prefix should be used solely on the scene graph's rendering thread. See Scene Graph and Rendering for more information.
Member Type Documentation
enum QSGNode::DirtyStateBit
Used in QSGNode::markDirty() to indicate how the scene graph has changed.
| Constant | Value | Description |
|---|---|---|
QSGNode::DirtyMatrix | 0x0100 | The matrix in a QSGTransformNode has changed. |
QSGNode::DirtyNodeAdded | 0x0400 | A node was added. |
QSGNode::DirtyNodeRemoved | 0x0800 | A node was removed. |
QSGNode::DirtyGeometry | 0x1000 | The geometry of a QSGGeometryNode has changed. |
QSGNode::DirtyMaterial | 0x2000 | The material of a QSGGeometryNode has changed. |
QSGNode::DirtyOpacity | 0x4000 | The opacity of a QSGOpacityNode has changed. |
QSGNode::DirtySubtreeBlocked | 0x0080 | The subtree has been blocked. |
See also QSGNode::markDirty().
enum QSGNode::Flag
The QSGNode::Flag enum describes flags on the QSGNode
| Constant | Value | Description |
|---|---|---|
QSGNode::OwnedByParent | 0x0001 | The node is owned by its parent and will be deleted when the parent is deleted. |
QSGNode::UsePreprocess | 0x0002 | The node's virtual preprocess() function will be called before rendering starts. |
QSGNode::OwnsGeometry | 0x00010000 | Only valid for QSGGeometryNode and QSGClipNode. The node has ownership over the QSGGeometry instance and will delete it when the node is destroyed or a geometry is assigned. |
QSGNode::OwnsMaterial | 0x00020000 | Only valid for QSGGeometryNode. The node has ownership over the material and will delete it when the node is destroyed or a material is assigned. |
QSGNode::OwnsOpaqueMaterial | 0x00040000 | Only valid for QSGGeometryNode. The node has ownership over the opaque material and will delete it when the node is destroyed or a material is assigned. |
QSGNode::InternalReserved | 0x01000000 | Reserved for internal use. |
enum QSGNode::NodeType
Can be used to figure out the type of node.
| Constant | Value | Description |
|---|---|---|
QSGNode::BasicNodeType | 0 | The type of QSGNode |
QSGNode::GeometryNodeType | 1 | The type of QSGGeometryNode |
QSGNode::TransformNodeType | 2 | The type of QSGTransformNode |
QSGNode::ClipNodeType | 3 | The type of QSGClipNode |
QSGNode::OpacityNodeType | 4 | The type of QSGOpacityNode |
QSGNode::RenderNodeType | 6 | The type of QSGRenderNode |
See also type().