QQuick3DTextureData Class

Detailed Description

The QQuick3DTextureData class can be used to specify custom texture data for a Texture in a Qt Quick 3D scene.

While not strictly required, the typical usage is to inherit from this class. The subclass is then exposed to QML by registering it to the type system. The textureData property of a Texture can then be set to reference an instance of the registered type.

Example implementation:

 class CustomTextureData : public QQuick3DTextureData
 {
     Q_OBJECT
     ... properties ...

 public:
     CustomTextureData() { regenerateTextureData(); }

     void setProperty(...)
     {
         // Change relevant internal data.
         // ...

         // Update the texture data
         regenerateTextureData();

         // Finally, trigger an update. This is relevant in case nothing else
         // is changed in the scene; this way we make sure a new frame will
         // be rendered
         update();
     }
 private:
     void regenerateTextureData()
     {
         QByteArray textureData;
         textureData = generateTextureData();
         setTextureData(textureData);
         setSize(QSize(256, 256));
         setFormat(QQuick3DTextureData::Format::RGBA8)
         setHasTransparency(true);
     }
 };

This class can then be registered as a QML type and used with Texture.

In Qt 5 type registration happened with qmlRegisterType:

 qmlRegisterType<MyCustomTextureData>("Example", 1, 0, "MyCustomTextureData");

In Qt 6 the default approach is to use automatic registration with the help of the build system. Instead of calling qmlRegisterType, the .pro file can now contain:

 CONFIG += qmltypes
 QML_IMPORT_NAME = Example
 QML_IMPORT_MAJOR_VERSION = 1

With CMake, automatic registration is the default behavior, so no special settings are needed beyond basic QML module setup:

 qt_add_qml_module(application
     URI Example
     VERSION 1.0
 )

The class implementation should add QML_NAMED_ELEMENT:

 class CustomTextureData : public QQuick3DTextureData
 {
     Q_OBJECT
     QML_NAMED_ELEMENT(MyCustomTextureData)
     ...
 };

The QML code can then use the custom type:

 import Example 1.0

 Model {
     source: "#Cube"
     materials: [
         DefaultMaterial {
             diffuseMap: diffuseMapCustomTexture
         }
     ]
     Texture {
         id: diffuseMapCustomTexture
         textureData: MyCustomTextureData { }
     }
 }