Qt 5.6 | Qt Canvas 3D | Qt Quick Item as Texture Example

Qt 5.6.2 Reference Documentation

# Qt Quick Item as Texture Example

The Qt Quick Item as Texture example shows how to use other Qt Quick items as a texture source for Qt Canvas3D textures.

## Using Qt Quick Item as a Texture

First we create a Rectangle with a label that displays the current frame rate and rotation values of the cube:

      Rectangle {
          id: textureSource
          color: "lightgreen"
          width: 256
          height: 256
          border.color: "blue"
          border.width: 4
          layer.enabled: true
          layer.smooth: true
          Label {
              anchors.fill: parent
              anchors.margins: 16
              text: "X Rot:" + (canvas3d.xRotAnim | 0) + "\n"
                  + "Y Rot:" + (canvas3d.yRotAnim | 0) + "\n"
                  + "Z Rot:" + (canvas3d.zRotAnim | 0) + "\n"
                  + "FPS:" + canvas3d.fps
              color: "red"
              font.pointSize: 26
              horizontalAlignment: Text.AlignLeft
              verticalAlignment: Text.AlignVCenter
          }
      }

We want to use the above Rectangle as the texture on our 3D cube. As a Rectangle item doesn't implement QQuickItem::textureProvider() by itself, we make it layered by setting the `layer.enabled` property to `true`.

To create a Canvas3DTexture out of our layered Rectangle, we create a QTCANVAS3D_texture_provider extension and the texture in the `initializeGL()` function in our JavaScript implementation:

      canvasTextureProvider = gl.getExtension("QTCANVAS3D_texture_provider");
      cubeTexture = canvasTextureProvider.createTextureFromSource(textureSourceItem);

Once the `cubeTexture` item is created, it can be used like any other texture item in the JavaScript.

Note: The method of creating the texture from a Qt Quick item differs from how one would create texture from an HTML item in WebGL API. Textures created with QTCANVAS3D_texture_provider extension support automatic live updates, without having to call textureImage2D each frame to re-upload fresh texture data from the item.

Files:

- quickitemtexture/qml/quickitemtexture/main.qml
- quickitemtexture/qml/quickitemtexture/quickitemtexture.js
- quickitemtexture/main.cpp
- quickitemtexture/quickitemtexture.pro
- quickitemtexture/quickitemtexture.qrc