Qt 5.6 | Qt Canvas 3D | Interactive Mobile Phone Example

Qt 5.6.2 Reference Documentation

# Interactive Mobile Phone Example

This example demonstrates how to implement an application that uses Qt Quick 2D element as a texture in a three.js scene. The example shows a 3D model of a mobile phone with an UI implemented with Qt Quick. When the phone is not rotating, the UI can be interacted with.

## Qt Quick Implementation

The Qt Quick Implementation main.qml of the example renders the 3D model of the mobile phone using Canvas3D type. The phone UI is composed of the `textureSource` Qt Quick item and its children. To make it possible to use the item as a texture source for Canvas3D, we must enable the layer of the item:

      Item {
          id: textureSource
          layer.enabled: true
          layer.smooth: true
          layer.textureMirroring: ShaderEffectSource.NoMirroring
          ...

The texture mirroring is disabled so that the OpenGL texture generated from the item is oriented as the three.js expects.

The `textureSource` item is passed as a parameter to the JavaScript function handling the OpenGL initialization in Canvas3D:

      onInitializeGL: GLCode.initializeGL(canvas3d, textureSource)

The texture generated from the `textureSource` is not interactable by itself, as it is just a regular texture. To make it appear interactable, we make it so that the phone UI is interactable only when the phone is not rotating and superimpose the actual `textureSource` item over the Canvas3D so that both the 3D model and the `textureSource` items are perfectly aligned. The 3D model and the Qt Quick UI are aligned by careful positioning of the model and scaling of the `textureSource` item using its transform property. The `textureSource` item is set fully transparent so that there are no visual artifacts:

      transform: [
          Scale {
              origin.y: textureSource.height / 2
              origin.x: textureSource.width / 2
              yScale: 0.5 * mainView.height / mainView.initialHeight
              xScale: 0.5 * mainView.height / mainView.initialHeight
          }
      ]
      opacity: 0.0

To ensure user cannot interact with the UI when the phone is rotating, we hide the `textureSource` item behind the Canvas3D by adjusting its z property when the phone starts its rotation animation.

## The JavaScript Code

The JavaScript side of the implementation, cellphone.js, is done using a version of `three.js` that is ported for Qt Canvas 3D: three.js.

The `initializeGL()` method creates the scene. It also adds the lights and the camera to the scene and creates materials and meshes used in the scene. The part relevant to the main point of this example is how the `textureSource` is handled. It is very simple to create a texture from a Qt Quick texture source: simply create a new `THREE.QtQuickItemTexture` with the `textureSource` as a parameter and you are done:

      var frontTexture = new THREE.QtQuickItemTexture( textureSource );

The texture created this way can be used as a map to a material just like a regular texture:

      var frontMaterial = new THREE.MeshPhongMaterial( { map: frontTexture } );

The scene is rendered in `paintGL()` method, which simply adjusts the rotations of the phone meshes, repositions the camera and light, and renders the scene.

For more information on how to use `three.js` the documentation is available here: three.js/docs

The background sphere uses Pluto texture map, which is Copyright (c) by James Hastings-Trew http://planetpixelemporium.com/planets.html. Used with permission.

Files:

- threejs/cellphone/qml/cellphone/cellphone.js
- threejs/cellphone/qml/cellphone/cellphoneapp.qml
- threejs/cellphone/qml/cellphone/cellphonecanvas.qml
- threejs/cellphone/qml/cellphone/colorselector.qml
- threejs/cellphone/qml/cellphone/fpsdisplay.qml
- threejs/cellphone/qml/cellphone/main.qml
- threejs/cellphone/main.cpp
- threejs/cellphone/cellphone.pro
- threejs/cellphone/cellphone.qrc

Images:

- threejs/cellphone/images/calendar.png
- threejs/cellphone/images/camera.png
- threejs/cellphone/images/clock.png
- threejs/cellphone/images/contacts.png
- threejs/cellphone/images/gallery.png
- threejs/cellphone/images/games.png
- threejs/cellphone/images/lock.png
- threejs/cellphone/images/mail.png
- threejs/cellphone/images/maps.png
- threejs/cellphone/images/menu_background.jpg
- threejs/cellphone/images/music.png
- threejs/cellphone/images/plutomap1k.jpg
- threejs/cellphone/images/qtlogo_with_alpha.png
- threejs/cellphone/images/settings.png
- threejs/cellphone/images/todo.png
- threejs/cellphone/images/videos.png