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/*!
    \example canvas3d/threejs/cellphone
    \since QtCanvas3D 1.1
    \title Interactive Mobile Phone Example
    \ingroup qtcanvas3d-examples
    \brief Demonstrates using Qt Quick item as a texture with three.js.

    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.

    \image cellphone-example.png

    \section1 Qt Quick Implementation

    The Qt Quick Implementation \l{canvas3d/threejs/cellphone/qml/cellphone/main.qml}{main.qml}
    of the example renders the 3D model of the mobile phone using Canvas3D type.
    The phone UI is composed of the \c 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:

    \snippet canvas3d/threejs/cellphone/qml/cellphone/main.qml 0
    \dots

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

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

    \snippet canvas3d/threejs/cellphone/qml/cellphone/cellphonecanvas.qml 1

    The texture generated from the \c 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 \c textureSource item over the
    Canvas3D so that both the 3D model and the \c 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 \c textureSource item using its \l{Item::transform}{transform} property.
    The \c textureSource item is set fully transparent so that there are no visual artifacts:

    \snippet canvas3d/threejs/cellphone/qml/cellphone/main.qml 2

    To ensure user cannot interact with the UI when the phone is rotating, we hide the
    \c textureSource item behind the Canvas3D by adjusting its \l{Item::z}{z} property when the
    phone starts its rotation animation.

    \section1 The JavaScript Code

    The JavaScript side of the implementation,
    \l{canvas3d/threejs/cellphone/qml/cellphone/cellphone.js}{cellphone.js},
    is done using a version of \c{three.js} that is ported for \l{Qt Canvas 3D}:
    \l{https://github.com/tronlec/three.js}{three.js}.

    The \c{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 \c textureSource is handled. It is very simple to create a texture
    from a Qt Quick texture source: simply create a new \c{THREE.QtQuickItemTexture} with the
    \c textureSource as a parameter and you are done:

    \snippet canvas3d/threejs/cellphone/qml/cellphone/cellphone.js 0

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

    \snippet canvas3d/threejs/cellphone/qml/cellphone/cellphone.js 1

    The scene is rendered in \c{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 \c {three.js} the documentation is available here:
    \l{http://threejs.org/docs/}{three.js/docs}

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