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/*!
    \example jsonmodels
    \since QtCanvas3D 1.0
    \title JSON Models Example
    \ingroup qtcanvas3d-examples
    \brief Load and display several JSON models.

    The JSON Models Example demonstrates loading and displaying more than
    one JSON model and more than one texture. It also implements simple
    mouse input handling to allow rotating the scene and zooming into it.

    \image jsonmodels-example.png

    \section1 JSON Model Loader

    First we include a JSON model parser, which handles parsing the JSON
    models into our internal models:

    \snippet jsonmodels/qml/jsonmodels/jsonmodels.js 0

    The \c{ThreeJSLoader.js} includes a reimplementation of the JSON parser
    in \c{three.js}, but we will not go into its implementation details.

    \section1 Loading the Models

    First we need to initialize all array buffers for the models:

    \snippet jsonmodels/qml/jsonmodels/jsonmodels.js 1
    \dots

    Then we request the models to be loaded:

    \snippet jsonmodels/qml/jsonmodels/jsonmodels.js 2
    \dots

    Then, when the load requests return, we handle the models:

    \snippet jsonmodels/qml/jsonmodels/jsonmodels.js 3
    \dots

    Each buffer is bound and filled with the data parsed from the json models:

    \snippet jsonmodels/qml/jsonmodels/jsonmodels.js 4

    \section1 Loading the Textures

    First we create the TextureImage objects for each of the images we are
    going to load and register handlers for the \c imageLoaded and
    \c imageLoadingFailed signals. In the \c imageLoaded signal
    handlers we create the OpenGL textures:

    \snippet jsonmodels/qml/jsonmodels/jsonmodels.js 5
    \dots

    \section1 Input Handling

    First we add a MouseArea to fill the Canvas3D:

    \snippet jsonmodels/qml/jsonmodels/jsonmodels.qml 0
    \dots

    Before adding some functionality on it, we need to add properties to the
    canvas with initial values set:

    \snippet jsonmodels/qml/jsonmodels/jsonmodels.qml 1

    After that, we add rotation on mouse movement when the left mouse button
    is pressed:

    \snippet jsonmodels/qml/jsonmodels/jsonmodels.qml 2

    We need to keep the previous x and y values to avoid rotation jumping
    when the mouse button is released and pressed again. We store them in
    these properties:

    \snippet jsonmodels/qml/jsonmodels/jsonmodels.qml 3

    Then we add zooming by mouse wheel:

    \snippet jsonmodels/qml/jsonmodels/jsonmodels.qml 4

    These properties are then used in the JavaScript side when calculating
    eye/camera movement:

    \snippet jsonmodels/qml/jsonmodels/jsonmodels.js 7

    Converting the rotation values into movement is done as follows:

    \snippet jsonmodels/qml/jsonmodels/jsonmodels.js 8
*/