- Qt 5.5
- Qt Canvas 3D
- Interaction Example
- Qt 5.5.1 Reference Documentation

# Interaction Example

The Interaction Example concentrates on the interaction between Qt Quick Controls and the objects displayed in Canvas3D. This also demonstrates drawing the same object in three different ways.

## The Controls

First, we need to import Qt Quick Controls and Layouts:

    import QtQuick.Controls 1.0
    import QtQuick.Layouts 1.0

Then, we add a RowLayout to the main component to easily add the controls side-by-side:

    RowLayout {
        id: controlLayout
        spacing: 5
        x: 12
        y: parent.height - 100
        width: parent.width - (2 * x)
        height: 100
        visible: true

And then we add three sliders to the layout. Here's the one for controlling x-axis rotation:

    Slider {
        id: xSlider
        Layout.alignment: Qt.AlignLeft
        Layout.fillWidth: true
        minimumValue: 0;
        maximumValue: 360;
        onValueChanged: canvas3d.xRotSlider = value;
    }

## Interaction

First we need to define some properties in the Canvas3D for the rotations:

    property double xRotSlider: 0
    property double yRotSlider: 0
    property double zRotSlider: 0

The `onValueChanged` signal handlers of the Slider components are connected to the above properties. Here's the connection in x-rotation slider as an example:

    onValueChanged: canvas3d.xRotSlider = value;

Then, on the JavaScript side, we just use the Canvas3D properties directly when setting the modelview matrix rotations:

    mvMatrix = mat4.rotate(mvMatrix, mvMatrix, degToRad(canvas.xRotSlider), [1, 0, 0]);
    mvMatrix = mat4.rotate(mvMatrix, mvMatrix, degToRad(canvas.yRotSlider), [0, 1, 0]);
    mvMatrix = mat4.rotate(mvMatrix, mvMatrix, degToRad(canvas.zRotSlider), [0, 0, 1]);

## Three Ways of Drawing

The actual drawing is no different from any situation where the same object is drawn multiple times. Only in this case we use a different drawing mode for each:

    gl.drawElements(gl.TRIANGLES, theModel.count, gl.UNSIGNED_SHORT, 0);
    ...
    gl.drawElements(gl.POINTS, theModel.count, gl.UNSIGNED_SHORT, 0);
    ...
    gl.drawElements(gl.LINES, theModel.count, gl.UNSIGNED_SHORT, 0);

Files:

- canvas3d/interaction/qml/interaction/interaction.js
- canvas3d/interaction/qml/interaction/main.qml
- canvas3d/interaction/main.cpp
- canvas3d/interaction/interaction.pro
- canvas3d/interaction/interaction.qrc