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Quickstart: Retrieving the Quaternion and rotation matrix with the Orientation sensor (C#)

Applies to Windows and Windows Phone

You can use the Orientation sensor to retrieve a Quaternion and rotation matrix with an app written in C#. Developers typically use this data to control complex games.

Roadmap: How does this topic relate to others? See: Roadmap for Windows Runtime apps using C# or Visual Basic.

The Orientation sensor returns two forms of data: a quaternion and a rotation matrix. A quaternion can be most easily understood as a rotation of a point [x,y,z] about an arbitrary axis (contrasted with a rotation matrix, which represents rotations around three axes). The mathematics behind quaternions is fairly exotic in that it involves the geometric properties of complex numbers and mathematical properties of imaginary numbers, but working with them is simple, and frameworks like DirectX support them.

A complex 3-D app can use the Orientation sensor to adjust the user's perspective. This sensor combines input from the accelerometer, gyrometer, and compass.

Objective: After completing this quickstart you will understand how to use the Orientation sensor to detect changes in movement.

Prerequisites

You should be familiar with XAML, Visual C#, and events.

The device or emulator that you're using must support an orientation sensor.

Time to complete: 20 minutes.

Instructions

1. Open Microsoft Visual Studio

Open an instance of Microsoft Visual Studio.

2. Create a new project

Create a new project, choosing a Blank App from the Visual C#/Store Apps project types.

3. Replace the C# code

Open your project's MainPage.xaml.cs file and replace the existing code with the following.



using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;

using Windows.UI.Core;
using Windows.Devices.Sensors;

// The Blank Page item template is documented at http://go.microsoft.com/fwlink/p/?linkid=234238

namespace App1
{
    /// <summary>
    /// An empty page that can be used on its own or navigated to within a Frame.
    /// </summary>
    public sealed partial class MainPage : Page
    {
        private OrientationSensor _sensor;

        private async void ReadingChanged(object sender, OrientationSensorReadingChangedEventArgs e)
        {
            await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
            {
                OrientationSensorReading reading = e.Reading;

                // Quaternion values
                txtQuaternionX.Text = String.Format("{0,8:0.00000}", reading.Quaternion.X);
                txtQuaternionY.Text = String.Format("{0,8:0.00000}", reading.Quaternion.Y);
                txtQuaternionZ.Text = String.Format("{0,8:0.00000}", reading.Quaternion.Z);
                txtQuaternionW.Text = String.Format("{0,8:0.00000}", reading.Quaternion.W);

                // Rotation Matrix values
                txtM11.Text = String.Format("{0,8:0.00000}", reading.RotationMatrix.M11);
                txtM12.Text = String.Format("{0,8:0.00000}", reading.RotationMatrix.M12);
                txtM13.Text = String.Format("{0,8:0.00000}", reading.RotationMatrix.M13);
                txtM21.Text = String.Format("{0,8:0.00000}", reading.RotationMatrix.M21);
                txtM22.Text = String.Format("{0,8:0.00000}", reading.RotationMatrix.M22);
                txtM23.Text = String.Format("{0,8:0.00000}", reading.RotationMatrix.M23);
                txtM31.Text = String.Format("{0,8:0.00000}", reading.RotationMatrix.M31);
                txtM32.Text = String.Format("{0,8:0.00000}", reading.RotationMatrix.M32);
                txtM33.Text = String.Format("{0,8:0.00000}", reading.RotationMatrix.M33);
            });
        }

        public MainPage()
        {
            this.InitializeComponent();
            _sensor = OrientationSensor.GetDefault();
 
            // Establish the report interval for all scenarios
            uint minReportInterval = _sensor.MinimumReportInterval;
            uint reportInterval = minReportInterval > 16 ? minReportInterval : 16;
            _sensor.ReportInterval = reportInterval;

            // Establish event handler
            _sensor.ReadingChanged += new TypedEventHandler<OrientationSensor, OrientationSensorReadingChangedEventArgs>(ReadingChanged);
        }
    }
}


You'll need to rename the namespace in the previous snippet with the name you gave your project. For example, if you created a project named OrientationSensorCS, you'd replace namespace App1 with namespace OrientationSensorCS.

4. Replace the XAML code

Open the file MainPage.xaml and replace the original contents with the following XML.


<Page
    x:Class="App1.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:App1"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Grid x:Name="LayoutRoot" Background="Black">
        <TextBlock HorizontalAlignment="Left" Height="28" Margin="4,4,0,0" TextWrapping="Wrap" Text="M11:" VerticalAlignment="Top" Width="46"/>
        <TextBlock HorizontalAlignment="Left" Height="23" Margin="4,36,0,0" TextWrapping="Wrap" Text="M12:" VerticalAlignment="Top" Width="39"/>
        <TextBlock HorizontalAlignment="Left" Height="24" Margin="4,72,0,0" TextWrapping="Wrap" Text="M13:" VerticalAlignment="Top" Width="39"/>
        <TextBlock HorizontalAlignment="Left" Height="31" Margin="4,118,0,0" TextWrapping="Wrap" Text="M21:" VerticalAlignment="Top" Width="39"/>
        <TextBlock HorizontalAlignment="Left" Height="24" Margin="4,160,0,0" TextWrapping="Wrap" Text="M22:" VerticalAlignment="Top" Width="39"/>
        <TextBlock HorizontalAlignment="Left" Height="24" Margin="8,201,0,0" TextWrapping="Wrap" Text="M23:" VerticalAlignment="Top" Width="35"/>
        <TextBlock HorizontalAlignment="Left" Height="23" Margin="4,234,0,0" TextWrapping="Wrap" Text="M31:" VerticalAlignment="Top" Width="39"/>
        <TextBlock HorizontalAlignment="Left" Height="28" Margin="4,274,0,0" TextWrapping="Wrap" Text="M32:" VerticalAlignment="Top" Width="46"/>
        <TextBlock HorizontalAlignment="Left" Height="21" Margin="4,322,0,0" TextWrapping="Wrap" Text="M33:" VerticalAlignment="Top" Width="39"/>
        <TextBlock x:Name="txtM11" HorizontalAlignment="Left" Height="19" Margin="43,4,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top" Width="53"/>
        <TextBlock x:Name="txtM12" HorizontalAlignment="Left" Height="23" Margin="43,36,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top" Width="53"/>
        <TextBlock x:Name="txtM13" HorizontalAlignment="Left" Height="15" Margin="43,72,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top" Width="53"/>
        <TextBlock x:Name="txtM21" HorizontalAlignment="Left" Height="20" Margin="43,114,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top" Width="53"/>
        <TextBlock x:Name="txtM22" HorizontalAlignment="Left" Height="19" Margin="43,156,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top" Width="53"/>
        <TextBlock x:Name="txtM23" HorizontalAlignment="Left" Height="16" Margin="43,197,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top" Width="53"/>
        <TextBlock x:Name="txtM31" HorizontalAlignment="Left" Height="17" Margin="43,230,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top" Width="53"/>
        <TextBlock x:Name="txtM32" HorizontalAlignment="Left" Height="19" Margin="43,270,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top" Width="53"/>
        <TextBlock x:Name="txtM33" HorizontalAlignment="Left" Height="21" Margin="43,322,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top" Width="53"/>
        <TextBlock HorizontalAlignment="Left" Height="15" Margin="194,8,0,0" TextWrapping="Wrap" Text="Quaternion X:" VerticalAlignment="Top" Width="81"/>
        <TextBlock HorizontalAlignment="Left" Height="23" Margin="194,36,0,0" TextWrapping="Wrap" Text="Quaternion Y:" VerticalAlignment="Top" Width="81"/>
        <TextBlock HorizontalAlignment="Left" Height="15" Margin="194,72,0,0" TextWrapping="Wrap" Text="Quaternion Z:" VerticalAlignment="Top" Width="81"/>
        <TextBlock x:Name="txtQuaternionX" HorizontalAlignment="Left" Height="15" Margin="279,8,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top" Width="104"/>
        <TextBlock x:Name="txtQuaternionY" HorizontalAlignment="Left" Height="12" Margin="275,36,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top" Width="108"/>
        <TextBlock x:Name="txtQuaternionZ" HorizontalAlignment="Left" Height="19" Margin="275,68,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top" Width="89"/>
        <TextBlock HorizontalAlignment="Left" Height="21" Margin="194,96,0,0" TextWrapping="Wrap" Text="Quaternion W:" VerticalAlignment="Top" Width="81"/>
        <TextBlock x:Name="txtQuaternionW" HorizontalAlignment="Left" Height="12" Margin="279,96,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top" Width="72"/>

    </Grid>
</Page>


You'll need to replace the first part of the class name in the previous snippet with the namespace of your app. For example, if you created a project named OrientationSensorCS, you'd replace x:Class="App1.MainPage" with x:Class="OrientationSensorCS.MainPage". You should also replace xmlns:local="using:App1" with xmlns:local="using:OrientationSensorCS".

5. Build, deploy and run the app

Press F5 or select Debug > Start Debugging to build, deploy, and run the app.

Once the app is running, you can change the accelerometer values by moving the device or using the emulator tools.

6. Stop the app

  1. Press ALT+Tab to return to Visual Studio.
  2. Press Shift+F5 or select Debug > Stop Debugging to stop the app.

Summary

The previous example demonstrates how little code you'll need to write in order to integrate orientation-sensor input in your app.

The app establishes a connection with the default orientation sensor in the MainPage method.


 _sensor = OrientationSensor.GetDefault();

The app establishes the report interval within the MainPage method. This code retrieves the minimum interval supported by the device and compares it to a requested interval of 16 milliseconds (which approximates a 60-Hz refresh rate). If the minimum supported interval is greater than the requested interval, the code sets the value to the minimum. Otherwise, it sets the value to the requested interval.


uint minReportInterval = _accelerometer.MinimumReportInterval;
uint reportInterval = minReportInterval > 16 ? minReportInterval : 16;
_accelerometer.ReportInterval = reportInterval;

The new sensor data is captured in the ReadingChanged method. Each time the sensor driver receives new data from the sensor, it passes the values to your app using this event handler. The app registers this event handler on the following line.


_sensor.ReadingChanged += new TypedEventHandler<OrientationSensor, 
OrientationSensorReadingChangedEventArgs>(ReadingChanged);
 

These new values are written to the TextBlocks found in the project's XAML.

Related topics

OrientationSensor class
OrientationSensor Sample
Roadmap for creating apps using C#, C++, or VB

 

 

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