Products for USB Sensing and Control
Products for USB Sensing and Control

Interactive Maze: Spatial Phidget and Unity Software

Create an interactive Unity game with the Phidget Spatial


by Ben

Introduction

Prerequisites

This project assumes you have completed the following guides:

Goal

The goal of the game is to get the ball through the maze. The orientation of the maze is directly linked to the Spatial Phidget. The maze graphic is created using the Unity Roll-a-Ball Tutorial, which should be completed before beginning this project (see prerequisites).

Hardware

Connect your Phidget Spatial to your VINT Hub, and your VINT Hub to your computer.

Interpreting Data

The Spatial Phidget's accelerometer can measure all accelerations experienced by the sensor, including the acceleration due to gravity. Because this acceleration always points down, it can be used to calculate orientation.

Read the Calculating Tilt Angles Tutorial for a detailed explanation.


Here are the relevant equations for reference:

`theta = tan^-1 (M_y/M_z) " " phi = tan^-1 (M_x/M_z)`


`theta = "roll angle "phi = "pitch angle"`
`M_x = "Measured x-axis acceleration"`
`M_y = "Measured y-axis acceleration"`
`M_z = "Measured z-axis acceleration"`

Software

Step 1: Setup

When your program starts, you need to create your accelerometer object. See the flow chart to the right for details on how to set up the accelerometer object.

                            


//create Phidget object outside of Start() so it can be used in other methods
Accelerometer accel = new Accelerometer();
    
void Start()
{
    //TODO: Address, Register for Events
    //      Open
}

For now, skip the maze creation and just have your ball on a flat surface. Generating a maze will be discussed below.

Step 2: Events

Next, you can add your events.

Attach Event

                                

void OnAttach(object sender, AttachEventArgs e)
{
    //TODO: Set data interval to minimum
}

void OnDetach(object sender, DetachEventArgs e)
{
    //TODO: Pause game 
}

void OnSpatialData(object sender, SpatialSpatialDataEventArgs e)
{
    //example of accessing acceleration data
    double xAxis = e.Acceleration[0];
    double yAxis = e.Acceleration[1];
    double zAxis = e.Acceleration[2];
    
    //TODO: Calculate tilt angles
    //store angles in variables for use in Fixed Update

}

Step 3: Main loop

Updates

Next, you can take a look at your update code. There are two used in this project:

  • Update
  • Fixed Update

Your Update code will handle things like an escape key being pressed to exit the game, or the space key being pressed to reset the ball and generate a new maze.

In your Fixed Update code, you should convert your angles and rotate your maze. This process is described in more detail below!

Mapping Tilt to the Maze

Calcluated your tilt angles using the fomula described in the previous section. The next step is converting them into a form Unity understands. Unity uses a system to describe rotations called Quaternions. You can convert your accelerometer angles to a Quaternion like so:

                            
    
    void FixedUpdate()
    {
        //Convert accelerometer angles to quaternion format
        Quaternion target = Quaternion.Euler(/*pitch angle here (in DEGREES)*/, 0, /*roll angle here (in DEGREES)*/);
        //TODO: Rotate table to match accelerometer      
    }
    
    


Hint: Check out the Slerp function on the Unity API if you are stuck.


Reaching Goal

When the ball reaches the goal, you will need to end the game and print a win statement. For bonus points, you could try having multiple levels of increasing maze difficulty. When the goal is reached, the level is passed and the next stage is generated.

Closing Application

As always, you will want to properly close your Phidget objects when an application ends. Add the following Unity method to your code:


void OnApplicationQuit()
{
    //TODO: Close Phidget object
}

Step 4: Finishing Your Game

After making sure the maze tilts properly, the game is almost complete. Any good maze needs walls to complete it and here are two ways to go about it.

By using an automated system, users can reset their ball and generate new mazes by simply pressing the space bar.

Three randomly generated mazes.

Tinkering

To put the final touches on the game, try tinkering with the physics options. Changing gravity and the angular drag on the ball can change the responsiveness of the system. Additionally, it can be helpful to spawn the player ball a bit above the maze's surface to ensure it does not fall through or stick to the surface.

mazegif

Conclusion

You now have a maze that is controled by a Spatial Phidget! With this project, you combined graphics generated through Unity and user data input from your Phidget to create an interactive game.

Check out these other projects that use Unity:

If you have any suggestions for future Phidgets Education projects, let us know at education@phidgets.com

These materials are not sponsored by or affiliated with Unity Technologies or its affiliates. “Unity” is a trademark or registered trademark of Unity Technologies or its affiliates in the U.S. and elsewhere.