GeoGebra and Joystick Dr Đor đ e Herceg, Dr Dragoslav Herceg Faculty of Sciences University of Novi Sad Serbia 1

GeoGebra in Novi Sad Faculty of Sciences, University of Novi Sad Besides regular work, members of our faculty also teach in elementary and high schools Many of our graduates work as matematics teachers in schools We organize courses and meet our colleagues from schools We use and recommend GeoGebra! 2

GeoGebra institute of Novi Sad GeoGebra Institue of Novi Sad, Serbia 3

How we use GeoGebra GeoGebra is great for preparing teaching and self-study materials. It is free, easy to download and install and it speaks our language. We have developed tools for numerical mathematics Also accompanying materials for textbooks We often find it easier to “sketch” an explanation in GeoGebra, than on paper! 4

What we would like to do Learning through play We want to motivate children to learn while playing mathematical games (more on that later) We also want to provide a more direct way of manipulating geometrical drawings Especially important with younger children that cannot grasp abstract notions 5

The problem we address Once prepared, interactive drawings need user input, which is provided by typing commands, moving sliders and clicking checkboxes. 6

One parameter at a time We can only control one parameter at a time with the mouse Sliders and checkboxes on the screen are just imitations of the “real thing” Precise “aiming” at sliders and checkboxes can be problematic, particularly during talks and demonstrations 7

What we have is: 8 MOUSE

What we want is: 9

Joysticks and Gamepads They can have up to 6 axes Many buttons (typically 6-12) POV hats All of these can be used simultaneously! Gamepad 10

Why use game controllers? Benefits: ◦ Control many parameters simultaneously ◦ Inexpensive ◦ Ubiquitous ◦ Intuitive – “I push here and that thing moves” ◦ Designed to be used without looking (tactile feedback) ◦ Interesting for the kids 11

Drawbacks? Not very precise Not everybody has one Support for game controllers on various platforms and operating systems is not standardized There exist several SDKs for game controllers: ◦ DirectX (Windows, unmanaged code) ◦ SlimDX (Windows+.NET) ◦ JXInput (Java+JNI) ◦... 12

GameControllerInput (GCI) Developed in C# on.NET Uses the SlimDX library to access DirectInput/DirectX compatible game controllers Hosts GeoGebra applets inside a WebBrowser component Extendable – easy to add new mappers 13

GeoGebra applet methods In version 3.2, GeoGebra JavaScript interface provides many useful methods which provide full control over the drawings. Our program acts as a “shell” around the GeoGebra applet, which interprets input given by a game controller and maps it to parameters and object properties in a drawing. 14

Axis mapping Raw data obtained from a joystick axis is in range [0,65535] It can be mapped linearly to any given interval [a, b] However, game controllers are not precision devices. “Dead zone” must be set appropriately. Should the joystick axis map directly to a variable, or should it control the amount of change? 15

Mapping curve for axes 16

Button mapping Each button can be mapped to a command, such as: ◦ Set a value of a variable ◦ Change a value of a variable (+/-) ◦ Control visibility of objects ◦ Control trace of objects ◦ Refresh display ◦ Generate random numbers ◦ etc... 17

How it works Game controller AxisMapper ButtonMapper JavaScriptGeoGebra Input from a game controller is passed to various mappers Mappers call JavaScript methods JavaScript methods call methods of an embedded GeoGebra applet 18

Configuration Upon application start, the user assigns various mappers to game controller’s axes and buttons. A configuration is a set of all mappings for a game controller. Configurations can be saved and loaded from files. 19

Screenshots 1/2 20

Screenshots 2/2 21

DEMO 22

Conclusions Children like to experiment, especially with something they can touch Thanks to a growing list of GeoGebra applet methods, it is now possible to have almost complete control of GeoGebra from the outside When interpreted appropriately, input from gamepads and joysticks can be used to control drawings in GeoGebra So we can provide a more intuitive and less artificial way of interaction with drawings 23

Thank you! 24