This article by Venita Pereira, the author of the book Learning Unity 2D Game Development by Example, teaches us all about the various input types and states of a game. We will then go on to learn how to create buttons and the game controls by using code snippets for input detection.

"Computers are finite machines; when given the same input, they always produce the same output."

– Greg M. Perry, Sams Teach Yourself Beginning Programming in 24 Hours

(For more resources related to this topic, see here.)

Overview

The list of topics that will be covered in this article is as follows:

• Input versus output
• Input types
• Output types
• Input Manager
• Input detection
• Buttons
• Game controls

Input versus output

We will be looking at exactly what both input and output in games entail. We will look at their functions, importance, and differentiations.

Input in games

Input may not seem a very important part of a game at first glance, but in fact it is very important, as input in games involves how the player will interact with the game. All the controls in our game, such as moving, special abilities, and so forth, depend on what controls and game mechanics we would like in our game and the way we would like them to function.

Most games have the standard control setup of moving your character. This is to help usability, because if players are already familiar with the controls, then the game is more accessible to a much wider audience. This is particularly noticeable with games of the same genre and platform.

For instance, endless runner games usually make use of the tilt mechanic which is made possible by the features of the mobile device. However, there are variations and additions to the pre-existing control mechanics; for example, many other endless runners make use of the simple swipe mechanic, and there are those that make use of both.

When designing our games, we can be creative and unique with our controls, thereby innovating a game, but the controls still need to be intuitive for our target players. When first designing our game, we need to know who our target audience of players includes. If we would like our game to be played by young children, for instance, then we need to ensure that they are able to understand, learn, and remember the controls. Otherwise, instead of enjoying the game, they will get frustrated and stop playing it entirely.

As an example, a young player may hold a touchscreen device with their fingers over the screen, thereby preventing the input from working correctly depending on whether the game was first designed to take this into account and support this.

Different audiences of players interact with a game differently. Likewise, if a player is more familiar with the controls on a specific device, then they may struggle with different controls. It is important to create prototypes to test the input controls of a game thoroughly. Developing a well-designed input system that supports usability and accessibility will make our game more immersive.

Output in games

Output is the direct opposite of input; it provides the necessary information to the player. However, output is just as essential to a game as input. It provides feedback to the player, letting them know how they are doing. Output lets the player know whether they have done an action correctly or they have done something wrong, how they have performed, and their progression in the form of goals/missions/objectives.

Without feedback, a player would feel lost. The player would potentially see the game as being unclear, buggy, or even broken. For certain types of games, output forms the heart of the game.

The input in a game gets processed by the game to provide some form of output, which then provides feedback to the player, helping them learn from their actions. This is the cycle of the game's input-output system.

The following diagram represents the cycle of input and output:

Input types

There are many different input types that we can utilize in our games. These various input types can form part of the exciting features that our games have to offer. The following image displays the different input types:

The most widely used input types in games include the following:

• Keyboard: Key presses from a keyboard are supported by Unity and can be used as input controls in PC games as well as games on any other device that supports a keyboard.
• Mouse: Mouse clicks, motion (of the mouse), and coordinates are all inputs that are supported by Unity.
• Game controller: This is an input device that generally includes buttons (including shoulder and trigger buttons), a directional pad, and analog sticks. The game controller input is supported by Unity.
• Joystick: A joystick has a stick that pivots on a base that provides movement input in the form of direction and angle. It also has a trigger, throttle, and extra buttons. It is commonly used in flight simulation games to simulate the control device in an aircraft's cockpit and other simulation games that simulate controlling machines, such as trucks and cranes. Modern game controllers make use of a variation of joysticks known as analog sticks and are therefore treated as the same class of input device as joysticks by Unity. Joystick input is supported by Unity.
• Microphone: This provides audio input commands for a game. Unity supports basic microphone input. For greater fidelity, a third-party audio recognition tool would be required.
• Camera: This provides visual input for a game using image recognition. Unity has webcam support to access RGB data, and for more advanced features, third-party tools would be required.
• Touchscreen: This provides multiple touch inputs from the player's finger presses on the device's screen. This is supported by Unity.
• Accelerometer: This provides the proper acceleration force at which the device is moved and is supported by Unity.
• Gyroscope: This provides the orientation of the device as input and is supported by Unity.
• GPS: This provides the geographical location of the device as input and is supported by Unity.
• Stylus: Stylus input is similar to touchscreen input in that you use a stylus to interact with the screen; however, it provides greater precision. The latest version of Unity supports the Android stylus.
• Motion controller: This provides the player's motions as input. Unity does not support this, and therefore, third-party tools would be required.

Output types

The main output types in games are as follows:

• Visual output
• Audio output
• Controller vibration

Unity supports all three.

Visual output

The Head-Up Display (HUD) is the gaming term for the game's Graphical User Interface (GUI) that provides all the essential information as visual output to the player as well as feedback and progress to the player as shown in the following image:

HUD, viewed June 22, 2014, http://opengameart.org/content/golden-ui

Other visual output includes images, animations, particle effects, and transitions.

Audio

Audio is what can be heard through an audio output, such as a speaker, to provide feedback that supports and emphasizes the visual output and, therefore, increases immersion. The following image displays a speaker:

Speaker, viewed June 22, 2014, http://pixabay.com/en/loudspeaker-speakers-sound-music-146583/

Controller vibration

Controller vibration provides feedback for instances where the player collides with an object or environmental feedback for earthquakes to provide even more immersion as in the following image:

Having a game that is designed to provide output meaningfully not only makes it clearer and more enjoyable, but can truly bring the world to life, making it truly engaging for the player.