UniRx — PowerObservables

Prerequisites

Familiar with Observer pattern
Hands on any Rx library

Introduction

PowerObservables are set of time-based operations with ability to pause and possibility to manage tick freqeuency

Why Power Observables

Easy access to time-based operations
Timers / Countdowns based on TimeSpans
Ability to pause an observable using another observable (i.e. BoolReactiveProperty)

Power Observables

Countdown

Observable sequence that produces a differed time value for certain duration with ability to pause and resume. Completes when there is no time left.

It’s pretty usefull when it comes to

Limit time in Arcade Games
Countdown before race start when you want to prompt “3, 2, 1, GO”
Damage overtime — every tick deal 10 damage to player, on complete remove debuff

PowerObservable
	.Countdown(Time)
	.Subscribe(OnTick, OnComplete)
	.AddTo(this);

Sequence: Countdown(3) → 2 → 1 → done with 3rd tick

TimerInterval

Observable sequence that produces a value after each period for certain duration with ability to pause.

PowerObservable
	.TimerInterval(Time)
	.Subscribe(OnTick, OnComplete)
	.AddTo(this);

Sequence: TimerInterval(3) → 1 → 1 → done with 3rd tick

CountedInterval

Returns an observable sequence with aggregated time since subscribe with pause option

PowerObservable
	.TimerInterval(Time)
	.Subscribe(OnTick, OnComplete)
	.AddTo(this);

Sequence: CountedInterval() → 1 → 2 → 3 → 4 → 5…

TimerCountedInterval

Returns an observable sequence with aggregated time since subscribe. Lasts for certain duration. It’s the same concept as Countdown but reversed. Instead times go up from zero. It completes after certain duration.

PowerObservable
	.TimerInterval(Time)
	.Subscribe(OnTick, OnComplete)
	.AddTo(this);

Sequence: TimerCountedInterval(3) → 1 → 2 → done with 3rd tick

How To Use

Simple use case scenario below:

var pause = new BoolReactiveProperty(); // create UniRx ReactiveProperty to manage pause

PowerObservables
	.CountedInterval(pause, tick: 1f) // you can provide the freqeuency of ticks
	.Subscribe(time => 	
	{ 
		// every tick 
		// 00:00 ...
		// 00:01 ...
		// 00:02
	})
	.AddTo(this); 

pause.Value = true; // interval will stops
pause.Value = false; // interval will resume from previous point

Unity Installation

Since unity doesn’t support git dependencies in package.json you have to install UniRx manually. Edit manifest.json file in your Unity Packages directory

{
	"dependencies": {
		"com.gbros.tools.unirx.powerobservables": "[<https://github.com/GbrosGames/Tools.git?path=Assets/UniRx/PowerObservables>](<https://github.com/GbrosGames/Tools.git?path=Assets/UniRx/PowerObservables>)",
		"com.neuecc.unirx": "[<https://github.com/neuecc/UniRx.git?path=Assets/Plugins/UniRx/Scripts>](<https://github.com/neuecc/UniRx.git?path=Assets/Plugins/UniRx/Scripts>)"
	}
}

Unity Examples

All code samples can be found on our GitHub page

Example 1 - Counted Interval

This example shows how to create Interval observable that will return TimeSpan in the cumulative way. It shows the way of refreshing the UI. It also shows use case for BoolReactiveProperty from UniRx library to manage pause/resume functionality.

Example 2 — Countdown

This example shows how to create, restart and refresh Countdown and how to manage subscription and completion methods in observable.

Where To Go From Here

MessageBroker

Resources

UniRx Library