# State Machine Framework

![](https://1604956922-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M0-KLgOacVpbicrqehO%2F-M04eWSVrF1dPNoG3KOs%2F-M04eZA49cOiQFnwS6le%2FStateMachine.png?generation=1581716774359252\&alt=media)

State Machines provide a framework to manage the logic of an event-driven dynamic system. Many aspects of game-design/development can be modeled and implemented by state-machines. For visual novels, we can consider each Scene as a game-state, where player decisions are the events that allow change between scenes. State Machines provide a simplified perspective of a complex system, which simplifies the logic required to implement dynamic game logic.

## State Machine is a System Model

A State Machine models a complex system which is simplified according to these rules:

* There exists a finite set of well-defined states that the system can be in.  
* There exists a finite set of discrete events which can cause the system to transition into a different state
* There is a well-defined set of State-Event relationships that specify valid transitions for the system.
* Events can be considered as enternal signals that impact the system.
* It is necessary to specify the starting state of the system
* It is necessary to have program memory which maintains track of the current system state.

  We implement the StateManager class to manage the State Machine structure.

  State-Machines structure:
* a finite set of states, 
* a well-defined set of events that correspond to transitions between states 
* tracking the currently active state

  State: A State can represent a wide range of things: a scene, an animation clip, a behavior of an NPC.

Event:\
Events can be due to a variety of causes such as user input or due to gameObjects interacting with each other.

State-Event Transitions: A logical structure specifies which events cause valid transitions for each CurrentState-Event-NextState transition relationship.

### UML Class Diagrams: State-Manager System

**State-Machine Framework**

![](https://1604956922-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M0-KLgOacVpbicrqehO%2F-M04eWSVrF1dPNoG3KOs%2F-M04eZA68h2wVyeKEH6R%2FScreen%20Shot%202019-04-28%20at%2011.01.13%20AM.png?generation=1581716773650932\&alt=media)