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Unity Engine

state

Gets or sets the full internal state of the random number generator.
Read time 2 minutesLast updated 9 hours ago

Definition

  • Type: Property
  • Namespace: UnityEngine
  • Assembly: UnityEngine.CoreModule
public static Random.State state { get; set; }

Remarks

This property can be used to save and restore a previously saved state of the random number generator. Note that 
state
is serializable, so that determinism can be preserved across sessions. Determinism is an important trait in many scenarios, such as multiplayer games, reproducible simulations, and unit testing.
Generator state can be (re)-initialized in two ways:
  1. Call Random.InitState with a simple integer "seed". This is a one-way operation and cannot be retrieved.
  2. Setting Random.state using a Random.State previously retrieved from this same property. This type cannot be constructed by the user.
See the following example for an explanation of how these work.
using UnityEngine;public class ExampleClass : MonoBehaviour{    void Start()    {        const int initialSeed = 1234;        Random.InitState(initialSeed); // cannot be retrieved        PrintRandom("Step 1");        PrintRandom("Step 2");        Random.State stateBeforeStep3 = Random.state; // can be serialized        PrintRandom("Step 3");        PrintRandom("Step 4");        Random.state = stateBeforeStep3;        PrintRandom("Step 5");        PrintRandom("Step 6");        Random.InitState(initialSeed);        PrintRandom("Step 7");        PrintRandom("Step 8");    }    static void PrintRandom(string label) =>        Debug.Log($"{label} - RandomValue {Random.Range(0, 100)}");}/*Output:Step 1 - RandomValue 38Step 2 - RandomValue 76Step 3 - RandomValue 69Step 4 - RandomValue 11Step 5 - RandomValue 69Step 6 - RandomValue 11Step 7 - RandomValue 38Step 8 - RandomValue 76*/
The values from step 5 and 6 will be equal to those from step 3 and 4 because the internal Random.state of the generator was restored to what we saved in 
stateBeforeStep3
. Also, the values from step 7 and 8 will be equal to those from step 1 and 2 because we are resetting the generator state with 
initialSeed
via Random.InitState, which leaves the generator in the exact same state as right before step 1.