How to create a loading scene in Unity

When the GameOver cut scene is triggered, the UI will show 2 buttons: Restart and Quit

Restart scene

• Create a UIManager script with a singleton
• Import UnityEngine.SceneManagement
• Create a method, for example, public void RestartGame()
• In the method, call SceneManager.LoadScene(“… scene name …”). In this case, the scene’s name is Main1
• Select the Restart button, Add a new OnClick event
• Drag and drop UIManager gameobject into the bottom left slot
• In the drop down list that says No Function, select UIManager/Restart()

Quit

• Create a method, for instance, public void QuitGame()
• In it, call Application.Quit()
• Add the method to the button as described for the Restart button

Adding scenes to Build settings

• Go to File/Build settings
• Add the scenes manually (drag and drop) or click on Add Open Scenes

Loading bar

• Create a new scene called LoadingScreen
• Create 2 UI images: Background and Progress_bar
• Add the images. Also you can add an overlay image

• Set the image type to filled and Fill Method to Horizontal

Asynchronous operation

an AsyncOperation in Unity is a coroutine. It has a property float called progress. The documentation says:

This returns how close the operation is to finishing. The operation is finished when the progress float reaches 1.0 and isDone is called

Why is it useful?
When playing videogames, some scenes take some seconds to load, so it is good to show a temporary scene while the new scene finishes loading

Implementation

• Change the scene to load in MainMenu script to LoadingScreen
• Add the scenes to the Build settings, preferably the first one at the top, in descending order (just a good practice)

Code

private Image progressBar
private void Start() => StartCoroutine(LoadProgressAsync());
private IEnumerator LoadProgressAsync()
{
    AsyncOperation asyncLoad = SceneManager.LoadSceneAsync(gameScene);
    
    while (!asyncLoad.isDone) // while loading isn't finished
    {
        // progress bar fill amount = operation progress
        progressBar.fillAmount = asyncLoad.progress;

        yield return new WaitForEndOfFrame();
    }
}