UnityEngineGUILayout

UnityEngineGUILayout refers to a set of classes within the Unity game engine that facilitate the creation of user interfaces using an immediate mode GUI system. This system allows developers to draw GUI elements directly within the `OnGUI()` method of a script. The `GUILayout` class provides static methods for creating various GUI controls such as buttons, labels, text fields, and more, automatically arranging them based on their order of creation.

Unlike Unity's UGUI system, which uses a scene-based approach with GameObjects and components, `GUILayout` operates on a frame-by-frame basis. When `OnGUI()` is called, the layout engine calculates the position and size of each control. This makes it particularly useful for quick prototyping, in-game debugging tools, or simple editor extensions where performance is not a critical concern.

The `GUILayout` system automatically handles spacing and alignment, simplifying the process of building basic UIs. However, it offers less control over precise element placement compared to manual GUI positioning or UGUI. Elements are typically arranged vertically or horizontally based on the order they are added to the GUI. Developers can use `GUILayout.BeginHorizontal()`, `GUILayout.EndHorizontal()`, `GUILayout.BeginVertical()`, and `GUILayout.EndVertical()` to group controls and define their arrangement.

`GUILayout` is generally considered less performant than UGUI for complex or frequently updated interfaces. Its immediate mode nature means GUI elements are re-drawn and re-laid out every frame, which can become a bottleneck in demanding applications. Nevertheless, for specific use cases like editor tools or simple in-game menus, `GUILayout` remains a convenient and straightforward option.