Programming Overview

This article describes ways of creating projects in Unigine.

The main purpose of the article is to provide insight into setting up the development environment and give the overview of programming. It contains links to other articles that help you to prepare the development environment, choose the language to programming and so on.

To create your own project with Unigine, you can use the following programming languages:

• UnigineScript
• C++, by using C++ API
• C#, by using C# API

UnigineScript can be easily extended through the Unigine API. The Unigine engine enables exporting the C++ and C# code and vice versa. You can write some functionality by using the C++ or C# language, and export it to the UnigineScript. See usage examples articles of C++ API and C# API to know more.

Unigine supports the following platforms:

• Windows (10/11)
• Linux (kernel 4.19+)

A 64-bit system is required to develop applications using UNIGINE 2 SDK. The engine fully and efficiently uses multi-core CPU architecture.

With Unigine you can build applications for these platforms with a single codebase.

Read more about the Hardware Requirements.

You can use any of these PC platforms to write your Unigine-powered project:

• Windows
• Linux

In addition to UNIGINE SDK, each platform requires specific software that you need to install in order to start coding. You can find requirements for each platform here:

• development for Windows
• development for Linux

Unigine's Application Logic System has three main concepts of logic:

• System logic - the logic of the application. You can implement your logic that will be performed during application life cycle. Your custom logic can be put in the system script file (by using UnigineScript API only), or you can inherit SystemLogic class and implement your logic (C++ and C# APIs).
  

  UnigineScript unigine.usc system script file is created automatically in the your project's folder. When you create a new C++ / C# project, it has already inherited system logic class with implemented methods to put your logic code inside.

• World logic - the logic of the world - here you should put the logic of the virtual scene. The logic takes effect when the world is loaded. You can put your logic inside the world script file (by using UnigineScript API only), or you can inherit WorldLogic class and implement your logic (C++ and C# APIs).
  

  The world script *.usc file is automatically created with the new world and has the name of your project. When you create a new C++ / C# project, it has already inherited world logic class with implemented methods to put your logic code inside.

• Editor logic - this component is to be used in case you need to implement your own Editor. It has more implemented methods providing you with clear understanding of the current Engine events (a node has been created, a property has been deleted, a material has been changed, etc.). You can inherit EditorLogic class and implement your logic in C++ or C#.
  Default UnigineScript logic for the Editor is loaded from the editor2/editor.usc file stored inside editor2.ung. You can override this UnigineScript logic file by creating a folder named editor2 in your data folder and putting there the editor.usc file with the following code (you can modify this script, but do not remove existing include lines as they are required for Editor operation):

  editor.usc

  Source code

  #include <editor2/editor_tracker.h>
  #include <editor2/editor_video_grabber.h>
  
  int init() {
  	return 1;
  }
  
  int update() {
  	return 1;
  }
  
  int shutdown() {
  	return 1;
  }

  When you create a new C++ / C# project, it has already inherited editor logic class with implemented methods to put your logic code inside.

The UNIGINE engine internal code and the application logic are executed in the pre-defined order:

1. Initialization. During this stage, the required resources are prepared and initialized. As soon as these resources are ready for use, the engine enters the main loop.
2. Main loop. When UNIGINE enters the main loop, all its actions can be divided into three stages, which are performed one by one in a cycle:
   1. Update stage containing all logic of your application that is performed every frame
   2. Rendering stage containing all rendering-related operations, physics simulation calculations, and pathfinding
   3. Swap stage containing all synchronization operations performed in order to switch between the buffers

   This cycle is repeated every frame while the application is running.

3. Shutdown. When UNIGINE stops execution of the application, it performs operations related to the application shutdown and resource cleanup.

Read this article to know where to put your logic code.

Also, read the Execution Sequence and Logic System articles to know the detailed workflow of the Unigine engine.

For an object to be conveniently integrated into application logic, it is required to specify the set of user-defined parameters and the way the object will behave and interact with other objects and the scene environment.

Depending on the programming language selected in UNIGINE, you also define the way you are going to apply the logic to objects:

• By assigning C# components, which are the part of C# Component System (.NET) enabled by default and integrated into the UnigineEditor. It is the easiest way to implement your application logic: all parameters and logic are added to components that can be assigned to any node to be executed.
• By assigning properties (for C++). Properties can be used on their own for accessing nodes and files or as an integral part of C++ Component System to extend the functionality of nodes. While the property represents a tag for logic and provides a set of user-defined parameters, the logic component integrates a node, a C++ class, containing logic implementation, and a property.

To learn more on the usage of Component Systems, see the following usage example articles:

• Using C# Component System
• Using C++ Component System

Interactions between objects can be processed using Intersections. Intersection is a shared point of the defined area (or line) and an object. Unigine has different methods to detect intersections.

There are three main types of intersections:

• World intersection - an intersection with objects and nodes.
• Physics intersection - an intersection with shapes and collision objects.
• Game intersection - an intersection with pathfinding nodes like obstacles.

There are three sections with usage example samples:

• UnigineScript Sample
• C++ Sample
• C# Sample

The programming code is the same for all supported platforms, the difference is in compiling.

For all of these samples we create new projects by using Project Generator. Project Generator creates a new world with the World Light source and the plane mesh.