1. ITB/ITN751 Games Production Lecture 5 Game Engine Programming
Ross Brown

2. Lecture Contents Game Engine Programming
Guest Lecture – Lachlan Bland, THQ

3. Readings Textbook Chapters: Websites: Chapter 7
- a programmers view of game programming skills
– nice reference for the assignment
- some wage issues covered here

4. Bigger, better, faster, stronger
“Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning” - Rick Cook

5. Havok Euphoria Engine Software

6. Game Engine Programming
This is the first lecture on a programming role within the game industry
Game Engine development is one of the basic jobs within the computer games industry…maybe the oldest
Argument: it predates graphics technology, so text-based art free games were still programmed

7. What is a Game Engine?
Underlying software technology that supports the execution of the game
Contains a number of software modules (amongst others) integrated together to provide the gaming experience:
Graphics
Physics
Sound
Scripting
Animation
Artificial Intelligence
Networking
User Interface

8. Game Engine Overview Game Engine Audio AI Physics Game Content Scene
Graphics
Scene
Graph
User
Interface

9. Game Engines Developed to abstract away underlying aspects of a game
Enables reuse of code
Facilitates porting code to other hardware platforms

10. Graphics Module
Provides an abstraction of the Graphics Processing Unit (GPU) in the hardware
Provides the ability to render the geometric content created by artists at the highest level of fidelity possible
Incorporates advanced real-time mathematical models of how light interacts with the surface of an object
Modern GPUs are programmable allowing for very sophisticated effects

11. Graphics
Sprites
Sprites
Surface Materials
Shadows
Bloom
Bump Mapping

12. Physics Model
Implements Newtonian model of physics for the game environment objects
Gives the game object’s mass, force and velocity and uses collision detection methods to provide animation
Often uses simplifications of physics models to simulate the physics in order to provide real-time responses

13. Sumotori Dreams Simple physics demo Fits into 96k Illustrates:
Simple physics demo
Fits into 96k
Illustrates:
Collision Detection
Animations
Newtonian Physics
Rag Doll Physics

14. Sound Module
Manages the components of the soundtrack content developed by musicians and sound designers
Executes sounds based on triggers in the environment from explicit execution, time events or interactions between game objects – eg. collisions

15. Scripting
A language add-on to the engine that exposes internal engine architecture
Allows designers to glue the game together by implementing the gameplay mechanics for events, AI, rewards, etc.

16. Animation
Data structures are provided to manage and support hierarchical rigging and to animate the scripts stored from mocap and animations hard coded by the animators
The animation system needs to blend between the various canned animations and the physics interactions

17. Artificial Intelligence
Provides finite state automata and a behaviour model for the agents in the game to behave
Also provides facilities for learned behaviours – Neural Networks
Group behaviours (swarming), predator (seek), prey (flee) behaviours
Path finding is another included component for Non-Player Character (NPCs) to find their way around a game environment

18. Artificial Intelligence
Neural Network
Seek and Flee Behaviour
Finite State Automata
Flocking

19. Networking
Software to support network connections to other clients on a network or to servers
Used to maintain verified game state on any machine connected to the server
Sophisticated caching software is used to make sure every node is made aware of the present state of the game

20. Scene Graph Tree data structure used to store the content
Is operated upon by the Artificial Intelligence and Physics modules to update its state
Fed to Graphics Module to be rendered (drawn) into the framebuffer (screen memory)

21. Scene Graph Above shows a simple example of a scene graph for a robot

22. Game Loop While user input not exit Endwhile
Update Scene-Graph with network cache
Update Scene-Graph via AI
Update Scene-Graph via Physics and Animation
Render Scene-Graph to Screen via Graphics System
Endwhile

23. Game Engine is Real-time
All of this has to be updated at ~30 frames per second for a game
Thus entire loop must run in 1/30th second or less for high quality animation rates
Thus a very tight real-time system
Thus programmer skills MUST be at a high level

24. Game Engine Developer Programs the Game Engine
Programs one or multiple modules in the engine
Tends to be a specialist in one area
Usually the best programmers in the shop

25. Roles Engine Development Engine Research and Development
Cross Platform Development
Bug fixing with Quality Assurance (QA)

26. Roles Work with a lead developer in a development team
Works with technical director who oversees a number of projects
Work with animators and designers to negotiate technical requirements for the game

27. Skillset
High level Software Engineering skills – specification, testing, documentation skills
Deep understanding of basic computer science algorithms – hashing, data structures, pointer arithmetic, code optimisation (necessary)
C++ a necessity

28. Skillset
Usual analytical skills required from general ICT programming for specification/understanding of program design
Problem solving skills – creative solutions and or bug fixing
Mathematics, Physics and AI skills very desirable

29. Skillset
Multiprocessor programming – concurrant programming of multiple threads (mini programs) - for the new multicore Xbox, PC and PS3s
Do lots of development of your own mods - good
Development of deep technical skills via creation of your own engine components
People skills – yep, that again

30. Development Tools Interactive Development Environments (IDE)
Visual Studio, Eclipse…
Sophisticated environments for the development of software:
Intelligent Editors – think word processor for source code
Debuggers – allows you to watch the code execute to find problems (bugs)
Profilers – enables analysis of the efficiency of developed code

31. Development Tools Application Programming Interfaces (APIs)
Libraries of useful code to use within into your source code
DirectX – graphics/audio
OpenGL – graphics
Open Audio – audio
Middleware – useful software APIs that facilitate various smaller tasks in games (goes between other components)
Physics, Data Processing, Networking, AI, User Interfaces
Goto:

32. Console/Handheld Development Tools
Console/Handheld Development Kits
To develop for a console or handheld device – X360, PS3, DS, PSP
Specially manufactured hardware is used to communicate via a network link
Aug. 2006, PS3 Dev. Kit

33. Console/Handheld Development Tools
Remotely debug software on device
Consoles only run signed code, so need dev. kit hardware for unsigned code
Code is then given signature which runs on normal consoles

34. Some Commercial Games Engines
Gamebryo – classed as a middleware game engine solution
Unreal – full engine with tools and scripting interface for game development
Half Life 2 Source Engine – C++ engine with toolset

35. Some Free Game Engines
XNA Game Studio Express – free proprietary game engine and development environment
Irrlicht – free open source game engine

36. Guest Lecturer
Lachlan Bland – Engine Programmer
THQ Studios

37. References
Eberly, David H., 3D Game Engine Architecture: Engineering Real-Time Applications with Wild Magic, 2004 – Available online at QUT Library
Eberly, David H., Title3D game engine design : a practical approach to real-time computer graphics, Morgan Kaufmann, 2001