INTRODUCTION TO
GAME CREATION
PHICS AND OTHER
OVERVIEW
• Define simulation
• Give examples of complex systems
• Distinguish between continuous and discrete event
simulation
• Explain how object-oriented design principles can
be used in building models
• Explain the additional concerns for animation versus
single images
• Describe the important issues in computer gaming
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WHAT IS SIMULATION?
•Simulation
•A model of a complex system and the
experimental manipulation of the model to
observe the results
Systems that are best suited to being simulated are
dynamic, interactive, and complicated
•Model
•An abstraction of a real system
It is a representation of the objects within the
system and the rules that govern the interactions of
the objects
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CONSTRUCTING MODELS
•Discrete event simulation
•Made up of entities, attributes, and events
• Entity The representation of some object in the real system
that must be explicitly defined
• Attribute Some characteristic of a particular entity
• Event An interaction between entities
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GRAPHICS
•Graphics
•Originally the language of communications
for engineers, designers, and architects
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Computer-aided design (CAD)
•A system that uses computers with advanced
graphics hardware and software to create
precision drawings or technical illustrations
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GRAPHICS
Figure 14.3 Geometric modeling techniques
A. © ArtyFree/ShutterStock, Inc.; B. © Stephen Sweet/ShutterStock, Inc.;
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GRAPHICS
Shape and surface influence an object’s
appearance
Equations used to describe planes, spheres,
and cylinders
Real world surfaces are rough, which scatter
light differently, requiring texture mapping
techniques
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GRAPHICS
Illumination model
Simulation of light interaction at one point
on an object
Shading model (shading)
Process of using an illumination model
to determine the appearance of an
entire object
Rendering
The process of creating an entire image
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COMPUTER GAMING
•Computer gaming is a simulation of a virtual
world
•Game designers must have knowledge of the
following to make people, objects, and
environments behave realistically in a virtual
world:
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Computer graphics
Artificial intelligence
Human-computer interactions and simulation
Software engineering
Computer security
Fundamentals of mathematics
Laws of physics relating to gravity, elasticity, light, and sound
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GAMEPLAY
•Gameplay: The type of interactions and
experiences a player has during the game
•Game genres, based on gameplay, include:
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Action games
Shooter games
Action-adventure games
Life-simulation games
Role-playing games
Strategy games
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CREATING THE VIRTUAL WORLD
•Game engine--a software system within
which games can be created
•Following functionality provided by tools of a
game engine:
• A rendering engine for graphics
• A physics engine to provide a collision detection
system and dynamics simulation
• A sound-generating component
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CREATING THE VIRTUAL WORLD
• Additional functionality resulting from tools of a
game engine:
•A scripting language apart from the code
driving the game
•Animation – movement given to objects
•Artificial intelligence algorithms (e.g., pathfinding algorithms)
•A scene graph that holds the spatial
representation in a graphical sense
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SOFT SKILLS
•High Quality Game Design and Development
Requires Effective Use of “Soft Skills”:
• Effective collaboration with designers, programmers,
and artists on various technical ideas throughout the
entire game design and development process
• Flexibility and adaptability as the game design
constantly evolves and changes throughout the
development and production process
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SOFT SKILLS
• Willingness to abandon much of the completed
design work when the game’s story line, mechanics,
art, programming, audio, video, and/or scripting
requires significant changes
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GAME CODE INTRODUCTION
• Used to be programmers created games
• But many great programmers not great game makers
• With budget shift, emphasis has shifted
• Game content creators are artist and designers
• Programmers can be thought of as providing
services for content
• But fate of entire game rests in their hands
PROGRAMMING AREAS – GAME CODE
• Everything directly related to game itself
• How camera behaves, score is kept, AI for bots, etc.
• Often in scripting language (rest is in C++, more
on languages next)
• Produce faster iterations
• Allow technical designers/artists to change behaviors
• More appropriate language for domain (ex: AI probably
not easiest in C++)
GAME PROGRAMMING
•After all the design decisions have been
finalized, programmers produce the code to
create the virtual world of the game
•Popular languages include: C++, Java, and
C
•Some well-established game engineers
have created custom languages based on
their games, e.g., Epic Game’s UnrealScript
for the Unreal Game
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GAME PROGRAMMING
•A variety of application programming
interfaces (APIs) and libraries are available to
help developers with key programming tasks
•The choice of API determines which
vocabulary and calling conventions the
programmer should employ to use the
services
•The target game platform determines which
service the programmer will use; some
libraries permit efficient cross-platform
development
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PROGRAMMING AREAS – GAME
ENGINE
• Support code that is not game specific
• More than just drawing pretty 3d graphics (that is actually
the graphics engine, part of the game engine)
• Isolate game code from hardware
• ex: controller, graphics, sound
• Allows designers to concentrate on game
• Common functionality needed across game
• Serialization, network communication, path-finding, collision
detection
PROGRAMMING AREAS – TOOLS
• Most involve content creation
• Level editors, particle effect editors, sound editors
• Some to automate repetitive tasks (ex: convert
content to game format)
• These usually have no GUI
• Sometimes written as plug-ins for off-the-shelf tools
• Ex: extensions to Maya or 3dStudio or Photoshop
• If no such extension available, build from scratch
PROGRAMMING TEAM ORGANIZATION
• Programmers often specialize
• Graphics, networking, AI
• May be generalists, know something about
everything
• Often critical for “glue” to hold specialists together
• Make great lead programmers
• More than 3 or 4, need some organization
• Often lead programmer, much time devoted to
management
• More than 10 programmers, several leads (graphics
lead, AI lead, etc.)
THE GAME DESIGN
• The Game Design Bible
• Story
• Gameplay
• Interface
• The Art Bible
• The Software Bible
EVALUATION
Game Design
Evaluation
Development
DEVELOPMENT
Coding and
Debugging
Testing
Release
TYPICAL DEVELOPMENT CYCLE
Idea
Proposal
Design
Evaluation
Coding
Testing
Release
SOFTWARE METHODOLOGIES
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Code and Fix
Waterfall
Iterative
Agile
SPIRAL DEVELOPMENT CYCLE
Design
Coding
and Art
Start
Evaluation
Release
Testing
METHODOLOGIES – CODE AND FIX
• Really, lack of a methodology
• And all too common
• Little or no planning, diving
straight into implementation
• Reactive, no proactive
• End with bugs. If bugs faster
than can fix, “death spiral” and
may be cancelled
• Even those that make it, must
have “crunch time”
• viewed after as badge of
honor, but results in burnout
METHODOLOGIES - WATERFALL
• Plan ahead
• Proceed through various planning steps before
implementation
• requirements analysis, design, implementation, testing
(validation), integration, and maintenance
• The waterfall loops back as fixes required
• Can be brittle to changing functionality,
unexpected problems in implementation
• Going back to beginning
WATERFALL DEVELOPMENT CYCLE
Idea
Proposal
Design
Evaluation
Coding
Testing
Release
METHODOLOGIES - ITERATIVE
• Develop for a period of time (1-2 months), get
working game, add features
• Periods can coincide with publisher milestones
• Allows for some planning
• Time period can have design before implementation
• Allows for some flexibility
• Can adjust (to new technical challenges or producer
demands)
METHODOLOGIES - AGILE
• Admit things will change, avoid looking too far in
the future
• Value simplicity and the ability to change
• Can scale, add new features, adjust
• Relatively new for game development
• Big challenge is hard to convince publishers
ITERATIVE AND AGILE METHODS
Proposal
Design and
initial prototype
Refine Prototype
Until Acceptable
Release
COMMON PRACTICES – VERSION
CONTROL
• Database containing files and past history of them
• Central location for all code
• Allows team to work on related files without
overwriting each other’s work
• History preserved to track down errors
• Branching and merging for platform specific parts
COMMON PRACTICES – QUALITY (1 OF
2)
• Code reviews – walk through code by other
programmer(s)
• Formal or informal
• “Two eyes are better than one”
• Value is programmer aware others read
• Asserts
• Force program to crash to help debugging
• Ex: Check condition is true at top of code, say pointer not NULL
before following
• Removed during release
COMMON PRACTICES – QUALITY (2
OF 2)
• Unit tests
• Low level test of part of game (Ex: see if physics computations
correct)
• Tough to wait until very end and see if bug
• Often automated, computer runs through combinations
• Verify before assembling
• Acceptance tests
• Verify high-level functionality working correctly (Ex: see if levels
load correctly)
• Note, above are programming tests (ie- code, technical). Still
turned over to testers that track bugs, do gameplay testing.
• Bug database
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Document and track bugs
Can be from programmers, publishers, customers
Classify by severity
Keeps bugs from falling through cracks
Helps see how game is progressing
DESIGN TO SCHEDULE
Idea
Proposal
Design
Evaluation
High Priority Code
Run out of time
and money
Med High Priority Code
Release
Med Priority Code
Med Low Priority Code
Low Priority Code
GAME PROGRAMMING
•Coding process begins with the creation of
“the game loop”
•Game loop is responsible for managing the
game world, regardless of any input from the
user
•For example, the game loop might update
enemy movement in the game or check for
victory/loss conditions
•Basically, the game loop manages the
simulation
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GAME PROGRAMMING
•Collaborating effectively is essential to
creating a streamlined, “killer” computer
game
•Collaboration and cooperation will be
necessary because, despite beta testing
and demoing, invariably bugs may begin to
adversely effect the operation of the game
•If it is an online game you helped develop,
you will be able to perform any fixes without
having to interrupt the ongoing action or
force the company to order a costly recall
of the game
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