Data Driven Is Half the Battle
Me
Jeff Ward
Toolsmith / Programmer
Fire Hose Games
Previously:
• Orbus Gameworks (Metrics Middleware Software / Consulting)
• Bethesda Game Studios (Oblivion / Fallout 3)
This is a talk about being data
driven in a smart way
This is not a talk about data
driven programming…
But we have to stop there on our way…
Data Driven
When a coder “clearly distinguishes code from the
data structures on which it acts, and designs both so
that one can make changes to the logic of the
program by editing not the code but the data
structure”
Data Driven
• Separating code and data
• Data is exposed and editable
• Changing data can change the logic or behavior
Benefits
• Fast iteration time for certain changes
• Ability to add and remove parts quickly
• Allow other team members to do their work
without programmer intervention
What do you Drive Via Data?
• Everything!
• Whatever is data
• Whatever people might need to change
Common Data Driven Elements
• Levels
• User Interfaces
• Stats / The Numbers
• Hit points, damage, probabilities, formulas
• AI
• What they can do, relative importance, probability
• Game Configuration
The usefulness of data driven
programming is depends on what,
how, and to whom you expose your
data
•What
•Who
•How
•
- Data Files, .INI files, Text Files, XML, Json
Usefulness
• Readable by anyone
• Editable by anyone
• Which also means being able to fix syntax errors
• Self documenting
Approaches
• Human Readable Text Files
• Xml, json, proprietary
• Binary formats
Usefulness
• Readable by anyone
• Editable by anyone
• Which also means being able to fix syntax errors
• Self documenting
“Human Readable”
“Human Readable”
“Programmer Readable”
“Programmer Understandable”
(for the most part)
Usefulness
• Readable by anyone
• Editable by anyone
• Which also means being able to fix syntax errors
• Self documenting
Explanations
• These formats are meant to be context free
• The meaning of the data is defined by the program, not
the format.
• This means that to truly understand what’s going
on, something needs to supply context
Interruptions
• 82 percent of all interrupted work is resumed on
the same day.
• It takes an average of 23 minutes and 15 seconds to
get back to the task.
• Increases stress, increases errors.
Focus on the Problem
This is the problem…
This is not a case against human
readable formats
This is a case for good tools
This is a talk about tools!
And exposing your data
Editors are the Answer
Simple Editors
This is a tech talk
(and a design talk…)
Two Sides
The Editor Side
The Game Code Side
Editor Goals
• Driven by game code
• Easy to use
• Won’t loose any data
• If you can’t get these, you aren’t doing anyone any
favors.
Game Code: Make It Easy
• The key here is programmers are lazy.
• If you make it hard to
• read / write properties to data driven files
• add properties to the editor
• document said properties
• Programmers won’t do it.
Game Code: Make It Easy
Every step you add to the process makes it more likely
that a step will be missed or preformed incorrectly
What to Strive For
•
•
•
•
Types are discoverable
Properties on types are discoverable
Documentation on properties are discoverable
(Initial) UI for editing properties is generated from
discovered properties, types, and documentation
• Serialization / deserialization occurs through this
discovery process
C# Makes It Easy
C++ Makes it Hard!
Data description formats?
Parsers?
Generators?
Custom Reflection?
“One Line Changes”
One Way How
Basis of Custom Reflection
class Version : public Reflect::ConcreteInheritor<Version, Element>
{
public:
std::string m_Source;
static void EnumerateClass( Reflect::Compositor<Version>& comp )
{
comp.AddField( &Version::m_Source, "m_Source" );
}
};
void Init()
{
Reflect::RegisterClass<Version>( "Version" );
}
Be Careful
• Relying on deserialzation of each object
• Read data that doesn’t change once
• Potentially cache other data
• Memory footprint of reflected properties
• Human readable formats are good during
development, optimized formats are better for
deployment
Summary
• Data Driven Programming is Awesome!
• So long as people can actually use it
• And understand it without interrupting others
• Tools make this possible
• Tools that modify data should be
• Easy to use
• Easy to maintain
• My recommendation is reflection
Questions?
Email: [email protected]
Blog: www.jeffongames.com
Twitter: @fuzzybinary
www.firehosegames.com
Twitter: @FireHoseGames