an introduction to procedural content generation

Pier Luca Lanzi e Michele Pirovano – Codemotion Milan

November 2014

Introduction to Procedural

Content Generation


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What is Procedural Content Generation?

Procedural Generation

with no or limited human intervention, algorithmically

of Content

of “things that affect the gameplay”, not non-player

character behavior, not the game engine


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so what exactly is procedurally generated?

levels, tracks, maps, terrains, dungeons, puzzles,

buildings, trees, grass, fire, plots, descriptions,

scenarios, dialogues, quests, characters, rules,

boards, parameters, camera viewpoint, dynamics,

weapons, clothing, vehicles, personalities, etc.


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http://en.wikipedia.org/wiki/Rogue_(video_game)#mediaviewer/File:Rogue_Screen_Shot

_CAR.PNG


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BBC Micro – 2 MHz MOS Technology 6502/6512

16-128 kB RAM 32-128 kB ROM


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https://www.youtube.com/watch?v=ISR4ebdGlOk


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What the ingredients?

domain knowledge

artificial intelligence

structured randomness

multi-layering

filters, limits & restrictions

specialized algorithms

gameplay integration


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Ingredients #1 & #2

Domain Knowledge & Artificial

Intelligence• Domain Knowledge

To generate something you need to know it

PCG typically aims at building an artificial level

designer, usually needs domain knowledge

about level design

• Artificial Intelligence

Need algorithms that can work on complex

knowledge and generate plausible content

Search-based methods, L-systems, evolutionary

computation, fractals, cellular automata,

agent-based methods, planning, etc.

11


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ingredient #3

structured randomness

things look like they have been randomly

generated but it is not completely at

random!


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f(x) = sin(x)


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they both look like “noise”

but one of them feels like it has structure…

it is structured randomness


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ingredient #4

multi-layering

typically more layers of procedural

content generation are applied in sequence


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• Warzone 2100

Heights &

Cliffs

Roads

Textures

Player Bases

Local

Features• Civilization 4

Fractal

Heightfield

Plate Tectonics

Tile Types

Rivers and Lakes

Map Bonuses


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ingredient #5

Filters, Limits & Restrictions

“In Civ3 I would say we even shipped with a sub-standard

resource

placement algorithm where all the iron could be

concentrated in just

a few small locations on the map, and for one player there

may be literally no way for them to build swordsmen.”

– Soren Johnson

"With Civ4 we instituted randomness with limitations.

There

always has to be a minimum distance between each

element of


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ingredient #6

specialized algorithms

placing special items, requires special

tricks

this tricks must be encoded in the PCG


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1. Connect all bases, the

resources,

pick three random points and

connect them

2. Apply a customize A* heuristic

and reuse roads!

3. Customize A* heuristic with

randomize cost of non-road

grid cells.


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ingredient #7

gameplay integration

Is it fun to play? Is the progression

adequate?


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is this all there is?


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PC

G

Is it done online?

Or offline?

Is it necessary

content? Or

optional?

Do you use random

seeds or parameter

vectors?

Is it stochastic?

Or deterministic?

Generate and test?Constructive?


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we can do it, so can you!


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http://trackgen.pierlucalanzi.net


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http://www.youtube.com/watch?v=uIUYWzdMXog


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http://www.michelepirovano.com/portfolio_swordgenerator.php


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http://www.polimigamecollective.org

http://www.facebook.com/polimigamecollective

http://www.youtube.com/PierLucaLanzi