procedural content generation with unity

Pier Luca Lanzi e Michele Pirovano – Codemotion Milan November 2015

Procedural Content Generation with Unity


what’s the basic principle?


f(x) = sin(x)

float y = 0f; for (float x = 0f; x<6.28f; x+=.01f) { y = Mathf.Sin(x); }


What the ingredients?

domain knowledge

structured randomness

multi-layering

filters, limits & restrictions

specialized algorithms

artificial intelligence

gameplay integration


Outline

procedural geometry

colors & music


Procedural Geometry


/// specify vertices Vector3[] vertices = new Vector3[4]; vertices[0] = new Vector3(0.0f, 0.0f, 0.0f); vertices[1] = new Vector3(0.0f, 0.0f, m_Length); vertices[2] = new Vector3(m_Width, 0.0f, m_Length); vertices[3] = new Vector3(m_Width, 0.0f, 0.0f); /// specify 2 triangles int[] indices = new int[6]; /// triangle 1 indices[0] = 0; indices[1] = 1; indices[2] = 2;

/// triangle 2 indices[3] = 0; indices[4] = 2; indices[5] = 3; /// create the mesh Mesh mesh = new Mesh(); mesh.vertices = vertices; mesh.triangles = indices; mesh.RecalculateBounds();


/// create the normals Vector3[] normals = new Vector3[4]; normals[0] = Vector3.up; normals[1] = Vector3.up; normals[2] = Vector3.up; normals[3] = Vector3.up; mesh.normals = normals; /// create the UV for the full texture Vector2[] uv = new Vector2[4]; uv[0] = new Vector2(0.0f, 0.0f); uv[1] = new Vector2(0.0f, 1.0f); uv[2] = new Vector2(1.0f, 1.0f); uv[3] = new Vector2(1.0f, 0.0f); mesh.uv = uv; /// create the UV for half texture Vector2[] uv = new Vector2[4]; uv[0] = new Vector2(0.0f, 0.0f); uv[1] = new Vector2(0.0f, 1.0f); uv[2] = new Vector2(0.5f, 1.0f); uv[3] = new Vector2(0.5f, 0.0f); mesh.uv = uv;


public class MeshBuilder {

public List<Vector3> Vertices; public List<Vector3> Normals; public List<Vector2> UVs;

public void AddTriangle(int i0, int i1, int i2); public Mesh CreateMesh()

} MeshBuilder meshBuilder = new MeshBuilder(); //Set up the vertices and triangles: meshBuilder.Vertices.Add(new Vector3(0.0f, 0.0f, 0.0f)); meshBuilder.UVs.Add(new Vector2(0.0f, 0.0f)); meshBuilder.Normals.Add(Vector3.up); ... meshBuilder.AddTriangle(0, 1, 2); meshBuilder.AddTriangle(0, 2, 3); ...


MeshBuilder meshBuilder = new MeshBuilder(); for (int i = 0; i < m_SegmentCount; i++) { float z = m_Length * i; for (int j = 0; j < m_SegmentCount; j++) { float x = m_Width * j; Vector3 offset = new Vector3(x, Random.Range(0.0f, m_Height), z); BuildQuad(meshBuilder, offset); } }


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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.

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ESEMPIO CON LA CAVE? ESEMPIO DI DUNGEON?


ingredient #3

structured randomness

things look like they have been randomly

generated but it is not completely at random!


f(x) = sin(x)


they both look like “noise”

but one of them feels like it has structure…

it is structured randomness


ingredient #4

multi-layering

typically more layers of procedural

content generation are applied in sequence


• Warzone 2100

§ Heights & Cliffs

§ Roads

§ Textures

§ Player Bases

§ Local Features

•  Civilization 4

§ Fractal Heightfield

§ Plate Tectonics

§ Tile Types

§ Rivers and Lakes

§ Map Bonuses


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

iron, or each element of horses, and that completely solved the

problem.” – Soren Johnson


ingredient #6

specialized algorithms

placing special items, requires special tricks

this tricks must be encoded in the PCG


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.


ingredient #7

gameplay integration

Is it fun to play? Is the progression adequate?


is this all there is?


PCG

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?


we can do it, so can you!

Pier Luca Lanzi e Michele Pirovano – Codemotion Milan November 2015 http://trackgen.pierlucalanzi.net


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

Pier Luca Lanzi e Michele Pirovano – Codemotion Milan November 2015 http://www.michelepirovano.com/portfolio_swordgenerator.php


http://www.polimigamecollective.orghttp://www.facebook.com/polimigamecollective

http://www.youtube.com/PierLucaLanzi

procedural content generation with unity

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