Codemotion Milan - November 21 2015

Pier Luca Lanzi e Michele Pirovano – Codemotion Milan November 2015
Procedural Content Generation with Unity

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

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.

Pier Luca Lanzi e Michele Pirovano – Codemotion Milan November 2015http://en.wikipedia.org/wiki/Rogue_(video_game)#mediaviewer/File:Rogue_Screen_Shot_CAR.PNG

BBC Micro – 2 MHz MOS Technology 6502/6512
16-128 kB RAM 32-128 kB ROM

Pier Luca Lanzi e Michele Pirovano – Codemotion Milan November 2015https://www.youtube.com/watch?v=ISR4ebdGlOk

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
geometry
textures
animations
dungeons

Procedural Geometry
(Quads)

/// 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;
mesh.normals = normals;
/// create the UV for the full texture
Vector2[] uv = new Vector2[4];
uv[0] = new Vector2(0.0f, 0.0f);
mesh.uv = uv;
/// create the UV for half texture
Vector2[] uv = new Vector2[4];
mesh.uv = uv;

Procedural Geometry
(Polygons)

/// specify vertices
Vector3[] vertices = new Vector3[_no_sides];
float d = 2*Mathf.PI/no_sides;
for(int s=0; s<_no_sides; s++) {
vertices[s] = new Vector3(Mathf.Cos (-s*d), 0f,
Mathf.Sin (-s*d)) * _ray;
}
/// compute triangles no_sides-2 triangles, 3 indices each
int[] indices = new int[(_no_sides-2)*3];
for(int t=0; t<_no_sides-2; t++) {
indices[t*3] = t;
indices[t*3+1] = t+1;
indices[t*3+2] = vertices.Length-1;
}
/// ...

Procedural Geometry
(Surfaces)

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);
}
}

Procedural Geometry
(Cubes, Cylinders, Flowers)

Procedural Generation of Textures

structured noise

// Create the new texture
texture = new Texture2D(width, height, TextureFormat.RGBA32,
false);
// Assign it to the material
GetComponent<MeshRenderer>().material.mainTexture = texture;
// Generate the pixels
for (int y = 0; y < height; y++){
for (int x = 0; x < width; x++){
R = …
G = …
B = …
A = …
texture.SetPixel(x, y,
new Color (R, G, B, A));
}
}
// Apply the texture
texture.Apply();

// Noise pattern
noiseR =
SimplexNoise.noiseOctaves(nOctaves,xx*betaWR,yy,seed,frequenc
y);
// Alpha blending
valueR = (1-alphaR)+alphaR*noiseR;
// Sine pattern
valueR *= Mathf.Sin(noiseR*(sineX*x+sineY*y)*sineFrequency);

Procedural Animations

Procedural Animation

Animation in Unity
Skinned mesh renderer
Transforms = Bones

// Get all children transforms
var bones = gameObject.GetComponentsInChildren<Transform>();
// Rotate them using a sine wave
foreach(var bone in bones)
{
// Create a sine wave
float angle = Mathf.Sin(t + phase)*amplitude;
// Assign rotation
Vector3 tmpRot = bone.localEulerAngles;
tmpRot.z = angle;
bone.localEulerAngles = tmpRot;
}

Dungeon Generation

The Grid Map

// Mark the starting location
CellLocation currentLocation = starting_location;
map.MarkAsVisited(currentLocation);
// Pick a starting direction
Direction previousDirection = Direction.North;
// Repeat until all cells have been visited
while (!map.AllCellsVisited)
{
// Choose a direction
DirectionPicker directionPicker =
new DirectionPicker(map, currentLocation, directionChangeModifier,
previousDirection);
Direction direction = directionPicker.GetNextDirection(map, currentLocation);
// Check if we can go in that direction
if (direction != Direction.None)
{
// Create a corridor to the next cell and flag this cell as visited
previousLocations.Add(currentLocation);
previousDirection = direction;
currentLocation = map.CreateCorridor(currentLocation, direction);
map.FlagCellAsVisited(currentLocation);
} else {
// Backtrack
currentLocation = previousLocations[previousLocations.Count - 1];
previousLocations.RemoveAt(previousLocations.Count - 1);
}
Recursive Backtracking algorithm

Virtual Map -> Physical Map
// Choose a prefab based on the cell type
GameObject prefab = behaviour.GetPrefab(cell_type);
// Instantiate the prefab at the given position
GameObject go = (GameObject)GameObject.Instantiate(prefab, new
Vector3(l.x*behaviour.tileSize,l.storey*(behaviour.wallHeight
+behaviour.storeySeparationHeight),l.y*behaviour.tileSize),
Quaternion.identity);
go.name = cell_type.ToString();

we can do it, so can you!

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

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

http://www.polimigamecollective.org
http://www.facebook.com/polimigamecollective
http://www.youtube.com/PierLucaLanzi

47

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.
48

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?

Codemotion Milan - November 21 2015

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Codemotion Milan - November 21 2015