U PCG

Posted on | In
RAW

Related notes: Procedural, Level Design

PCG

Data driven Scriptable procedural content framework. Spawn meshes on points. We can cache and reuse calculations. Dependences: you can remove points from bigger assembly. You can spawn on level or on runtime. Smaller detail (without collision which is expensive to spawn) should be spawned Runtime to not overload RAM.

  • PCG Graph - with instances
  • PCG BP
  • PCG Actor component

Useful tips:

  • Subgraphs -use as fn Use graph inside other graph
  • Tags
    • PCG > Utilities > Actor Tagger > EUW_Actor_Tagger
  • Data Assets » struct (with mesh information )

    Shortcuts

    A - Attributes D - Debug E - Enable

Attribute & Property

  • Static Attributes:
    • $Density -  A density of 0 is black, and a density of 1 is white.
    • $Scale, $Position.z
    • @Last -  dynamic attribute that was manipulated by the previous node.
  • Dynamic Attributes:
    •  Runtime, and stored as part of the Metadata of the graph data
  • Graph Parameters
    •  Customizable graphs

Extents

  • Bounds Modifier - Change position (similar to extent)
  • Extents Modifier - Change scale of boxes (Bounds.Max-Bounds.Min)/2

Generation modes

Offline

  • Default

    On Demand

  • BP nodes:
    • Generate BP node - with PCG target will regenerate (force to generate even if not been before)
    • Set Seed - Set Seed of given PCG actor

      Runtime

  • PCG component details:
    • Generation tirgger Runtime
    • Overrid GEneration Radii > Shedule policy class
      • [ ]
  • Actor: PCG World Actor:
    • [v] Treat Editor Viewport as a runtime generation source

Partition

For large volumes - When enabled is moving generated meshes to partition actor. You want to set it up with: Runtime gen and HLOD Actors

How to enable:

  • PCG:
    • Class settings: Use hierarchical gen
    • HiGen Default Grid Size Can be UB - unbounded (3200)
  • PCG component details:
    • Is Partitioned
  • Grid Size
    • Set up partition grid size in PCG world actor

Cavoites

  • If leftovers Tools > PCG Framework> Delete all uinbused PCG partition actors
  • Self is now partition actor sow will copy created points to center of all partitions (Original should fix) and then maybe need to resolve intersections

Hierarchical Generation

Allow for referencing points on grid

  • PCG - Graph settings:
    • Grid Size node - Gates to force downstream graph in given size.
      • Can compute on higher and used on lower grid size
      • Only smaller (64) grid sizes can use data from bigger (128) high gen default grid size (Bigger Grid size for big / smaller values for grass)
  • PCG node - Grid Size - [ ] off : Ignore self hits - [ ] collision - PCG Component data - Get data from offline (select by tag)
    • Projection to : World Ray Hit Query
    • Gather node - if you want wait for other nodes

Communicate

Re-use offline computed data in runtime.

Output

  • Output node. - everything will be serialized - on pcg component you can find Generated Graph Outputs

Input

  • PCG Component data
    • use with tag and overlap self

I/O

  • Save PCG Data Asset - Export
  • Level Instance to PCG:
    • Asseet Action > Create PCG Asset From level. Then drag to PCG Graph (Load PCG Data Asset)
    • Add tags to StaticMeshes in level instance (Then RMB and: update assets) > Those attributes can be read in PCG and filter by AttributeFilter
#### Offline to Runtime
offline 
- Output point with labels
- mesh spawn can modify bounds so sometimes (trees) need to disable modify bounds on static mesh spawner

Dictionary

  • Get Actor Data Get Componen by class
  • Merge Attributes -
  • Save PCG Asset - Save data to asset BP
    • spline
    • pcg with grammar
    • https://youtu.be/j3ke6MmcaeY?t=359

PCG Nodes

  • Attribute operation - duplicate attribute with different name
  • ‘Math’ -

    Create Points

    You can get points out from spatial data - points, volume, mesh, landscape

  • Create points Grid - Create grid of points in 0,0,0.
    • Grid Extent - wielkość siatki
    • Cell size - wielkość
  • Get Landscape Data > Surface Sampler - sample landscape points Landscape is surface >surface is spatial data
  • GetSplineData > Spline Sampler- sample spline
  • Mesh Sampler
  • Mesh to points - slower than sampler

    Project Points

  • Projection - can project data

    Filters Density

White and Black gradient on preview boxes.

  • Density Filter - min max on Density (point filter specific version)
  • Density remap - remap
  • Density Noise -

    Filters

    filter data based on criteria or per-point.

  • Distance - distance
    • ?
  • Point Filter «< target attribute (simpler version is density filter )
    • i.e.: by landscape layer

  • Intersection - Boolean np duize punkty od malych mozna odjąć !!!!!!!!!!!!!!!!!!!!

  • Attribure Filter - Surface sampler , sample material »> AF:

    Transform points

  • Copy Points - Houdini copy to points
  • Transform Points - transform
    • to rot up: turn on: absolute rotation
  • Multiplay -
    • Scale : $Scale , $Density , $Scale
  • Difference - mozna usunąć nachodzące punkty ale Bounds muszą być ok ! (jak nie to zmien by bounds modifire)! PORÓWNYWANIE CHMURY PUNKTÓW !!!!!!!!!!!!!
  • Select - can select
  • Landscape Project - but reset rotations

    Spawner

    Green nodes

  • Static Mesh Spawner
    • This node is creating ISM components with resulting geometry. You fire
    • can disable just this node for debug.

      Get Data

  • Get Actor Data
    • Actor filter: Patent / Root / All World actors (can be slow) /
    • Mode: data from property can be used as attribute

      Tech

  • World Ray Hit Quarry -
    • can get reference from physical material
  • Get Actor Property
  • property to parameter data - PARAMETERS INPUT FROM BLUEPRINT
    • self - from actor belong ro pcg «

Blueprint / Control Flow / Debug / Spatial

Optimize

spawnuj rzec zy bez kolizji daleko

Sources

YT Adrien Logut YT Dengojaba

spawn instances Unreal Engine 5 Tutorial - Open World Optimization: Don’t use actors too much Natural scaling density - UnrealityBites Freetime Coder - basics

  1. overview
  2. path cut throuy other pcg by tag.
  3. project gdir spawn points
  4. subgraphs
  5. actor and attributes: BP > add PCG component powinno działac
    https://youtu.be/nq7aqU2F6mQ?list=PLA03OHAaHgYpo0enf8p-2oEpja3grLOKZ&t=348
  6. Sampling meshes > copy to points mesh source
  7. Custom Nodes
  8. jungle biom Michael Royalty - flowers and bends / loops - triki ale nudnny 1
  9. Custom data material in spawned elements https://youtu.be/5PM9dq0jWGc?list=PLzvhOHK7paz7EqFQ3SjX0WcJbHYKB-dkw&t=1122
  10. Position to middle of mesh https://youtu.be/MgXGXg8roUE?list=PLzvhOHK7paz7EqFQ3SjX0WcJbHYKB-dkw&t=99 2
  11. Water splines https://youtu.be/e7VtqD1L19U?list=PLzvhOHK7paz7EqFQ3SjX0WcJbHYKB-dkw
  12. PCG World Ray Hit Query https://youtu.be/XiBRJAtHIDk?list=PLA03OHAaHgYpo0enf8p-2oEpja3grLOKZ

UE5.3 PCG - Ep 5 - Parameters and runtime execution https://youtu.be/0NQAQPaJ8ko

srednie Deep Dive into the Electric Dreams Project

Guides

Find Actor

  • find actor by tag

    Spawn on Landscape

    1. Get Landscape Data
    2. Surface Sampler
    3. Projection

      Spawn on Spline

    4. GetSplineData
    • can from comonent if added to pcg vpoolume
    • can all world actors. - by tag / name / class
      1. Spline Sampler

        Spawn on Spline w BP

        to jest spawn i jakies dodatkowe bzdurne kopiowanie scien budynku YT

  1. Create
    • BP Actor
    • BP Actor of class: PCGBlueprintElement
    • CG Graph
  2. Add spline and pcg to BP as […]
  3. PCG: Get spline data > spline sampler - now BP should work out of the box
  4. in PCGBlueprintElement > Clas sdetails > Expose to library (of pcg nodes)

Spawn on Surface

`World Ray Hit Querry` > `Surface Sampler`  < !!!!  spawn on world 
 To spawno on other spawned 
 - ignore self hits 
 - eqxec order << DEPENDENCY (to 2 input of surface sampler)

BP regenerate on demand:

![[Pasted image 20250119071451.png]]