Contents
Unreal Engine 5.8 · Focused reference
Debugging, validation, and profiling
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Graph-debug procedure
- Enable node Debug on the earliest suspicious stage.
- Inspect the Data View and Attributes List: count, bounds, density, transforms, seed, attributes.
- Move the debug point downstream one stage at a time.
- Disable spawners while validating data.
- Use graph/node profiling to identify CPU cost; use Unreal Insights for system-level cost.
- Cleanup and regenerate to eliminate stale output.
Runtime tools
pcg.RuntimeGeneration.EnableDebugOverlay 1: scheduler/runtime overview.pcg.GraphExecution.DebugDrawGeneratedCells 1: sources, generating cells, grid/coordinates.pcg.RuntimeGeneration.EnableDebugging: verbose scheduler logging.pcg.RuntimeGeneration.Refresh: cleanup and schedule regeneration.pcg.RuntimeGeneration.Enable: freeze/enable runtime generation.pcg.GPU.FuzzMemory: expose uninitialized GPU output assumptions.
Debug overlays are not generally available in Shipping and may differ by build configuration.
Validation matrix
- empty input and zero points;
- smallest and largest bounds;
- steep/vertical/overhanging surfaces;
- overlapping exclusion volumes and Data Layers;
- seed zero, repeated seed, and changed seed;
- missing asset/table row/soft reference;
- cleanup -> regenerate -> reload -> cook;
- source control clean checkout and commandlet generation;
- target platform scalability/feature-level switches;
- fast traversal/teleport and multiple runtime sources;
- maximum shipping density plus HLOD/nav/collision build where required.
Common failures
| Symptom | First check |
|---|---|
| Points exist but nothing spawns | mesh/actor selector attribute, bounds, node enabled, output path |
| Same random choice repeats | duplicated seeds; place Mutate Seed at intentional branch |
| Content leaks into roads/buildings | exclusion input/bounds and Difference mode/order |
| Graph regenerates constantly | tracked actor/component changes or circular dependencies |
| Runtime pop-in | generation radius, bounds modifier, scheduler budget, traversal speed |
| Cleanup leaves stale actors | generation ownership, partition actors, grid change cleanup sequence |
| GPU path slower | transfers, small data, compute-graph fragmentation, preparation cost |
| Packaged result differs | editor-only input/node, unsupported platform path, unbuilt persistent output |
Performance record
Record point count, spawned instance/Actor count, CPU node times, GPU execution/memory, generation latency percentile, cache memory, cleanup time, streaming overlap, and final render cost. PCG graph time alone does not include the lifetime cost of what it spawned.
Sources and version
Documentation target: Unreal Engine 5.8. Confirm behavior in your installed engine; no per-procedure test result is implied.
Read this system’s sources and verification notes →
Canonical reference and AI copy
unreal-pcg/references/debugging-validation.md