Look Presets
Modifier slots, composition precedence, effects, and reusable look authoring in Agentic Atmos
Look Presets
UAtmosLookPreset is a reusable atmosphere look for Agentic Atmos on Unreal Engine 5.8. A day-cycle slot selects the preset; the preset contains the actual lighting, air, weather-baseline, and grade settings.
An empty modifier slot means this preset asserts nothing for that category. It does not force that category off in the final scene: a lower layer may still supply it. It never inherits from the preceding timeline segment.
Modifier slots
Each slot is an instanced subobject saved inside its preset. Select a stock modifier or a compatible subclass, then edit its fields inline.
| Preset slot | Modifier class | Main authored fields / purpose |
|---|---|---|
Sun | UAtmosSunModifier | Sun: directional light intensity, colour, disc, shafts, and shadows. |
Moon | UAtmosMoonModifier | Moon, MoonSize, bOverrideMoonPhase, MoonPhase01: moon lighting, size, and optional phase pin. |
SkyLight | UAtmosSkyLightModifier | SkyLight: ambient captured sky lighting. |
SkyAtmosphere | UAtmosSkyAtmosphereModifier | SkyAtmosphere: Rayleigh, Mie, ozone, and aerial perspective. |
Fog | UAtmosFogModifier | Fog: exponential height fog and its volumetric medium. |
Clouds | UAtmosCloudsModifier | Recipe, Clouds, CloudCollection, RendererTag: cloud formation, typed settings, raw collection overrides, and renderer selection. |
SkyDome | UAtmosSkyDomeModifier | Dome, Shells: dome controls and an ordered set of sky-shell packs, including stars and overlays. |
PostProcess | UAtmosPostProcessModifier | PostProcessSettings: Unreal's native exposure and colour-grade settings. |
LocalFog | UAtmosLocalFogModifier | LocalFog: local fog-volume mood. |
GroundFog | UAtmosGroundFogModifier | GroundFog, RendererTag: terrain-relative ground mist. An empty renderer tag fails closed. |
Wind | UAtmosWindModifier | Wind: ambient wind baseline. |
Weather | UAtmosWeatherModifier | Weather: weather baseline asserted by this look. |
All derive from UAtmosLookModifierBase, which also exposes ChannelAdjustments and ChannelColors for the shared value-adjustment surface. The sun and moon share UAtmosLightBodyModifierBase.
The moon phase pin uses 0 for new, 0.25 for first quarter, 0.5 for full, 0.75 for last quarter, and 1 for new again. Moon path is a cycle/calendar choice, not a modifier-slot setting.
Precedence ladder
For each asserted category, higher layers take precedence over lower ones:
| Priority | Layer | What supplies it |
|---|---|---|
| Highest | WeatherLook | Weather look applied over the composed day, weighted by weather severity. |
| 4 | Slot | Retained inline overrides on a timeline slot. A compatibility layer, not the normal authoring surface. |
| 3 | Preset | The slot's LookPreset. |
| 2 | BaseLook | The cycle's common baseline preset. |
| Lowest | ActorDefaults | The applying sky actor's fallback settings. |
A category that a layer does not assert falls through. The outgoing and incoming timeline looks are composed separately and then blended through the transition. Weather is layered over that day result.
A preset can appear to have no effect when a retained inline slot override asserts the same group above it. Use the segment promotion tools to move that authored state into a preset and clear the hidden copy. Do not repeatedly copy a preset back into its slot as a normal editing workflow.
Wind has its own assertion handling rather than a matching category gate in the group ladder; do not infer its behavior from an unrelated bEnable* field. An empty ground-fog modifier slot inherits; to explicitly clear ground fog, disable it within an assigned ground-fog modifier.
Post-process blending
The sky actor owns two post-process components so the engine can blend the outgoing and incoming grades. A weather look that asserts post-process replaces both sides once its severity reaches 0.5; weather post-process is not a third continuously weighted component.
Effects
Effects is an ordered array of instanced UAtmosEffectModifier objects. Category modifiers state the base look; effects adjust the composed result per refresh before component writes. Effects run from top to bottom. A later override can replace an earlier result, and multiplication compounds in authored order.
Use AT.Debug.HUD 2 to inspect the contributor ledger. The console reference lists the HUD levels.
Identity and programmatic access
| Field or method | Purpose |
|---|---|
Thumbnail | Editor-only image shown on the preset's Content Browser tile. |
ReferenceImagePath | Reference-image provenance; not a render input. |
AuthoredAtSunElevationDeg | Authored sun-elevation provenance; not a celestial driver. |
BuildLook() | Compose the preset into the runtime FLightingSegment payload. |
AdoptAssertedGroups(Layer, bClearUnasserted) | Fold asserted groups into modifier slots; optionally clear slots for unasserted groups. |
The serialized Look field is load-only compatibility data, not the editing surface. Author through modifier slots or AdoptAssertedGroups rather than assigning that field. Shared preset assets are intentionally reusable: editing one changes every cycle slot that references it.
See day-cycle fields, editor toolsets, or support.