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Skillsue-udw-setup-and-state

ue-udw-setup-and-state

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Updated 11-06 16:17

About this skill

UDW setup and weather state

The foundation of Ultra Dynamic Weather: getting the actor in place, the weather state model, presets, runtime transitions, the manual state for sequencer/per-value control, sampling weather from gameplay code, and event dispatchers.

Concept Mechanism
Weather is a preset asset (high-level) Weather variable in Basic Controls; or Change Weather(preset, duration)
Weather is a custom blend (low-level) Manual Weather State category, with per-value override toggles
What weather looks like right now Sample via Get Cloud Coverage, Get Display Name for Current Weather, etc.
React to weather changing UDW event dispatchers (Started Raining, State Change - <Value>)
Per-actor exposure tracking Actor Weather Status component
Multiplayer UDW replicates state-source asset references, not raw state

When to use this skill

  • Adding UDW to a level for the first time.
  • Choosing or applying a weather preset (Rain, Blizzard, Thunderstorm, etc.).
  • Triggering a weather change from gameplay code.
  • Overriding individual weather values without writing a new preset.
  • Reading current weather from a blueprint (state values or display name).
  • Wiring game events to weather transitions (sunrise of a storm, end of snowfall).
  • Tracking how exposed an individual actor (player pawn) is to weather.

Adding UDW to a level

UDW requires UDS — make sure there's an Ultra Dynamic Sky actor in the level first (see ue-uds-setup-and-modes).

Drag an Ultra Dynamic Weather actor from the Blueprints folder into the scene. It detects UDS automatically and hooks everything up.

By default, UDW starts with a manual weather state matching the Cloud Coverage and Fog already set on UDS. The Weather variable in Basic Controls lets you apply different weather presets immediately.

Basic Controls

Setting Purpose
Weather Select a weather preset (Rain, Partly Cloudy, Blizzard, Thunderstorm, etc.). Clearing → falls back to Manual Weather State.
Wind Direction Degrees. Drives weather particle movement and cloud movement on UDS.

Advanced dropdown holds additional knobs (Control Point Location Source — see ue-udw-spatial-weather; configuration override — see ue-uds-modifiers-configs-state).

Weather state

The set of values that defines "what weather is" right now.

State value Type Notes
Cloud Coverage float If UDS-only project, set on UDS; if UDW present, UDW owns it
Fog float Same
Wind Intensity float Drives wind effects (gusts, particles, physics force)
Rain float Drives rain particles, drips, screen droplets
Snow float Drives snow particles, screen frost, breath
Dust float Drives dust particles, fog dust color contribution
Thunder/Lightning float Drives lightning flash interval, obscured lightning

Plus material state — drives material effect functions:

Material state value Drives
Material Snow Coverage Snow coverage in DLWE / Surface Weather Effects
Material Wetness Wetness / puddles in DLWE / Surface Weather Effects
Material Dust Coverage Dust coverage in Surface Weather Effects

The visible material state at runtime isn't always directly the weather state values — see ue-udw-material-and-screen-effects for the Simulate Changing Material State Over Time option.

What determines weather state

The active state can come from any combination of these sources (specificity layers from global → local):

Source Scope
Weather preset in Basic Controls Global default
Change Weather(preset, duration) function Global, transitions
Random Weather Variation Global, periodic (see ue-udw-random-seasons-temperature)
Manual Weather State Global, used when no preset selected. Per-value override toggles.
Weather Override Volumes Local to a spline region (see ue-udw-spatial-weather)
Radial Storms Local circular region with visible distant storm effects (see ue-udw-spatial-weather)

Weather Settings Presets

Preconfigured weather states as data assets. Used by Weather, Change Weather, Random Weather Variation, Weather Override Volumes, and Radial Storms.

Blueprints/Weather_Effects/Weather_Presets/
   ├── Rain
   ├── Partly_Cloudy
   ├── Blizzard
   ├── Thunderstorm
   └── ...

Creating custom presets

Easiest: duplicate one of the included assets in Blueprints/Weather_Effects/Weather_Presets/ and edit its settings. Your new asset works everywhere the included ones do.

Custom Weather Behavior (per-preset Blueprint logic)

The UDS_Weather_Settings data asset class has a Custom Weather Behavior function meant for override. To add custom logic to a preset:

1. Create a child of UDS_Weather_Settings
2. Override Custom Weather Behavior
   (parent applies the Sky Modifier on the preset — call Super if using one)
3. Make data assets using the child class

The function has an Alpha input (0–1): how much this preset is currently affecting local weather state. Called at runtime as weather state changes in any way involving this preset.

Change Weather

To trigger a weather change at runtime (instantly or over a duration):

UDW.ChangeWeather(targetPreset, transitionLengthSeconds)

The new global state stays applied indefinitely, until another change is called for.

Call Effect
ChangeWeather(Blizzard, 10) Transitions to Blizzard over 10 seconds
ChangeWeather(null, 5) Transitions to Manual Weather State over 5 seconds
ChangeToRandomWeatherVariation() Returns to random variation after a manual override

Manual Weather State

For individual weather values without a preset. Category: Manual Weather State.

1. Clear the Weather setting in Basic Controls (no preset selected)
2. Edit values in the Manual Weather State category — they become active

Per-value overrides

Override one value while keeping the rest from a preset. Example: Thunderstorm preset is active, but set Manual Rain Override = true and pick a custom Manual Rain value — rain comes from your manual value, everything else from Thunderstorm.

Each weather state value has an override toggle and a manual value pair in this category.

Sampling weather state (runtime)

Function Output
Get Cloud Coverage float (blueprint function library)
Get Wind Intensity float
(and one Get function per state value) Each weather state value
Get Local Weather State (off a UDW reference, or via the library) The current Weather Settings object used by effects/sky
Get Display Name for Current Weather Text label like "Light Rain", "Blizzard"

Get Display Name for Current Weather is what to call when you want to surface a weather label in UI without parsing individual values. For temperature, see ue-udw-random-seasons-temperature.

Weather event dispatchers

Bind events from your blueprints. Pattern:

UDW = GetUltraDynamicWeather()
UDW.OnStartedRaining.AddDynamic(this, &MyActor::OnRainStart)
// Or in Blueprint: Bind to Started Raining → Custom Event
Dispatcher Fires when
Started Raining / Finished Raining Rain crosses a threshold
Started Snowing / Finished Snowing Snow crosses a threshold
Dust/Sand Forming / Dust/Sand Clearing Dust crosses a threshold
Getting Cloudy / Clouds Clearing Cloud coverage crosses a threshold
Getting Foggy / Fog Clearing Fog crosses a threshold
Weather Display Name Changed Output of Get Display Name for Current Weather changes — best generic "weather changed" hook
State Change - <Value> A specific weather state value changes. Bind to State Change - Rain for any rain change.

The threshold for the started/finished dispatchers is in the Event Dispatchers category on UDW.

Actor Weather Status component

Per-actor weather tracking. Intended for important actors (e.g. the player pawn) that need to constantly monitor their own status.

At runtime, the component periodically traces to test exposure and tracks how the actor's temperature is affected. All values are in the component's Status category.

Features:

Feature Detail
Per-component event dispatchers Fires when this actor gets exposed to rain or snow, or temperature passes thresholds for hot/cold. Different from UDW's global dispatchers.
Material Effects array Add dynamic material instances to have UDW-style parameters set using the actor's local status: Wet, Raining, Snowy, Dusty, Wind Intensity (all 0–1). UDW material functions have a Use Local Parameters input that pairs with this.

One-off exposure query without a component

UDW.TestActorForWeatherExposure(actor) → rain, wind, snow, dust (each 0-1)
// Floats combine weather intensity with actor exposure.
// 1.0 = fully exposed to that effect at max intensity.

Sequencer

To animate the weather state in Sequencer, use Manual Weather State and keyframe its variables.

For material effects (Material Wetness/Snow Coverage/Dust Coverage), to make keyframes look identical at runtime to in-sequence: in the Material Effects category, disable Simulate Changing Material State Over Time. Otherwise runtime gradually transitions between values instead of matching keyframes precisely.

Multiplayer replication

UDW replicates weather state for multiplayer:

What replicates How
Global Weather State source assets Preset assets used by the transition system, random variation, Weather Override Volumes, Radial Storms. Not raw state values.
Clients construct Local Weather State themselves Each player can experience their own local weather (e.g. different WOVs they're inside); the underlying state of the volumes/storms is shared.

Result: updates only need to go over the wire when a state-source change starts. Between updates, clients track state the same way the server does.

Gotchas

  • Cloud Coverage / Fog on UDS ignored — UDW is in the scene; it owns those values. Set on UDW's weather state instead.
  • Change Weather doesn't appear to transition — transitionLengthSeconds was 0 (instant change). Pass a duration for a smooth transition.
  • Setting Weather to a preset has no effect at runtime — preset assignment is editor-time. Use ChangeWeather(preset, duration) from blueprint to switch at runtime.
  • Material wetness/snow doesn't match keyframes in Sequencer — Simulate Changing Material State Over Time is on. Disable it for direct keyframe playback.
  • Manual Rain value ignored — Manual Rain Override is off. Override toggles must be enabled for per-value manual values to apply.
  • Weather display name shows "Manual Weather" — no preset is selected; UDW falls back to Manual Weather State. Set the Weather variable or call ChangeWeather(preset, ...).
  • Per-actor wetness in materials not working — the material's Use Local Parameters pin isn't set, or the dynamic material instance wasn't added to the Actor Weather Status component's Material Effects array.
  • Started Raining / Started Snowing fires at the wrong threshold — adjust thresholds in the Event Dispatchers category on UDW.
  • Random Weather Variation overriding ChangeWeather — call ChangeToRandomWeatherVariation() to return control, or disable Random Weather Variation in its category.

References & source material

Docs (Ultra Dynamic Weather 9.5):

Plugin asset paths:

  • Blueprints/ — Ultra Dynamic Weather actor (drag from here)
  • Blueprints/Weather_Effects/Weather_Presets/ — included preset data assets (UDS_Weather_Settings)
  • Blueprints/Weather_Effects/ — Actor Weather Status component

Related skills: ue-uds-setup-and-modes (UDS must exist first), ue-udw-random-seasons-temperature, ue-udw-spatial-weather, ue-udw-particles-lightning-wind-sounds, ue-udw-material-and-screen-effects, ue-uds-modifiers-configs-state (Apply Weather Configuration, save/load state).