Control Time of Day on Ultra Dynamic Sky — setting/animating time, day/night cycles, the runtime functions (Set Time with Time Code, Set Time of Day with String, Transition Time of Day), the getter functions (Get Time of Day, Get Time Code, Get Date Time, Is It Daytime), and the event dispatchers (Sunrise, Sunset, Midnight, Hourly, Current Hour Changed, Every Minute, Custom Time). Use any time the user asks about time-of-day cycles, day/night transitions, animating time, triggering events at sunrise/sunset/midnight, displaying a clock, setting time programmatically, time speed / Day Length / Night Length, or syncing game events to the in-game time — even if they don't mention UDS in a project that already uses it.
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Control Time of Day on Ultra Dynamic Sky — setting/animating time, day/night cycles, the runtime functions (Set Time with Time Code, Set Time of Day with String, Transition Time of Day), the getter functions (Get Time of Day, Get Time Code, Get Date Time, Is It Daytime), and the event dispatchers (Sunrise, Sunset, Midnight, Hourly, Current Hour Changed, Every Minute, Custom Time). Use any time the user asks about time-of-day cycles, day/night transitions, animating time, triggering events at sunrise/sunset/midnight, displaying a clock, setting time programmatically, time speed / Day Length / Night Length, or syncing game events to the in-game time — even if they don't mention UDS in a project that already uses it.
UDS has a single canonical time variable, three categories of runtime control (set / animate / transition), four getter functions, and a complete event-dispatcher system for game logic that needs to react to time. For real-world astronomical positioning (lat/long/date), see uds-simulation.
Concern
Mechanism
Set the time
Time of Day variable (0–2400 float) or Time of Day String ("3PM", "15:45")
Day/night cycle
Animate Time of Day category: Day Length + Night Length (minutes)
One-off runtime change
Set Time with Time Code, Set Date and Time, Set Time of Day With String
Smooth transition over time
Transition Time of Day(targetValue, duration)
Read the time
Get Time of Day, Get Time Code, Get Date Time, Is It Daytime?
React at specific times
Event dispatchers: Sunrise/Sunset/Midnight/Hourly/Custom Time
Display the time
Built-in clock widgets in the widget designer palette
When to use this skill
Setting up a day/night cycle.
Triggering game events at sunrise, sunset, midnight, hourly, or arbitrary custom times.
Setting time programmatically from gameplay code (instantly or as a transition).
Reading the current time in HH/MM/SS form, or just checking "is it day".
Putting a clock on screen.
Syncing game time across multiplayer.
Setting the time
Time of Day is a float on UDS, 0–2400, in the Basic Controls category. You can also type a string like "3PM" or "15:45" into Time of Day String. Setting Time of Day directly at runtime instantly changes the time.
Animating time (day/night cycle)
In the Animate Time of Day category, enable Animate Time of Day. Then:
Setting
Unit
Meaning
Day Length
minutes of real time
Between sunrise and sunset
Night Length
minutes of real time
Between sunset and sunrise
When Simulate Real Sun is enabled (see uds-simulation), Day Length / Night Length are ignored — speed comes from Simulation Speed in the Simulation category (1 = roughly real-time).
Runtime control functions
Get a UDS reference with the shared Get Ultra Dynamic Sky function. Then call:
Function
What it does
Set Time with Time Code(TimeCode)
Set time from an hours/minutes/seconds Time Code struct
Set Date and Time(DateTime)
Set time using a Date Time struct (incl. simulation date)
Set Time of Day With String(string)
Parse 12:34 PM, 18:30, 5AM, etc. See function description for full list.
Transition Time of Day(target, duration)
Animate to target over duration seconds
Direct UDS.TimeOfDay = X also works for instant changes.
Sampling the current time
Function
Output
Get Time of Day
Float 0–2400
Get Time Code
Time Code struct (h/m/s)
Get Date Time
Date Time struct (h/m/s + simulation date)
Is It Daytime?
Boolean — true when the sun is up
Is It Daytime? is the right call when you only need day-vs-night, not the exact time.
Display widgets
Two clock widgets in the widget designer palette under Ultra Dynamic Sky Widgets. Drop into a UMG widget for a quick on-screen clock.
Event dispatchers
Bind events from your blueprints. Pattern:
UDS = GetUltraDynamicSky()
UDS.OnSunrise.AddDynamic(this, &MyActor::OnSunrise)
// Or in Blueprint: Bind to Sunrise → Custom Event
Dispatcher
When it fires
Output
Sunrise
Minute the sun crosses horizon going up
—
Sunset
Minute the sun crosses horizon going down
—
Midnight
Time of Day passes 0/2400
—
Hourly
Each hour. Fires for every hour skipped over by an instant time change.
Current hour (int)
Current Hour Changed
Like Hourly but fires once for the new current hour after an instant skip
Current hour (int)
Every Minute
Each minute
Current minute (int 0–59)
Custom Time
Time of Day crosses any value in the Custom Time Dispatchers float array
Array index that triggered (int)
Offsetting Sunrise / Sunset
Sunrise Event Offset and Sunset Event Offset in Animate Time of Day shift the trigger minute relative to the actual horizon cross.
Event check frequency
Time Event Dispatcher Check Period (Animate Time of Day) — how often the dispatcher logic checks for triggers. Default: every second whenever Time of Day is actively changing.
Hourly vs Current Hour Changed
If a fast Transition Time of Day skips from 14:00 to 18:00:
Dispatcher
Times it fires
Best for
Hourly
4 times (15, 16, 17, 18)
"Tick the clock for each hour passed"
Current Hour Changed
1 time (18)
"React to the new current time"
Custom Time example
In Animate Time of Day, set Custom Time Dispatchers to [630, 1230, 2200]. Bind to Custom Time. The bound event fires:
Index
At Time of Day
0
06:30
1
12:30
2
22:00
Use the index in a Switch to branch per scheduled time.
Material functions for time
Search the material palette:
Function
What it does
Day to Night Float
Interpolates between two float inputs based on whether sun is up. Inputs offset horizon threshold and widen/sharpen the transition.
Day to Night Color
Same for colors.
Good for materials that switch (e.g. emissive on at night) without involving a blueprint. For light components that turn on at night (not just materials), use the Light Day/Night Toggle component — see uds-lighting-and-shadows.
Sequencer
To keyframe Time of Day in Sequencer:
Disable Animate Time of Day on UDS (otherwise it overrides your keys).
Keyframe Time of Day directly. Going past 2400 is fine — UDS rolls into the next day.
Many UDS variables are exposed for cinematics, but not all are re-applied dynamically every frame. If a keyframed value doesn't update at runtime, mark it Expose to Cinematics in the UDS blueprint and call the matching Static Properties - <Category> function each frame. (Weather state has its own Sequencer notes — see udw-setup-and-state.)
Multiplayer replication
Time of Day and Date are replicated.
Variable
Replication behavior
Replicated Time of Day
Updated periodically; on change, clients sync Time of Day to it
Day Length, Night Length, Time Speed, Simulation Speed
Replicated themselves
Clients tick time locally between resyncs the same way the server does. Brief desync between resyncs is normal; the periodic Replicated Time of Day update realigns them.
Gotchas
Time of Day won't change at runtime — the sun is static or stationary mobility. Time-of-day cannot change at runtime with non-movable sun. See uds-lighting-and-shadows.
Keyframes in Sequencer have no effect — Animate Time of Day is still on and overriding. Disable it.
Sunrise/Sunset firing at the wrong time — Simulate Real Sun is on, which uses real horizon crossing rather than Dusk Time / Dawn Time. (See uds-simulation.) Or there's a Sunrise/Sunset Event Offset configured.
Hourly firing many times after Transition Time of Day — that's Hourly's intended behavior (every hour passed). Use Current Hour Changed for "once for the new hour".
Custom Time never fires — Custom Time Dispatchers array is empty. Add values.
Animation speed feels wrong despite Day Length / Night Length — Simulate Real Sun is enabled and overriding to use Simulation Speed instead.
