60 lines
2.6 KiB
Markdown
60 lines
2.6 KiB
Markdown
---
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id: time
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icon: play.speed
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group: gameplay
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title: Time
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order: 2
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---
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# Time
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Every world has its own clock with several domains:
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- **Real**: wall time between frames, cut to `maxFrameDelta` (0.1 s by default) so a stalled frame or a minimized window cannot produce a huge step.
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- **Game**: Real × Scale. It is 0 while paused. `time.Delta()` and `time.Elapsed()` read it.
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- **Fixed**: a constant step (`fixedHz`, 60 by default). Game time fills an accumulator; each full step runs FixedUpdate and physics. At most `maxFixedSteps` (4) steps run per frame; extra steps are dropped and counted in the profiler as *dropped ticks*.
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- **Editor**: the editor's own time. It never pauses with the game.
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Each world counts its frames and fixed steps. `time.Frame()` and `time.Tick()` return the same numbers that the profiler and the Event Monitor show.
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## Pause, step and scale
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- **Pause** stops Game and Fixed time. Rendering, overlays and the editor keep running.
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- **Step Frame** runs one Update and the fixed steps the accumulator holds for that frame, zero or one.
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- **Step Fixed** runs exactly one fixed step (FixedUpdate, physics, collision events) and no Update.
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- **Time Scale** from 0 to 8 changes how much game time passes per real second. The fixed step keeps its length, so physics behaves the same at 0.25 as at 1, only slower.
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Time spent paused never piles up: resuming after a long pause runs one ordinary frame.
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## Project settings
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The `engine` block of `project.aego` sets the limits. A missing field keeps the default.
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engine {
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fixedHz=60.0
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maxFrameDelta=0.1
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maxFixedSteps=4
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}
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## Systems
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A Go system chooses what it does while paused with `Pause` in its `SystemDesc`: `PauseNormal` (stops), `PauseAlways` (runs every frame) or `PauseWhenPaused` (runs only while paused). The pause mode applies to the fixed and update phases; input and rendering always run.
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## Scripts
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@pause("always")
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script PauseMenu {
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func Update(dt float) {
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if input.KeyPressed(input.KeyEscape) {
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time.SetPaused(!time.IsPaused())
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}
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}
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}
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- `@pause("normal")` (the default): Update stops while paused.
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- `@pause("always")`: Update runs every frame, paused or not, and `dt` is real time. Use it for menus and HUD.
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- `@pause("whenPaused")`: Update runs only while paused.
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FixedUpdate always follows fixed steps. `yield wait(s)` counts game seconds and stands still while paused; `yield waitUnscaled(s)` counts real seconds and keeps running while paused. `frames(n)` counts game frames, `fixed(n)` counts fixed steps.
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