A client-side Fabric mod that draws a tall, translucent red wall on the chunk borders at the edge of your simulation-distance region, so you can see at a glance which chunks around you are actually being ticked.
Simulation distance is invisible in vanilla, and it is not the same as render distance — chunks you can see are frequently not chunks that are running. That gap is why a mob farm stops producing when you wander a little too far, why a crop field stops growing, and why a redstone contraption quietly stalls. SimDistance draws the line so you can stay on the right side of it.
- A hollow box snapped to chunk borders,
radiuschunks out from the chunk you are standing in. It re-centers in 16-block steps as you cross chunk lines. radiusdefaults to the live simulation distance reported by the server (ClientWorld.getSimulationDistance()), which is synced in singleplayer too. You can override it with a fixed chunk radius.- The wall spans the full world height by default, or a fixed band around you.
- Optionally, a per-chunk floor grid inside the region, at your feet level.
- G — toggle the border on/off (rebindable in Options → Controls → SimDistance). The confirmation goes to your chat log, locally — see below.
- ModMenu → SimDistance → Settings — everything in the table below. Requires Cloth Config.
| Setting | Default | Description |
|---|---|---|
| Enabled | on | Master on/off. Also bound to the hotkey. |
| Use Server Simulation Distance | on | Track the live value the server reports. Turn off to use a fixed radius. |
| Manual Chunk Radius | 8 |
Used when the above is off, or as a fallback if the server reports nothing. |
| Wall Colour | red | Red/green/blue channel sliders. |
| Wall Opacity | 22% |
How solid the translucent wall is. 0 leaves only the edge lines. |
| Full World Height | on | Span bedrock to build limit. Off uses a fixed band around you. |
| Vertical Radius | 48 |
Half-height of that band, when full height is off. |
| Draw Edge Lines | on | Crisp outline along the top/bottom edges and vertical corners. |
| Show Chunk Grid | off | Per-chunk grid on the floor within the region. |
| Dependency | Required | Notes |
|---|---|---|
| Fabric Loader ≥ 0.15 | Yes | |
| Fabric API | Yes | |
| Java 25 | Yes | |
| ModMenu | Recommended | Needed to reach the config screen |
| Cloth Config | Recommended | Needed for the config screen UI |
TrarnCore is bundled inside the jar — do not install it separately.
The toggle confirmation goes to your chat log via ChatHud.addMessage, which appends straight to
the client's own message list. No packet is involved, so nothing reaches the server or other
players — it is not the same thing as sending a chat message. (ChatHud contains no networking
code at all; sending chat goes through ClientPlayNetworkHandler.sendChatMessage, which this mod
never calls.)
Chat rather than the action bar on purpose: the action bar is a single slot that servers, scoreboards and other mods all write to, so anything put there tends to be overwritten a tick later — or to overwrite something you wanted to read. Chat is a log, so several sources coexist.
On a fresh clone, build TrarnCore once first — Loom reads the library jar at configuration time, so it must exist before this mod can even be configured:
(cd ../TrarnCore && ./gradlew build). After that, no ordering is needed.
./gradlew buildThe jar lands in build/libs/, and is also copied to ../ModBuilds/ alongside the
other mods' output for easy installing. Requires JDK 25.
Minecraft/Loader/Fabric versions come from ../versions.properties,
shared with the sibling mods, so a version bump is one file for all of them.
TrarnCore is built from source automatically via a Gradle composite build — there is
no publish step.
- Client-side only. Nothing is installed or changed server-side; the mod only draws what the server already tells your client.
- The border reflects simulation distance, not render distance. Where the two differ is exactly what this mod exists to show you.
ClaimViz · EasyPortalLinker · ContainerUtil · RSwitch · TrustUI · AutoRelog — same Minecraft/Fabric target, shared TrarnCore plumbing.