World Preview (Unofficial Port)

World Preview is a mod for visualizing Minecraft world seeds before they are generated.

This is a community-maintained fork of the original World Preview by Caeruleus Draconis & Taiterio. The original project has not been updated since Minecraft 1.21. This fork upgrades the mod for Minecraft 1.21.11 and later, adding new features — all while preserving the original experience.

Installation

Download the latest World Preview JAR file for Minecraft 1.21.11 and later . For the Fabric Loader, you also need Fabric API. Save both jar files to the mods folder of your Minecraft instance.

Usage

World Preview adds a new Preview tab to the Singleplayer menu.

Upon opening that tab, a random seed is selected and a map of biomes is generated:

By default, the overworld dimension will be generated, structures will not be shown and no heightmap will be generated. This can be changed in the Settings (top-left button in the Preview tab).

When structure sampling is enabled, the visibility of individual types of structures on the preview can be toggled:

When height sampling is enabled, the preview can be toggled between the biome map and a colorized heightmap:

When y-layer intersection sampling is enabled, the preview can also show the blocks on the current y-layer. Additionally, the y-layer one step below is also shown in a lighter color:

Since version 1.1.0, there is also experimental support for opening the preview in-game for a single-player worlds:

What's new in this fork(1.3.2)

• Updated to Minecraft 1.21.11 and later
• Zoom levels — 32px and 64px per chunk, with Ctrl+scroll to zoom in/out
• Preload system — preloads areas beyond the visible range to reduce drag stuttering
• Arrow key panning and Home key center reset
• World analysis engine — region-level biome and height metrics with profile sampling
• Mod compatibility framework — auto-detects mods like TerraFirmaCraft and applies workarounds
• Improved settings UI — reworked to sidebar + page architecture

Moving on the preview

Clicking and dragging on the map-part of the preview tab will move along the x and z axis. This will cause the following load sequence:

• Any biomes that are not yet sampled on the current y-level
• Structures (if enabled)
• Height map (if enabled)
• Adjacent y-layers (if enabled)

Scrolling does not zoom into the map by default (there is a setting to enable scroll-wheel zoom, or use Ctrl+scroll to zoom). By default, scrolling travels along the y-axis. This allows cave biomes to be seen as well. Please note that non-cave biomes span the entire world height beyond that. Alt+scroll always adjusts Y, regardless of zoom mode.

Other features

• Works with mods! Tested with:
  • Terralith
  • Biomes O' Plenty
• Persistent seed storage
• Highlighting specific biomes
• Highly configurable and extendable

Supported version

FAQ

Q: Will older Minecraft versions be supported?

A: No. This fork targets 1.21.11 and later only.

Q: Will Multiplayer be supported?

A: No.

Q: Scrolling does not zoom the preview!

A: By default, scrolling moves the y-level up and down. To change the zoom level, use Ctrl+scroll, or enable "Scroll wheel zooms map" in Settings. To change the visual size of a chunk, go to Settings (top left wrench) -> Resolution.

Q: The preview is completely white for the y-intersections view.

A: The starting y-layer is now set to approximately sea level (Y=64) instead of the build limit. If you still see white, try scrolling down to a lower y-layer.

Q: My CPU is at 100%!

A: You can limit the number of used cores in Settings (top left wrench) -> General. By default, World Preview tries to compute the biome preview / structures / heightmap as quickly as possible. These calculations require a lot of CPU power.

Mod incompatibilities

This mod should be compatible with most mods (including those adding new biomes and dimensions).

TerraFirmaCraft (TFC)

World Preview is compatible with TFC, however, there is a known issue:

The Y intersections view will always be a white screen for all Y levels with TFC, because the TFCChunkGenerator has a dummy implementation for the getBaseColumn method.

To clarify: This doesn't mean that TFC is broken / does something wrong (it clearly works on its own and does its job). It just means that TFC does not provide the specific information World Preview needs in this case.

Adding support for new biomes and structures

New biomes, structures, and more can be registered via the Minecraft datapack mechanism. See the World Preview dataformat docs for more information.

Credits

• Original mod by Caeruleus Draconis & Taiterio
• Community fork maintained for Minecraft 1.21.11 and later
• Licensed under Apache-2.0