This addon allows pack creators to declare their own simple custom portals.
The portals are not like those in the Nether, but are individual blocks.

All of this is explained in the readme documentation automatically generated by the mod when the world is loaded in the path where the scripts should be placed.

The default scripts path is Modpack/kubejs/external_scripts/simp_cm_portal_portals/.

Simple Custom Portal

Add custom portal blocks to your pack: each block teleports to a dimension you choose (e.g. custom dimensions, Nether, End) at the same x, y, z.

For pack creators: define portals in JSON (id, destination, optional base/capsule blocks, sound, usable dimensions, default return). Files go in a configurable directory — default: kubejs/external_scripts/simp_cm_portal_portals/ under the game directory. The path can be changed in the mod config. When the game loads, the mod also writes a PORTALS.md in that folder with the same documentation below. No KubeJS required; the path name is just the default.

Features: optional safe-zone building at destination, one-way portals via usableIn, /simp_cm_portal_reload for live reload without restart.

The rest of this page is the full documentation (same as the auto-generated PORTALS.md, which is created in the same folder where you put the portal JSON scripts).

Config path

Portal definitions are loaded from JSON files in: <game dir>/<externalScriptsPath>/simp_cm_portal_portals/.

externalScriptsPath is set in mod config (default: kubejs/external_scripts). Only .json files are read.

JSON format

Each JSON file can contain one or more portal definitions. Root structure:

• type (required): "simp_cm_portal:portals" or "iska_utils:portals".
• overwritable (optional): currently unused.
• portals (required): array of portal objects. Each entry must have a unique id.

Portal object

• id (required): unique identifier (e.g. "custom_dimensions-portal_void"). Used for the block registry; only portals loaded at game startup get a block. After a reload, only the logic of existing ids is updated.
• destination (required): dimension resource key the portal sends to (e.g. "minecraft:overworld", "custom_dimensions:void").
• baseBlock (optional): block id for the floor of the safe-zone capsule (e.g. "minecraft:stone"). If empty, floor is not replaced.
• capsuleBlock (optional): block id for walls and ceiling of the capsule (e.g. "minecraft:glass"). If empty, walls/ceiling are not built.
• box (optional): hitbox (collision and visual) as a variable-size box centered in the block. Format: "width height depth" as fractions from 0 to 1, space or comma separated. Example: "1 1 1" or omit = full block; "0.5 1 0.5" = half width and depth, full height; "0.5" = cube 0.5×0.5×0.5. Invalid or empty = full block.
• usableIn (optional): array of dimension keys. If non-empty, the portal can only be used when the player is in one of these dimensions. Use for one-way portals (e.g. only ["minecraft:overworld"] so the return portal in the destination does not work).
• defaultReturn (optional): when the player is already in destination and uses a portal without a stored return, they are sent to this dimension. If empty, using the portal from the destination does nothing.
• sound (optional): block sound type for the portal block (place, break, step). Default is glass. See "Supported sounds" below. Example: "rock".

Supported sounds

Valid values for sound (default if omitted or unknown: glass). Examples: rock, glass, wood — full list in the PORTALS.md generated in the same folder as the scripts.

JSON can contain // and /* */ comments; they are stripped before parsing.

Examples

Minimal (two-way, no safe-zone styling):

{
  "type": "simp_cm_portal:portals",
  "portals": [
    {
      "id": "my_portal_void",
      "destination": "custom_dimensions:void"
    }
  ]
}

Two-way with safe-zone, default return and custom sound (e.g. overworld ↔ void):

{
  "type": "simp_cm_portal:portals",
  "portals": [
    {
      "id": "portal_void",
      "destination": "custom_dimensions:void",
      "baseBlock": "minecraft:stone",
      "capsuleBlock": "minecraft:glass",
      "sound": "rock",
      "usableIn": [],
      "defaultReturn": "minecraft:overworld"
    }
  ]
}

One-way (only from overworld to void; return portal does not work):

{
  "type": "simp_cm_portal:portals",
  "portals": [
    {
      "id": "one_way_void",
      "destination": "custom_dimensions:void",
      "baseBlock": "minecraft:stone",
      "capsuleBlock": "minecraft:glass",
      "usableIn": ["minecraft:overworld"],
      "defaultReturn": ""
    }
  ]
}

Custom hitbox (thin pillar, half width/depth, full height):

{
  "type": "simp_cm_portal:portals",
  "portals": [
    {
      "id": "slim_portal",
      "destination": "minecraft:the_nether",
      "box": "0.5 1 0.5"
    }
  ]
}

Other box examples: "1 1 1" full block; "0.5" small centered cube.

Multiple portals in one file:

{
  "type": "simp_cm_portal:portals",
  "portals": [
    {
      "id": "portal_overworld",
      "destination": "minecraft:overworld",
      "baseBlock": "minecraft:grass_block",
      "capsuleBlock": "minecraft:oak_planks",
      "defaultReturn": "custom_dimensions:void"
    },
    {
      "id": "portal_void",
      "destination": "custom_dimensions:void",
      "baseBlock": "minecraft:stone",
      "capsuleBlock": "minecraft:glass",
      "usableIn": ["minecraft:overworld"],
      "defaultReturn": "minecraft:overworld"
    }
  ]
}

Behaviour

• Click: right-click on a portal block to teleport. The target dimension is: the block’s stored return dimension if it has one, otherwise defaultReturn when already in destination, otherwise destination.
• Same coordinates: the destination portal (or capsule) is created at the same x, y, z as the portal you clicked.
• Return portal: when the mod builds a capsule in the destination, it places a portal block of the same type with a stored return dimension (where you came from). That block then always sends you back.
• Capsule only if needed: if in the destination dimension there is already a portal at the same position or with the same return dimension in a 32-block radius, the player is teleported there and no capsule is built.
• Safe zone: when built, the capsule has interior 3×3×4, with floor (baseBlock), walls and ceiling (capsuleBlock), and the return portal at the centre.

Validation before building

Before building the capsule, the mod checks that no block in the zone has:

• the vanilla tag minecraft:features_cannot_replace
• the block is bedrock
• explosion resistance ≥ 3,600,000 (indestructible)

If any of these fail, the player gets an action-bar message (e.g. "Invalid position for portal") and no build/teleport happens.

Command

• /simp_cm_portal_reload (permission level 2): reloads portal definitions from all JSON files in the portals folder (same path where you put the scripts) and refreshes the destination map. Only logic is updated; new ids in JSON do not get new blocks until the game is restarted.

Portals removed from JSON

If a portal block still exists in the world but its id was removed from every JSON (e.g. after a reload), the block does nothing and does not crash: click returns PASS. After a game restart, that block type may no longer exist depending on registration.