UtilityCraft Machine UI Core

UtilityCraft/RP/ui/ui_core.json is the shared JSON UI control library used by UtilityCraft machinery and compatible extensions. It defines the uc namespace and supplies screens, labels, slots, progress displays, resource bars, upgrade tabs, IO configuration, information tabs, toggles, and lower-level helpers.

Do not copy ui_core.json into your addon

UtilityCraft already loads this file from its Resource Pack. Your addon only creates and registers its own UI files, then references the shared elements with @uc.<element>. Duplicating the namespace creates version conflicts and prevents UtilityCraft from updating the shared UI safely.

Dependency contract: the UtilityCraft Resource Pack must be active below or alongside the extension according to the world pack stack. The extension does not bundle another copy of UI Core or its textures.

What the shared controls look like

This is a production UtilityCraft Assembler screen. The title, gray machine screen, energy bar, slot outlines, upgrades, IO tab, and information tab are composed from uc controls.

The texture previews throughout this section are copied into the documentation site only from UtilityCraft's real RP assets. They show the actual pixels used in-game; they are not files an addon should duplicate.

Register only your UI file

Your Resource Pack lists its own file:

RP/ui/_ui_defs.json

{
  "ui_defs": [
    "ui/example_machinery.json"
  ]
}

Then the addon-owned UI uses a different namespace and references UtilityCraft controls:

RP/ui/example_machinery.json

{
  "namespace": "example_ui",

  "crusher_top": {
    "type": "collection_panel",
    "anchor_from": "center",
    "anchor_to": "center",
    "size": [162, 72],
    "offset": [-10, -40],
    "collection_name": "container_items",
    "$item_collection_name": "container_items",
    "controls": [
      { "machine_name@uc.machine_name": {} },
      { "screen@uc.machine_small_screen": {} },
      {
        "description@uc.text_label": {
          "collection_index": 1,
          "offset": [14, 12],
          "size": [48, 48],
          "$text_scale": 0.55
        }
      },
      {
        "energy@uc.energy_bar": {
          "offset": [-101, -13]
        }
      },
      {
        "input@uc.input_slot": {
          "collection_index": 3,
          "offset": [0, 30]
        }
      },
      {
        "progress@uc.progress_display": {
          "collection_index": 2,
          "offset": [28, 23]
        }
      },
      {
        "output@uc.output_slot": {
          "collection_index": 4,
          "offset": [56, 26]
        }
      },
      { "upgrades@uc.upgrades_tab": {} },
      { "io@uc.io_tab": {} },
      {
        "info@uc.info_tab": {
          "$info_description": "ui.example:info.crusher"
        }
      }
    ]
  }
}

The complete UtilityCraft Addon Template includes the chest-screen routing, labels, entities, and container indices required for a working machine.

Element syntax

{
  "local_control_name@uc.shared_element": {
    "collection_index": 4,
    "offset": [20, 24],
    "$custom_variable": "value"
  }
}

Part	Meaning
local_control_name	Name unique inside the current controls array. It does not need to match the shared name.
@uc.shared_element	Inherits the named control from UtilityCraft's uc namespace.
$custom_variable	Parameter intentionally exposed by that shared element.
collection_index	Index in the helper entity's container_items collection. It is a standard JSON UI property, not a UI Core $ variable.
anchor_from, anchor_to, offset, size, layer, visible	Standard JSON UI overrides accepted where appropriate by the inherited control.

The reference tables list custom $variables. Standard JSON UI properties are not repeated in every row.

Collection-index contract

UI Core does not decide which machine value belongs in an inventory slot. The machine helper entity, labels, button items, progress frames, resource display items, and IO buttons must be written to the same indices referenced by the JSON UI.

For example:

Index	Typical content	Control
1	Machine information label	uc.text_label
2	Progress frame item	uc.progress_display
3	Input item	uc.input_slot
4	Output item	uc.output_slot
5–8	Upgrade items	uc.upgrades_tab variables
9+	IO face button items	uc.io_tab direction-index variables

The actual indices are machine-owned. Override every relevant variable when your entity layout differs from a control's defaults.

Reference categories

Category	Contents
Visibility, labels, tooltips, and buttons	Conditional panels, hover text, machine title, dynamic labels, slot hover behavior, and buttons.
Items and slots	Item renderers, progress displays, input/output/fuel/upgrade slots, and the numbered IO outline families.
Bars, grids, and screens	Energy/liquid bars, multi-bars, slot layouts, machine screens, and side panels.
Tabs and IO configuration	Generic toggles, upgrade tab, IO face controls, IO tab, and information tab.
Complete element index	All 100 top-level definitions, inheritance relationships, and public status.

Public versus implementation controls

Names beginning with _, such as uc._slot_visual, are implementation primitives used to build stable public controls. They remain listed because they exist in ui_core.json, but normal extension UIs should prefer their public wrappers. Controls inheriting @common.* or other uc elements are templates, not separate files that must be registered.