Create the UI File

A working machine screen needs three connections:

_ui_defs.json -> first_machine_ui.json -> chest_screen.json route

The UI definition loads your controls. The chest-screen route selects those controls when Minecraft opens the Example Thermal Crusher helper entity.

1. Create an addon-owned namespace

Create this file:

RP/ui/first_machine_ui.json

{
  "namespace": "first_machine_ui",

  "utility_panel_template": {
    "type": "panel",
    "$machine_top|default": "first_machine_ui.crusher_top",
    "controls": [
      {
        "container_gamepad_helpers@common.container_gamepad_helpers": {}
      },
      {
        "flying_item_renderer@common.flying_item_renderer": {
          "layer": 40
        }
      },
      {
        "selected_item_details_factory@common.selected_item_details_factory": {}
      },
      {
        "item_lock_notification_factory@common.item_lock_notification_factory": {}
      },
      {
        "root_panel@common.root_panel": {
          "layer": 1,
          "controls": [
            {
              "common_panel@common.common_panel": {}
            },
            {
              "chest_panel": {
                "type": "panel",
                "layer": 5,
                "controls": [
                  {
                    "machine_top@$machine_top": {}
                  },
                  {
                    "inventory_panel_bottom_half_with_label@common.inventory_panel_bottom_half_with_label": {}
                  },
                  {
                    "hotbar_grid@common.hotbar_grid_template": {}
                  },
                  {
                    "inventory_take_progress_icon_button@common.inventory_take_progress_icon_button": {}
                  }
                ]
              }
            },
            {
              "inventory_selected_icon_button@common.inventory_selected_icon_button": {}
            },
            {
              "gamepad_cursor@common.gamepad_cursor_button": {}
            }
          ]
        }
      }
    ]
  },

  "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": []
  },

  "crusher_utility_panel@first_machine_ui.utility_panel_template": {
    "$machine_top": "first_machine_ui.crusher_top"
  }
}

first_machine_ui belongs to the addon. It must be unique; do not name it uc, chest, or common because those namespaces already belong to other UI files.

The utility_panel_template retains Minecraft's player inventory, hotbar, item tooltip, controller helpers, cursor, and item-transfer behavior. Later pages only change crusher_top, the standard 162 × 72 machine area.

2. Load the file

Add the new path to ui_defs. Keep example_machinery.json because the other template machines still use it.

RP/ui/_ui_defs.json

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

Every path is relative to the Resource Pack root and uses forward slashes.

3. Route the crusher to the new screen

Open RP/ui/chest_screen.json. Find the route whose requires value contains the Example Thermal Crusher entity name. Change its $screen_content value:

RP/ui/chest_screen.json

{
  "requires": "($temp_container_title = 'entity.utilitycraft:example_thermal_crusher.name')",
  "$screen_content": "first_machine_ui.crusher_utility_panel",
  "$screen_bg_content": "common.screen_background"
}

Do not add a second route for the same entity title. Replace the existing crusher route so only one screen can match it.

The route has two different identifiers:

Value	Meaning
entity.utilitycraft:example_thermal_crusher.name	Localization key used as the helper entity's container title.
first_machine_ui.crusher_utility_panel	namespace.control to display when that title matches.

The template already contains the required entity localization:

RP/texts/en_US.lang

entity.utilitycraft:example_thermal_crusher.name=Example Thermal Crusher

The requires expression uses the localization key, not the visible English text. This allows the same route to work in every language.

4. Test the route

Build and load both UtilityCraft and the template Resource Pack, then open the crusher. At this stage the custom top area is intentionally empty, but the player inventory and hotbar should still appear.

If Minecraft opens a normal chest instead, verify:

• first_machine_ui.json is listed in _ui_defs.json;
• the namespace and control name match exactly;
• the crusher has only one matching route;
• the entity localization key matches the route;
• the JSON UI content log contains no parse error.

Continue with Display input and output.