Question 1

What does this tool convert?

Accepted Answer

This tool converts Minecraft resource pack item model files between the pre-1.21.4 format (using custom_model_data predicate overrides in models/item/*.json) and the 1.21.4+ item definition format (using items/*.json with range_dispatch on custom_model_data, threshold entries, condition, and select nodes). It supports all item types including single-state items, bows, crossbows, fishing rods, shields, clocks, and compasses.

Question 2

Which item types are supported?

Accepted Answer

All Minecraft item types are supported: regular single-state items (swords, tools, blocks, etc.), bows (with pulling animation states and use_duration), crossbows (with pulling, charged arrow, and charged rocket states via charge_type select), fishing rods (with cast state via fishing_rod/cast condition), shields (with blocking state via using_item condition), clocks (with time animation across 64 states), and compasses (with angle animation across 32 states).

Question 3

How do I use this converter?

Accepted Answer

1. Choose the conversion direction using the swap button (pre-1.21.4 to 1.21.4+ or vice versa). 2. Paste your JSON into the left input area or drag and drop a .json file. 3. The conversion happens automatically. 4. Copy or download the result from the right output area. The tool auto-detects the item type (bow, crossbow, fishing rod, shield, clock, compass, or single-state).

Question 4

What changed in Minecraft 1.21.4?

Accepted Answer

In Minecraft 1.21.4, Mojang replaced the old item model system (models/item/*.json with predicate-based overrides) with a new item definition system (items/*.json using tree-based nodes like range_dispatch, condition, and select). The custom_model_data predicate was replaced with a range_dispatch property using threshold entries. This breaking change requires resource pack creators to update their item model files to the new format.

Question 5

How to convert custom_model_data to range_dispatch?

Accepted Answer

In the old format, custom_model_data was a predicate inside overrides: {"predicate": {"custom_model_data": 1}, "model": "item/custom"}. In the new 1.21.4+ format, this becomes a range_dispatch node: {"type": "range_dispatch", "property": "custom_model_data", "entries": [{"threshold": 1, "model": {"type": "model", "model": "item/custom"}}]}. This tool handles the conversion automatically for all item types.

Question 6

How to update a Minecraft resource pack to 1.21.4?

Accepted Answer

To update a resource pack to 1.21.4+, you need to convert item model files from the old models/item/ format with custom_model_data overrides to the new items/ format using range_dispatch with threshold entries. This tool automates that conversion. Paste your old JSON file, and it generates the new 1.21.4+ format. For multi-state items like bows, crossbows, and fishing rods, the tool correctly generates the condition and select tree nodes.

Minecraft Custom Model Data Converter

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