# hbm:pick_one

Selects one matching marker for `result` and replaces the others from `fallback`.

## Selection across chunks

Candidate selection covers the whole template piece, including when it crosses chunk boundaries. Every chunk uses the same selected marker.

## Fields

| Field | Meaning and default |
| - | - |
| `processor_type` | Selects this processor. |
| `marker` | Block state marking candidate positions. |
| `marker.id` | Registered block ID. |
| `marker.properties` (Optional) | Block-state property names and string values. |
| `result` | Block state placed at one selected marker. |
| `result.id` | Registered block ID. |
| `result.properties` (Optional) | Block-state property names and string values. |
| `fallback` | Block-state choices for the remaining markers; an empty list leaves them in place. |
| `fallback.id` | Registered block ID. |
| `fallback.properties` (Optional) | Block-state property names and string values. |

## Example

Custom processor list: `data/example/worldgen/processor_list/single_crate.json`.

```json
{
  "processors": [
    {
      "processor_type": "hbm:pick_one",
      "marker": "minecraft:barrier",
      "result": "hbm:crate_jungle",
      "fallback": [
        "minecraft:air"
      ]
    }
  ]
}
```