Falling-Item Crafting

Topics covered: recipe checks, item entities, entity spawn events, and level tick events. Mods and versions used:

1. rhino-forge-2001.2.2-build.18
2. architectury-9.2.14-forge
3. kubejs-forge-2001.6.5-build.14
4. probejs-6.0.1-forge

Full Code

Below is the full code with partial comment explanations. For full walkthrough details, check Gu-meng's Bilibili video.

// Record data for falling item entities
let itemFallList = {};
// Recipe list
let fallItem = [
    {
        inputItem: "minecraft:cobblestone",
        outputItem: 'minecraft:gravel',
        spaceBetween: 10
    }
]

EntityEvents.spawned("item", event => {
    /**
     * @type {Internal.ItemEntity}
     */
    let itemEntity = event.getEntity();
    fallItem.forEach(value => {
        // Check the input item
        if (itemEntity.getItem().getId() != value.inputItem) return;
        // Set pickup delay to 32767 so it cannot merge (side effect: cannot be picked up)
        itemEntity.pickUpDelay = 32767;
        // Record item count
        let count = itemEntity.getNbt().get("Item").getInt("Count")
         // Save values
        itemFallList[itemEntity.getUuid()] = {
            dimension: event.getLevel().getDimension(),
            y: itemEntity.getY(),
            output: value.outputItem,
            count: count,
            spaceBetween: value.spaceBetween
        }
    })
})

LevelEvents.tick(event => {
    if (event.server.tickCount % 5 != 0) return
    if (Object.keys(itemFallList).length == 0) return
    for (let key in itemFallList) {
        let fallValue = itemFallList[key];
        if (fallValue.dimension == event.getLevel().getDimension()) {
            try {
                let entity = event.getLevel().getEntity(key)
                if (entity.onGround()) {
                    if (fallValue.y - entity.getY() >= fallValue.spaceBetween) {
                        entity.setItem(Item.of(fallValue.output, fallValue.count))
                    }
                    entity.pickUpDelay = 20;
                    delete itemFallList[key]
                }
            } catch (e) {
                console.warn(e);
                delete itemFallList[key]
            }
        }
    }
})

Notes

1. Recipe checks are string-based, not ItemStack, so NBT cannot be checked directly. Modify this if needed.
2. This project is only an example; many parts are not necessarily optimal and can be improved.
3. If you improve this project, you can upload your revised code to the .
4. You can copy and use this code directly. To add recipes, edit the fallItem array.
5. For cases like water pushing items upward before they fall, you can track each item's highest y value in the level tick handler.