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Applying Constant Effects

easy
scripting
Applying Constant Effects

FORMAT & MIN ENGINE VERSION 1.21.40

This tutorial assumes a basic understanding of blocks, including block states. Check out the blocks guide before starting.

This tutorial aims to show how to apply status effects to entities as long as these entities stand on the block.

Detecting Treaders ​

Block JSON ​

We will need to add a couple things to our code, first let's start with a state that will hold true when stood on, and false otherwise:

minecraft:block > description
json
"states": {
    "wiki:stood_on": [false, true]
}

Now we need to register our custom components to hook onto the stepOn and stepOff events:

minecraft:block > components
json
"minecraft:custom_components": [
    "wiki:detect_treaders"
]

Custom Component Script ​

BP/scripts/detect_treaders.js
js
import { BlockPermutation, GameMode, Player, world } from "@minecraft/server";

/** @type {import("@minecraft/server").BlockCustomComponent} */
const DetectTreadersBlockComponent = {
    onStepOn({ entity, block }) {
        if (entity instanceof Player && entity.getGameMode() === GameMode.creative) return;

        block.setPermutation(
            BlockPermutation.resolve(block.typeId, {
                "wiki:stood_on": true,
            })
        );
    },
    onStepOff({ entity, block }) {
        if (entity instanceof Player && entity.getGameMode() === GameMode.creative) return;

        block.setPermutation(
            BlockPermutation.resolve(block.typeId, {
                "wiki:stood_on": false,
            })
        );
    },
};

world.beforeEvents.worldInitialize.subscribe(({ blockComponentRegistry }) => {
    blockComponentRegistry.registerCustomComponent(
        "wiki:detect_treaders",
        DetectTreadersBlockComponent
    );
});

Applying Effects to Treaders ​

Block JSON ​

We also need the block to tick in order to apply the desired effect every tick. For this, we'll use the permutations array so a custom component is only applied if the block is being stepped on:

minecraft:block
json
"permutations": [
    {
        "condition": "q.block_state('wiki:stood_on')",
        "components": {
            "minecraft:custom_components": ["wiki:detect_treaders", "wiki:wither_treaders"],
            "minecraft:tick": {
                "interval_range": [1, 1],
                "looping": true
            }
        }
    }
]

Custom Component Script ​

Now, let's add our event that will give the entity the wither effect:

BP/scripts/wither_treaders.js
js
import { Entity, GameMode, Player, world } from "@minecraft/server";

/** @type {import("@minecraft/server").BlockCustomComponent} */
const WitherTreadersBlockComponent = {
    onTick(event) {
        const entities = event.dimension.getEntitiesAtBlockLocation(event.block.above().location);

        entities.forEach((entity) => {
            entity.addEffect("minecraft:wither", 2, { amplifier: 2 });
        });
    },
};

world.beforeEvents.worldInitialize.subscribe(({ blockComponentRegistry }) => {
    blockComponentRegistry.registerCustomComponent(
        "wiki:wither_treaders",
        WitherTreadersBlockComponent
    );
});

And done! The code above will trigger the desired status effect as long as the entity is standing on a block.

Example JSON ​

Example Wither Block
BP/blocks/wither_block.json
json
{
    "format_version": "1.21.40",
    "minecraft:block": {
        "description": {
            "identifier": "wiki:wither_block",
            "states": {
                "wiki:stood_on": [false, true]
            }
        },
        "components": {
            "minecraft:loot": "loot_tables/empty.json",
            "minecraft:map_color": "#181818",
            "minecraft:geometry": "geometry.wither_block",
            "minecraft:material_instances": {
                "*": {
                    "texture": "wither_block"
                }
            },
            "minecraft:custom_components": ["wiki:detect_treaders"]
        },
        "permutations": [
            {
                "condition": "q.block_state('wiki:stood_on')",
                "components": {
                    "minecraft:custom_components": ["wiki:detect_treaders", "wiki:wither_treaders"],
                    "minecraft:tick": {
                        "interval_range": [1, 1],
                        "looping": true
                    }
                }
            }
        ]
    }
}
Edit Applying Constant Effects on GitHub