Triggering effects¶

Every recipe here is a complete, copy-pasteable way to fire an effect from a game event. They build on Your first datapack, from zero: the files live in the same mymap pack, and the namespace is your own. Run /reload after adding or editing any of them.

Permissions. Functions run at permission level 2 (gamemaster) by default, exactly what the mutating /vfx commands (play, playat, playentity, stop, set) require. That is why a function can play an effect for a player who is not an operator — the permission belongs to the function, not the viewer. Typing the same command in chat still needs op.

1. Play an effect from a function¶

data/mymap/function/effects/blur.mcfunction:

vfx play vfxweaver:blur {[radius:8]} @s

Run it in game with /function mymap:effects/blur (it affects the executing player; run it from a command block or execute as to pick someone else).

2. Play an effect when the world loads¶

Handy for smoke tests. Register a load function tag so the game runs it once on world load.

data/mymap/function/setup.mcfunction:

tellraw @a {"text":"[mymap] VFX effect pack loaded","color":"green"}

data/minecraft/tags/function/load.json:

{ "values": ["mymap:setup"] }

3. Play an effect on first join (advancement)¶

An advancement with the minecraft:tick trigger is granted on the first tick a player is in the world; its reward function runs once, as that player.

data/mymap/advancement/first_join.json:

{
    "criteria": {
        "tick": { "trigger": "minecraft:tick" }
    },
    "rewards": { "function": "mymap:on_first_join" }
}

data/mymap/function/on_first_join.mcfunction:

vfx play vfxweaver:screen_flash {[color_r:0.2],[color_g:0.8],[color_b:1.0],[alpha:0.4]} @s

4. Play an effect when the player takes damage (scoreboard tick check)¶

This fires every time health drops, so it repeats. It needs two scoreboard objectives and three functions.

data/mymap/function/setup.mcfunction (extend the load recipe's file):

scoreboard objectives add vfx.health dummy
scoreboard objectives add vfx.prev dummy

data/mymap/function/tick.mcfunction (runs every tick):

execute as @a at @s run function mymap:check_damage

data/mymap/function/check_damage.mcfunction (runs as one player):

scoreboard players operation @s vfx.prev = @s vfx.health
execute store result score @s vfx.health run data get entity @s Health
execute if score @s vfx.health < @s vfx.prev run function mymap:on_damage

data/mymap/function/on_damage.mcfunction:

vfx play vfxweaver:screen_flash {[color_r:1.0],[color_g:0.1],[color_b:0.1],[alpha:0.5]} @s

Register the tick function in data/minecraft/tags/function/tick.json:

{ "values": ["mymap:tick"] }

vfx.health holds the health read this tick, vfx.prev the value from the tick before; when the current value drops below the previous one, the player was hurt.

5. Play an effect when the player kills an entity (repeatable advancement)¶

Advancements are normally granted once, so the reward function revokes it again — that makes the trigger repeatable.

data/mymap/advancement/zombie_kill.json:

{
    "criteria": {
        "killed": {
            "trigger": "minecraft:player_killed_entity",
            "conditions": { "entity": { "type": "minecraft:zombie" } }
        }
    },
    "rewards": { "function": "mymap:on_zombie_kill" }
}

data/mymap/function/on_zombie_kill.mcfunction:

vfx play vfxweaver:camera_shake {[amplitude_y:0.3],[frequency:20]} @s
advancement revoke @s only mymap:zombie_kill

Change the entity.type to match any mob, or drop the conditions block to fire on any kill.

6. Play on a player, at a world position, or on an entity¶

The three targets are three different commands.

# 1) On a player (screen-space / world overlays that follow them)
vfx play vfxweaver:blur {[radius:8]} @s

# 2) On every connected player
vfx play vfxweaver:blur {[radius:8]} @a

# 3) At an exact world position (light_beam, block_tint, pulse_ring, ...)
vfx playat vfxweaver:light_beam 8 70 8 {[radius:2],[top_scale:2]}

# 4) At an entity's position (relative coordinates from execute)
execute at @e[type=minecraft:zombie,limit=1] run vfx playat vfxweaver:light_beam ~ ~ ~ {[radius:2]}

# 5) On an entity (entity_tint / entity_outline / entity_displace, targeted by selector)
vfx playentity vfxweaver:entity_outline @e[type=minecraft:zombie,limit=1] {[width:0.12]}

/vfx playat takes absolute or ~ relative coordinates, so recipe 4 works wherever the entity stands. /vfx playentity sends the effect to the executing player by default; add a trailing player selector to show it to others (e.g. ... @e[...] @a).

7. Drive a param from a scoreboard¶

A definition can read a scoreboard value live; the parameter follows the score with no command loop. Put this in data/mymap/vfx/tension_blur.json:

{
    "type": "blur",
    "persistent": true,
    "fade_ticks": 10,
    "params": {
        "radius": { "bind": "scoreboard", "objective": "mymap.tension", "range": 10, "scale": 20 }
    }
}

Then:

scoreboard objectives add mymap.tension dummy
scoreboard players set @s mymap.tension 5
vfx play mymap:tension_blur

The blur radius tracks the score from 0 to 20 as the score runs 0 to 10 (score / range × scale), and updates on its own while the effect is persistent. Stop it with vfx stop mymap:tension_blur. On a dedicated server the value is pushed to clients, so it works for players who do not have the objective displayed.

8. Stop what you started¶

vfx stop vfxweaver:blur
vfx stop mymap:tension_blur @a
vfx stop @a

/vfx stop <effect> stops every instance of that effect; /vfx stop [<player>] stops every active effect of a player (default: the executor). See Commands for the full surface.