Imported from gabrielmoreira/agent-skills-mirror (mirrors/repos/Jahrome907@minecraft-agent-skills/.codex/skills/minecraft-resource-pack/SKILL.md). Install upstream with npx skills add gabrielmoreira/agent-skills-mirror --skill minecraft-resource-pack. Copyright stays with the author.

Minecraft Resource Pack Skill

What Is a Resource Pack?

A resource pack is a folder (or .zip) that overrides or adds Minecraft's visual and audio assets: textures, models, sounds, language files, fonts, and shaders. No Java or mod loader required. Works on vanilla clients and servers.

Routing Boundaries

• Use when: the deliverable is visual/audio assets (textures, models, sounds, fonts, shaders) in resource-pack format.
• Do not use when: the task requires gameplay logic or runtime behavior changes (use minecraft-datapack, minecraft-plugin-dev, or minecraft-modding).
• Do not use when: the task is server infrastructure/runtime administration (minecraft-server-admin).

Pack Metadata

Use pack_format through 1.21.8. Starting in 1.21.9, pack.mcmeta switches to min_format / max_format instead of the older single-number field. For exact patch targeting, use [major, minor] arrays for both min_format and max_format, including .0 versions such as [75, 0]. A single integer is equivalent to [major, 0] for min_format, while a single integer in max_format allows any minor version on that major line. Do not write decimal JSON numbers.

Directory Layout

my-pack/
├── pack.mcmeta
├── pack.png                   ← 64×64 icon (optional)
└── assets/
    └── minecraft/             ← override vanilla (or <namespace>/ for new packs)
        ├── models/
        │   ├── block/
        │   │   └── stone.json
        │   └── item/
        │       └── diamond_sword.json
        ├── items/              ← 1.21.4+ item model definitions
        │   └── diamond_sword.json
        ├── blockstates/
        │   └── stone.json
        ├── textures/
        │   ├── block/
        │   │   └── stone.png
        │   ├── item/
        │   │   └── diamond_sword.png
        │   ├── gui/
        │   │   └── sprites/
        │   │       └── my_sprite.png
        │   └── entity/
        │       └── zombie/
        │           └── zombie.png
        ├── sounds/
        │   └── custom/
        │       └── my_sound.ogg
        ├── sounds.json
        ├── font/
        │   └── default.json
        ├── lang/
        │   └── en_us.json
        ├── shaders/           ← core shader overrides (advanced)
        └── optifine/          ← OptiFine CIT / CTM (OptiFine only)
            └── cit/
                └── my_item.properties

pack.mcmeta

1.21.8 and earlier

{
  "pack": {
    "pack_format": 64,
    "description": "My Custom Resource Pack v1.0"
  }
}

1.21.9 / 1.21.10

{
  "pack": {
    "min_format": [69, 0],
    "max_format": [69, 0],
    "description": "My Custom Resource Pack v1.0"
  }
}

1.21.11

{
  "pack": {
    "min_format": [75, 0],
    "max_format": [75, 0],
    "description": "My Custom Resource Pack v1.0"
  }
}

26.2

{
  "pack": {
    "min_format": [88, 0],
    "max_format": [88, 0],
    "description": "My Custom Resource Pack v1.0"
  }
}

Block Models

assets/minecraft/models/block/my_cube.json

Full cube — all six faces use the same texture:

{
  "parent": "minecraft:block/cube_all",
  "textures": {
    "all": "minecraft:block/stone"
  }
}

Column block (like logs):

{
  "parent": "minecraft:block/cube_column",
  "textures": {
    "end": "mypack:block/my_pillar_top",
    "side": "mypack:block/my_pillar_side"
  }
}

Different sides:

{
  "parent": "minecraft:block/cube",
  "textures": {
    "up":    "mypack:block/my_block_top",
    "down":  "mypack:block/my_block_bottom",
    "north": "mypack:block/my_block_side",
    "south": "mypack:block/my_block_side",
    "east":  "mypack:block/my_block_side",
    "west":  "mypack:block/my_block_side",
    "particle": "mypack:block/my_block_side"
  }
}

Cross model (flowers, plants):

{
  "parent": "minecraft:block/cross",
  "textures": {
    "cross": "mypack:block/my_flower"
  }
}

Custom geometry (elements)

{
  "credit": "Custom model",
  "ambientocclusion": true,
  "textures": {
    "0": "mypack:block/panel",
    "particle": "mypack:block/panel"
  },
  "elements": [
    {
      "from": [0, 0, 7],
      "to": [16, 16, 9],
      "faces": {
        "north": { "texture": "#0", "uv": [0, 0, 16, 16] },
        "south": { "texture": "#0", "uv": [0, 0, 16, 16] }
      }
    }
  ],
  "display": {
    "thirdperson_righthand": {
      "rotation": [75, 45, 0],
      "translation": [0, 2.5, 0],
      "scale": [0.375, 0.375, 0.375]
    }
  }
}

from and to are in 1/16th block units (0–16). uv is [x1, y1, x2, y2] in 0–16 units.

Item Models

Simple flat item

{
  "parent": "minecraft:item/generated",
  "textures": {
    "layer0": "mypack:item/my_item"
  }
}

Held item (in-hand model)

{
  "parent": "minecraft:item/handheld",
  "textures": {
    "layer0": "mypack:item/my_sword"
  }
}

Two-layer item (colored like leather armor)

{
  "parent": "minecraft:item/generated",
  "textures": {
    "layer0": "minecraft:item/leather_helmet",
    "layer1": "minecraft:item/leather_helmet_overlay"
  }
}

Custom model data overrides (1.21.4 and prior)

Each predicate entry routes to a different model based on custom_model_data:

{
  "parent": "minecraft:item/handheld",
  "textures": {
    "layer0": "minecraft:item/stick"
  },
  "overrides": [
    { "predicate": { "custom_model_data": 1001 }, "model": "mypack:item/magic_wand" },
    { "predicate": { "custom_model_data": 1002 }, "model": "mypack:item/fire_staff" }
  ]
}

1.21.4+ Item Model (new format)

In 1.21.4, Mojang introduced a new item model system. Place model definitions at assets/<namespace>/items/<item_name>.json:

{
  "model": {
    "type": "minecraft:select",
    "property": "minecraft:custom_model_data",
    "fallback": {
      "type": "minecraft:model",
      "model": "minecraft:item/stick"
    },
    "cases": [
      {
        "when": 1001,
        "model": { "type": "minecraft:model", "model": "mypack:item/magic_wand" }
      }
    ]
  }
}

Blockstate Definitions

Simple block (no variants)

{
  "variants": {
    "": { "model": "mypack:block/my_block" }
  }
}

Facing block (4 rotations)

{
  "variants": {
    "facing=north": { "model": "mypack:block/my_block" },
    "facing=south": { "model": "mypack:block/my_block",  "y": 180 },
    "facing=east":  { "model": "mypack:block/my_block",  "y": 90  },
    "facing=west":  { "model": "mypack:block/my_block",  "y": 270 }
  }
}

Random texture (multipart)

{
  "variants": {
    "": [
      { "model": "minecraft:block/grass_block",  "weight": 3 },
      { "model": "minecraft:block/grass_block_2" }
    ]
  }
}

Multipart (slabs, fences, walls)

{
  "multipart": [
    { "apply": { "model": "mypack:block/my_slab_bottom" }, "when": { "type": "bottom" } },
    { "apply": { "model": "mypack:block/my_slab_top"    }, "when": { "type": "top"    } },
    { "apply": { "model": "mypack:block/my_block"        }, "when": { "type": "double" } }
  ]
}

Textures

• Format: PNG, RGBA (32-bit)
• Standard block/item size: 16×16 px
• Textures can be larger (32×32, 64×64) — Minecraft scales them, but stick to powers of 2
• Animation requires height = N × width (e.g., 16×64 for 4 frames)
• Place block textures in assets/<namespace>/textures/block/
• Place item textures in assets/<namespace>/textures/item/
• All textures are referenced without the .png extension in JSON

Animated texture MCMETA

assets/minecraft/textures/block/fire_0.png.mcmeta:

{
  "animation": {
    "frametime": 2,
    "frames": [0, 1, 2, 3, 4, 5, 6, 7]
  }
}

If frames is omitted, all frames play sequentially. frametime is in game ticks (default 1).

GUI sprites (1.20.2+)

Place sprites at assets/minecraft/textures/gui/sprites/<category>/<name>.png. Reference them with <category>/<name> in code/JSON.

Sounds

assets/minecraft/sounds.json

{
  "my_sound.play": {
    "sounds": [
      { "name": "mypack:custom/my_sound", "volume": 1.0, "pitch": 1.0, "weight": 1 },
      { "name": "mypack:custom/my_sound_alt", "weight": 2 }
    ],
    "category": "players"
  },
  "entity.player.levelup": {
    "replace": true,
    "sounds": [
      { "name": "mypack:custom/levelup_replaced", "volume": 0.75, "pitch": 1.0 }
    ]
  }
}

• Sound files go in assets/<namespace>/sounds/ as .ogg files (Vorbis encoded)
• Use "replace": true to replace vanilla sounds instead of adding to them
• Categories: master, music, record, weather, block, hostile, neutral, player, ambient, voice

Language Files

assets/minecraft/lang/en_us.json:

{
  "block.mypack.my_block": "My Custom Block",
  "item.mypack.my_item": "Magic Wand",
  "entity.mypack.my_mob": "Forest Guardian",
  "death.attack.mypack.laser": "%1$s was zapped by %2$s"
}

• Use the exact translation key format for your mod/datapack namespace
• File name is the locale code (e.g., fr_fr.json, de_de.json)
• Always provide en_us.json as the primary fallback

Fonts

assets/minecraft/font/default.json — add glyph

{
  "providers": [
    {
      "type": "bitmap",
      "file": "mypack:font/icons.png",
      "ascent": 8,
      "height": 9,
      "chars": ["\uE000", "\uE001", "\uE002"]
    }
  ]
}

Custom icons via private use area (U+E000–U+F8FF). Reference in text with \uE000. The icons.png must have each character cell height pixels tall.

OptiFine CIT (Custom Item Textures)

OptiFine-only feature. Does not work in vanilla or Iris.

assets/minecraft/optifine/cit/my_sword.properties

type=item
items=minecraft:diamond_sword
texture=my_sword_texture.png
model=my_sword_model
nbt.display.Name=ipattern:*Excalibur*

Common CIT properties:

• type=item — item texture override
• type=enchantment — custom enchantment glint
• type=armor — armor overlay
• items= — comma-separated item IDs
• damage= — damage range (e.g., 0-50%)
• nbt.display.Name=ipattern:*text* — NBT name filter
• texture= — PNG file (relative to .properties file)
• model= — JSON model file (relative)

Iris Shaders (Resource Pack Method)

Iris shaders live inside a resource pack at:

assets/iris/
    shaders/
        core/
            rendertype_terrain.vsh    ← vertex shader override
            rendertype_terrain.fsh    ← fragment shader override

Full shader pack distribution uses the .zip format with a shaders/ root folder (not inside assets/). Resource pack shader overrides target specific render types.

Installation

# Singleplayer: place in
~/.minecraft/resourcepacks/my-pack/
# or
~/.minecraft/resourcepacks/my-pack.zip

# Server-side (forces on clients):
# Set in server.properties:
resource-pack=https://example.com/my-pack.zip
resource-pack-sha1=<sha1 hash>
resource-pack-prompt={"text":"Required pack","color":"gold"}

Common Issues

Validator Script

Use the bundled validator script before shipping a resource-pack update:

# Run from the installed skill directory (for example `.claude/skills/minecraft-resource-pack`):
./scripts/validate-resource-pack.sh --root /path/to/resource-pack

# Strict mode treats warnings as failures:
./scripts/validate-resource-pack.sh --root /path/to/resource-pack --strict

What it checks:

• JSON validity for pack.mcmeta and assets/**/*.json
• Model/blockstate/font/sounds references resolve to real files
• Every *.png.mcmeta has a matching *.png

References

• Minecraft Wiki — Resource pack: https://minecraft.wiki/w/Resource_pack
• Minecraft Wiki — Model: https://minecraft.wiki/w/Tutorials/Models
• Minecraft Wiki — Blockstates: https://minecraft.wiki/w/Blockstate_(Java_Edition)
• Pack format history: https://minecraft.wiki/w/Pack_format
• Misode's model viewer: https://misode.github.io/
• OptiFine CIT guide: https://optifine.readthedocs.io/cit.html