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 Format Numbers (1.21.x)

Minecraft Version	pack_format
1.21 / 1.21.1	34
1.21.2 / 1.21.3	42
1.21.4	46
1.21.5	55

Use supported_formats for broad compatibility:

"supported_formats": { "min_inclusive": 34, "max_inclusive": 55 }

---

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
        ├── 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

{
  "pack": {
    "pack_format": 55,
    "supported_formats": { "min_inclusive": 34, "max_inclusive": 55 },
    "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

Problem	Cause	Fix
Model not showing	Wrong JSON path or syntax error	Check assets/<namespace>/models/ path; validate JSON
Black/pink checkerboard	Texture path wrong or missing	Check textures/ path, file extension not in JSON
Blockstate not applying	Wrong state property name	Match exact property names from /blockdata
Animation not working	Wrong MCMETA location	Must be same folder as texture, named texture.png.mcmeta
Custom sound not playing	Not in sounds.json	Register sound event in sounds.json, match namespace
Pack not loading	Wrong pack_format	Update pack.mcmeta for current MC version

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