minecraft-resource-pack

# 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:
```json
"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`

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

Column block (like logs):
```json
{
  "parent": "minecraft:block/cube_column",
  "textures": {
    "end": "mypack:block/my_pillar_top",
    "side": "mypack:block/my_pillar_side"
  }
}
```

Different sides:
```json
{
  "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):
```json
{
  "parent": "minecraft:block/cross",
  "textures": {
    "cross": "mypack:block/my_flower"
  }
}
```

### Custom geometry (elements)
```json
{
  "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
```json
{
  "parent": "minecraft:item/generated",
  "textures": {
    "layer0": "mypack:item/my_item"
  }
}
```

### Held item (in-hand model)
```json
{
  "parent": "minecraft:item/handheld",
  "textures": {
    "layer0": "mypack:item/my_sword"
  }
}
```

### Two-layer item (colored like leather armor)
```json
{
  "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`:
```json
{
  "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`:
```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)
```json
{
  "variants": {
    "": { "model": "mypack:block/my_block" }
  }
}
```

### Facing block (4 rotations)
```json
{
  "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)
```json
{
  "variants": {
    "": [
      { "model": "minecraft:block/grass_block",  "weight": 3 },
      { "model": "minecraft:block/grass_block_2" }
    ]
  }
}
```

### Multipart (slabs, fences, walls)
```json
{
  "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`:
```json
{
  "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`
```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`:
```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
```json
{
  "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`
```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

```bash
# 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:

```bash
# 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