---
title: 精确旋转
category: 巧思案例
tags:
- experimental
- expert
mentions:
- QuazChick
---
# 精确旋转
::: tip 格式与最低引擎版本 `1.20.30`
本教程假定您已具备方块的进阶知识与Molang基础。
开始前建议先阅读[方块指南](/wiki/blocks/blocks-intro)。
:::
::: warning 实验性功能
需要启用 `Holiday Creator Features` 来触发事件。
:::
本教程将引导您实现可支持次级方位旋转的方块（如爬行者头颅与告示牌），通过一个包含此类旋转类型的"贝壳"方块作为实例进行讲解。
*查看常规旋转方式？请前往[此页面](/wiki/blocks/rotatable-blocks)！*
特性概览:
- 可附着于方块顶部，具备16种旋转角度
- 可附着于方块的侧表面（北、东、南、西）
- 旋转行为与原版生物头颅一致，且无需依赖方块实体性能消耗！
## 方块模型
要实现更精确的旋转机制，您的方块模型需额外添加若干骨骼节点。
实现地面精确旋转需要4个基础骨骼节点，每个对应不同的Y轴旋转角度:
- `up_0` (Y旋转角度 = 0)
- `up_22_5` (Y旋转角度 = 22.5)
- `up_45` (Y旋转角度 = 45)
- `up_67_5` (Y旋转角度 = 67.5)
**上述角度值采用顺时针方向递增**
这些骨骼除旋转参数外，在结构上通常是互为复制的。
:::tip
建议将所有骨骼的枢轴点设置于 `[0, 0, 0]` ，以确保其围绕方块中心旋转。
:::
此外，还需一个 `side` 骨骼用于侧表面附着时的定位调整。
下方展示的"贝壳"模型结构可供参考:
::: code-group
```json [RP/models/blocks/shell.geo.json]
{
"format_version": "1.12.0",
"minecraft:geometry": [
{
"description": {
"identifier": "geometry.shell",
"texture_width": 16,
"texture_height": 16,
"visible_bounds_width": 3,
"visible_bounds_height": 2.5,
"visible_bounds_offset": [0, 0.75, 0]
},
"bones": [
{
"name": "shell",
"pivot": [0, 0, 0]
},
{
"name": "up_0",
"parent": "shell",
"pivot": [0, 0, 0],
"cubes": [
{
"origin": [-3, 0, -3],
"size": [6, 3, 6],
"uv": {
"north": { "uv": [0, 6], "uv_size": [6, 3] },
"east": { "uv": [0, 6], "uv_size": [6, 3] },
"south": { "uv": [0, 6], "uv_size": [6, 3] },
"west": { "uv": [0, 6], "uv_size": [6, 3] },
"up": { "uv": [6, 6], "uv_size": [-6, -6] },
"down": { "uv": [6, 6], "uv_size": [-6, -6] }
}
}
]
},
{
"name": "up_22_5",
"parent": "shell",
"pivot": [0, 0, 0],
"rotation": [0, 22.5, 0],
"cubes": [
{
"origin": [-3, 0, -3],
"size": [6, 3, 6],
"uv": {
"north": { "uv": [0, 6], "uv_size": [6, 3] },
"east": { "uv": [0, 6], "uv_size": [6, 3] },
"south": { "uv": [0, 6], "uv_size": [6, 3] },
"west": { "uv": [0, 6], "uv_size": [6, 3] },
"up": { "uv": [6, 6], "uv_size": [-6, -6] },
"down": { "uv": [6, 6], "uv_size": [-6, -6] }
}
}
]
},
{
"name": "up_45",
"parent": "shell",
"pivot": [0, 0, 0],
"rotation": [0, 45, 0],
"cubes": [
{
"origin": [-3, 0, -3],
"size": [6, 3, 6],
"uv": {
"north": { "uv": [0, 6], "uv_size": [6, 3] },
"east": { "uv": [0, 6], "uv_size": [6, 3] },
"south": { "uv": [0, 6], "uv_size": [6, 3] },
"west": { "uv": [0, 6], "uv_size": [6, 3] },
"up": { "uv": [6, 6], "uv_size": [-6, -6] },
"down": { "uv": [6, 6], "uv_size": [-6, -6] }
}
}
]
},
{
"name": "up_67_5",
"parent": "shell",
"pivot": [0, 0, 0],
"rotation": [0, 67.5, 0],
"cubes": [
{
"origin": [-3, 0, -3],
"size": [6, 3, 6],
"uv": {
"north": { "uv": [0, 6], "uv_size": [6, 3] },
"east": { "uv": [0, 6], "uv_size": [6, 3] },
"south": { "uv": [0, 6], "uv_size": [6, 3] },
"west": { "uv": [0, 6], "uv_size": [6, 3] },
"up": { "uv": [6, 6], "uv_size": [-6, -6] },
"down": { "uv": [6, 6], "uv_size": [-6, -6] }
}
}
]
},
{
"name": "side",
"parent": "shell",
"pivot": [0, 5, 8],
"rotation": [90, 0, 0],
"cubes": [
{
"origin": [-3, 5, 8],
"size": [6, 3, 6],
"uv": {
"north": { "uv": [0, 6], "uv_size": [6, 3] },
"east": { "uv": [0, 6], "uv_size": [6, 3] },
"south": { "uv": [0, 6], "uv_size": [6, 3] },
"west": { "uv": [0, 6], "uv_size": [6, 3] },
"up": { "uv": [6, 6], "uv_size": [-6, -6] },
"down": { "uv": [6, 6], "uv_size": [-6, -6] }
}
}
]
}
]
}
]
}
```
:::
## 基础方块JSON
下方是待添加高级旋转功能的"贝壳"方块基础定义。
::: code-group
```json [BP/blocks/shell.json]
{
"format_version": "1.20.30",
"minecraft:block": {
"description": {
"identifier": "wiki:shell",
"menu_category": {
"category": "nature"
}
},
"components": {
// `up` 表面的碰撞/选择框
"minecraft:collision_box": {
"origin": [-3, 0, -3],
"size": [6, 3, 6]
},
"minecraft:selection_box": {
"origin": [-3, 0, -3],
"size": [6, 3, 6]
},
"minecraft:material_instances": {
"*": {
"texture": "shell" // 在 `RP/textures/terrain_texture.json` 中定义的短名称
}
},
// 阻止方块附着于 `down` 表面
"minecraft:placement_filter": {
"conditions": [
{
"allowed_faces": ["up", "side"]
}
]
}
}
}
}
```
:::
## 方块状态
为实现头颅式旋转机制，需为方块添加2种状态参数：
::: code-group
```json [minecraft:block]
"description": {
...
"traits": {
// 方块附着面 - 默认为 `north`
"minecraft:placement_position": {
"enabled_states": ["minecraft:block_face"]
}
},
"states": {
// 当附着于 `up` 表面时的精确旋转参数
"wiki:rotation": {
"values": { "min": 0, "max": 15 } // 使用更方便的定义整数范围的语法
}
}
}
```
:::
## 旋转Molang表达式
相较于逐个定义每个 `wiki:rotation` 值的范围，运用[复合Molang表达式](https://learn.microsoft.com/en-us/minecraft/creator/reference/content/molangreference/examples/molangconcepts/molangintroduction#simple-vs-complex-expressions)配合除法运算可高效实现需求！
```c
// 转换玩家头部Y旋转角度至正值
t.positive_head_rot = q.head_y_rotation(0) + 360 * (q.head_y_rotation(0) != math.abs(q.head_y_rotation(0)));
// 计算头部旋转对应的十六分之一圆角（取整）
t.rotation = math.round(t.positive_head_rot / 22.5);
// 0与16代表重复旋转（0度与360度），故当值为16时返回0
return t.rotation != 16 ? t.rotation;
```
合并为单行表达式以便嵌入JSON：
::: code-group
```json [minecraft:block > components > minecraft:on_player_placing > condition]
"condition": "t.positive_head_rot = q.head_y_rotation(0) + 360 * (q.head_y_rotation(0) != math.abs(q.head_y_rotation(0))); t.rotation = math.round(t.positive_head_rot / 22.5); return t.rotation != 16 ? t.rotation;"
```
:::
## 应用旋转
现在通过Molang表达式动态设定方块属性!
通过事件在玩家放置方块时更新方块属性。此事件上下文可访问 `q.block_face` 与 `q.head_y_rotation`。
在方块JSON中添加以下组件与事件：
::: code-group
```json [minecraft:block]
"components": {
...
"minecraft:on_player_placing": {
"condition": "q.block_face == 1", // 精确旋转仅作用于 `up` 表面
"event": "wiki:set_rotation"
}
},
"events": {
"wiki:set_rotation": {
"set_block_property": {
// 应用之前的Molang表达式设置rotation属性
"wiki:rotation": "q.block_face == 1 ? { t.positive_head_rot = q.head_y_rotation(0) + 360 * (q.head_y_rotation(0) != math.abs(q.head_y_rotation(0))); t.block_rotation = math.round(t.positive_head_rot / 22.5); return t.block_rotation != 16 ? t.block_rotation; };"
}
}
}
```
:::
接着，使用[置换](/wiki/blocks/block-permutations)定义基础朝向旋转，由模型中的精细骨骼进一步细化。
按顺序在方块JSON中添加以下置换条件：
::: code-group
```json [minecraft:block]
"permutations": [
{
"condition": "q.block_property('wiki:rotation') >= 4 || q.block_property('minecraft:block_face') == 'east'",
"components": {
"minecraft:transformation": { "rotation": [0, -90, 0] }
}
},
{
"condition": "q.block_property('wiki:rotation') >= 8 || q.block_property('minecraft:block_face') == 'south'",
"components": {
"minecraft:transformation": { "rotation": [0, 180, 0] }
}
},
{
"condition": "q.block_property('wiki:rotation') >= 12 || q.block_property('minecraft:block_face') == 'west'",
"components": {
"minecraft:transformation": { "rotation": [0, 90, 0] }
}
}
]
```
:::
## 骨骼可见性
并非所有骨骼节点始终可见，因此需利用 `minecraft:geometry` 的骨骼可见性属性精确控制渲染。多个骨骼存在的目的是因为 `minecraft:transformation` 仅支持90度的整数倍旋转，而精确旋转需要22.5度的增量。
在方块组件中加入以下内容：
::: code-group
```json [minecraft:block > components]
"minecraft:geometry": {
"identifier": "geometry.shell", // 第一步创建的模型
"bone_visibility": {
"up_0": "q.block_property('minecraft:block_face') == 'up' && !math