352 lines
10 KiB
Markdown
352 lines
10 KiB
Markdown
---
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title: 精确旋转
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category: 巧思案例
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tags:
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- experimental
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- expert
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mentions:
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- QuazChick
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---
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# 精确旋转
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<!--@include: @/wiki/bedrock-wiki-mirror.md-->
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::: tip 格式与最低引擎版本 `1.20.30`
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本教程假定您已具备方块的进阶知识与Molang基础。
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开始前建议先阅读[方块指南](/wiki/blocks/blocks-intro)。
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:::
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::: warning 实验性功能
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需要启用 `Holiday Creator Features` 来触发事件。
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:::
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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。
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*查看常规旋转方式？请前往[此页面](/wiki/blocks/rotatable-blocks)！*
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特性概览:
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- 可附着于方块顶部，具备16种旋转角度
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- 可附着于方块的侧表面（北、东、南、西）
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- 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！
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## 方块模型
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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。
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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:
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- `up_0` (Y旋转角度 = 0)
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- `up_22_5` (Y旋转角度 = 22.5)
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- `up_45` (Y旋转角度 = 45)
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- `up_67_5` (Y旋转角度 = 67.5)
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**上述角度值采用顺时针方向递增**
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这些骨骼除旋转参数外，在结构上通常是互为复制的。
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:::tip
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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。
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:::
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此外，还需一个 `side` 骨骼用于侧表面附着时的定位调整。
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下方展示的"贝壳"模型结构可供参考:
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<Spoiler title="贝壳模型实例">
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::: code-group
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```json [RP/models/blocks/shell.geo.json]
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{
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"format_version": "1.12.0",
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"minecraft:geometry": [
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{
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"description": {
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"identifier": "geometry.shell",
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"texture_width": 16,
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"texture_height": 16,
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"visible_bounds_width": 3,
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"visible_bounds_height": 2.5,
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"visible_bounds_offset": [0, 0.75, 0]
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},
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"bones": [
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{
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"name": "shell",
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"pivot": [0, 0, 0]
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},
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{
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"name": "up_0",
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"parent": "shell",
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"pivot": [0, 0, 0],
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"cubes": [
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{
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"origin": [-3, 0, -3],
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"size": [6, 3, 6],
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"uv": {
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"north": { "uv": [0, 6], "uv_size": [6, 3] },
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"east": { "uv": [0, 6], "uv_size": [6, 3] },
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"south": { "uv": [0, 6], "uv_size": [6, 3] },
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"west": { "uv": [0, 6], "uv_size": [6, 3] },
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"up": { "uv": [6, 6], "uv_size": [-6, -6] },
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"down": { "uv": [6, 6], "uv_size": [-6, -6] }
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}
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}
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]
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},
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{
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"name": "up_22_5",
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"parent": "shell",
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"pivot": [0, 0, 0],
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"rotation": [0, 22.5, 0],
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"cubes": [
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{
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"origin": [-3, 0, -3],
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"size": [6, 3, 6],
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"uv": {
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"north": { "uv": [0, 6], "uv_size": [6, 3] },
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"east": { "uv": [0, 6], "uv_size": [6, 3] },
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"south": { "uv": [0, 6], "uv_size": [6, 3] },
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"west": { "uv": [0, 6], "uv_size": [6, 3] },
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"up": { "uv": [6, 6], "uv_size": [-6, -6] },
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"down": { "uv": [6, 6], "uv_size": [-6, -6] }
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}
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}
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]
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},
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{
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"name": "up_45",
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"parent": "shell",
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"pivot": [0, 0, 0],
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"rotation": [0, 45, 0],
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"cubes": [
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{
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"origin": [-3, 0, -3],
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"size": [6, 3, 6],
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"uv": {
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"north": { "uv": [0, 6], "uv_size": [6, 3] },
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"east": { "uv": [0, 6], "uv_size": [6, 3] },
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"south": { "uv": [0, 6], "uv_size": [6, 3] },
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"west": { "uv": [0, 6], "uv_size": [6, 3] },
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"up": { "uv": [6, 6], "uv_size": [-6, -6] },
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"down": { "uv": [6, 6], "uv_size": [-6, -6] }
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}
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}
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]
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},
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{
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"name": "up_67_5",
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"parent": "shell",
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"pivot": [0, 0, 0],
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"rotation": [0, 67.5, 0],
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"cubes": [
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{
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"origin": [-3, 0, -3],
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"size": [6, 3, 6],
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"uv": {
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"north": { "uv": [0, 6], "uv_size": [6, 3] },
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"east": { "uv": [0, 6], "uv_size": [6, 3] },
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"south": { "uv": [0, 6], "uv_size": [6, 3] },
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"west": { "uv": [0, 6], "uv_size": [6, 3] },
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"up": { "uv": [6, 6], "uv_size": [-6, -6] },
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"down": { "uv": [6, 6], "uv_size": [-6, -6] }
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}
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}
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]
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},
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{
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"name": "side",
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"parent": "shell",
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"pivot": [0, 5, 8],
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"rotation": [90, 0, 0],
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"cubes": [
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{
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"origin": [-3, 5, 8],
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"size": [6, 3, 6],
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"uv": {
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"north": { "uv": [0, 6], "uv_size": [6, 3] },
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"east": { "uv": [0, 6], "uv_size": [6, 3] },
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"south": { "uv": [0, 6], "uv_size": [6, 3] },
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"west": { "uv": [0, 6], "uv_size": [6, 3] },
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"up": { "uv": [6, 6], "uv_size": [-6, -6] },
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"down": { "uv": [6, 6], "uv_size": [-6, -6] }
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}
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}
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]
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}
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]
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}
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]
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}
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```
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:::
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</Spoiler>
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## 基础方块JSON
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下方是待添加高级旋转功能的"贝壳"方块基础定义。
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::: code-group
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```json [BP/blocks/shell.json]
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{
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"format_version": "1.20.30",
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"minecraft:block": {
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"description": {
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"identifier": "wiki:shell",
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"menu_category": {
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"category": "nature"
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}
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},
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"components": {
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// `up` 表面的碰撞/选择框
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"minecraft:collision_box": {
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"origin": [-3, 0, -3],
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"size": [6, 3, 6]
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},
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"minecraft:selection_box": {
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"origin": [-3, 0, -3],
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"size": [6, 3, 6]
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},
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"minecraft:material_instances": {
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"*": {
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"texture": "shell" // 在 `RP/textures/terrain_texture.json` 中定义的短名称
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}
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},
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// 阻止方块附着于 `down` 表面
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"minecraft:placement_filter": {
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"conditions": [
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{
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"allowed_faces": ["up", "side"]
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}
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]
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}
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}
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}
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}
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```
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:::
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## 方块状态
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为实现头颅式旋转机制，需为方块添加2种状态参数：
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::: code-group
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```json [minecraft:block]
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"description": {
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...
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"traits": {
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// 方块附着面 - 默认为 `north`
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"minecraft:placement_position": {
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"enabled_states": ["minecraft:block_face"]
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}
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},
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"states": {
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// 当附着于 `up` 表面时的精确旋转参数
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"wiki:rotation": {
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"values": { "min": 0, "max": 15 } // 使用更方便的定义整数范围的语法
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}
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}
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}
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```
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:::
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## 旋转Molang表达式
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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！
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```c
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// 转换玩家头部Y旋转角度至正值
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t.positive_head_rot = q.head_y_rotation(0) + 360 * (q.head_y_rotation(0) != math.abs(q.head_y_rotation(0)));
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// 计算头部旋转对应的十六分之一圆角（取整）
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t.rotation = math.round(t.positive_head_rot / 22.5);
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// 0与16代表重复旋转（0度与360度），故当值为16时返回0
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return t.rotation != 16 ? t.rotation;
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```
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合并为单行表达式以便嵌入JSON：
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::: code-group
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```json [minecraft:block > components > minecraft:on_player_placing > condition]
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"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;"
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```
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:::
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## 应用旋转
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现在通过Molang表达式动态设定方块属性!
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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`。
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在方块JSON中添加以下组件与事件：
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::: code-group
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```json [minecraft:block]
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"components": {
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...
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"minecraft:on_player_placing": {
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"condition": "q.block_face == 1", // 精确旋转仅作用于 `up` 表面
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"event": "wiki:set_rotation"
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}
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},
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"events": {
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"wiki:set_rotation": {
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"set_block_property": {
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// 应用之前的Molang表达式设置rotation属性
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"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; };"
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}
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}
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}
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```
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:::
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<br>
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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。
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按顺序在方块JSON中添加以下置换条件：
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::: code-group
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```json [minecraft:block]
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"permutations": [
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{
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"condition": "q.block_property('wiki:rotation') >= 4 || q.block_property('minecraft:block_face') == 'east'",
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"components": {
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"minecraft:transformation": { "rotation": [0, -90, 0] }
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}
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},
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{
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"condition": "q.block_property('wiki:rotation') >= 8 || q.block_property('minecraft:block_face') == 'south'",
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"components": {
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"minecraft:transformation": { "rotation": [0, 180, 0] }
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}
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},
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{
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"condition": "q.block_property('wiki:rotation') >= 12 || q.block_property('minecraft:block_face') == 'west'",
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"components": {
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"minecraft:transformation": { "rotation": [0, 90, 0] }
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}
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}
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]
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```
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:::
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## 骨骼可见性
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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。
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在方块组件中加入以下内容：
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::: code-group
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```json [minecraft:block > components]
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"minecraft:geometry": {
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"identifier": "geometry.shell", // 第一步创建的模型
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"bone_visibility": {
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"up_0": "q.block_property('minecraft:block_face') == 'up' && !math |