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docs/mconline/15-玩法组件教程/15-自定义特征和特征规则/9-了解加权随机特征规则.md

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+---
+front: https://nie.res.netease.com/r/pic/20211104/69055361-2e7a-452f-8b1a-f23e1262a03a.jpg
+hard: 高级
+time: 10分钟
+---
+
+# 了解加权随机特征规则
+
+加权随机特征可以用于按比重生成多种特征。我们使用加权随机特征来生成一些各种样式的水井。
+
+## 使用编辑器导出多种水井结构
+
+![](./images/16.9_save_structures.png)
+
+我们在地图编辑器中制作多种水井，并将其导出。导出的结构会自动进入行为包的`structures/<namespace>`文件夹中。这里，由于我们在编辑器中设置的命名空间为`tutorial_demo`，我们的结构会放置于`structures/tutorial_demo`文件夹中。
+
+## 使用结构特征配置水井
+
+我们使用中国版的结构特征来制作四种水井的特征。
+
+```json
+{
+  "format_version": "1.14.0",
+  "netease:structure_feature": {
+    "description": {
+      "identifier": "tutorial_demo:woodwell_structure_feature"
+    },
+    "places_structure": "tutorial_demo:woodwell"
+  }
+}
+```
+
+```json
+{
+  "format_version": "1.14.0",
+  "netease:structure_feature": {
+    "description": {
+      "identifier": "tutorial_demo:stonewell_structure_feature"
+    },
+    "places_structure": "tutorial_demo:stonewell"
+  }
+}
+```
+
+```json
+{
+  "format_version": "1.14.0",
+  "netease:structure_feature": {
+    "description": {
+      "identifier": "tutorial_demo:cobblestonewell_structure_feature"
+    },
+    "places_structure": "tutorial_demo:cobblestonewell"
+  }
+}
+```
+
+```json
+{
+  "format_version": "1.14.0",
+  "netease:structure_feature": {
+    "description": {
+      "identifier": "tutorial_demo:stonebrickswell_structure_feature"
+    },
+    "places_structure": "tutorial_demo:stonebrickswell"
+  }
+}
+```
+
+由于我们的结构位于`tutorial_demo`文件夹中，因此命名空间是`tutorial_demo`。我们将其挂接到`places_structure`中，即可实现结构特征的制作。
+
+## 使用加权随机特征分配水井权重
+
+我们新建`random_well_feature.json`文件：
+
+```json
+{
+  "format_version": "1.13.0",
+  "minecraft:weighted_random_feature": {
+    "description": {
+      "identifier": "tutorial_demo:random_well_feature"
+    },
+    "features": [
+      ["tutorial_demo:woodwell_structure_feature", 1],
+      ["tutorial_demo:stonewell_structure_feature", 1],
+      ["tutorial_demo:cobblestonewell_structure_feature", 1],
+      ["tutorial_demo:stonebrickswell_structure_feature", 1]
+    ]
+  }
+}
+```
+
+我们将所有水井的权重设置为1，这样每个水井都有$\frac{1}{1+1+1+1}=\frac{1}{4}$的概率生成。当选中的水井成功生成时该特征会判定成功，否则就会判定失败。
+
+## 挂接特征规则
+
+我们创建`overworld_well_structure_feature.json`文件，并写入如下：
+
+```json
+{
+  "format_version": "1.13.0",
+  "minecraft:feature_rules": {
+    "description": {
+      "identifier": "tutorial_demo:overworld_well_structure_feature",
+      "places_feature": "tutorial_demo:random_well_feature"
+    },
+    "conditions": {
+      "placement_pass": "surface_pass",
+      "minecraft:biome_filter": [
+        {
+          "any_of": [
+            {
+              "test": "has_biome_tag",
+              "operator": "==",
+              "value": "overworld"
+            },
+            {
+              "test": "has_biome_tag",
+              "operator": "==",
+              "value": "overworld_generation"
+            }
+          ]
+        }
+      ]
+    },
+    "distribution": {
+      "iterations": 1,
+      "x": {
+        "distribution": "uniform",
+        "extent": [
+          0,
+          16
+        ]
+      },
+      "y": "query.heightmap(variable.worldx, variable.worldz)-3",
+      "z": {
+        "distribution": "uniform",
+        "extent": [
+          0,
+          16
+        ]
+      },
+      "scatter_chance": 100
+    }
+  }
+}
+```
+
+![](./images/16.9_in-game_1.png)
+
+我们可以看到，水井特征如期生成了。
+
+![](./images/16.9_in-game_2.png)
+
+当然，虽然我们的特征规则设置为了每个区块放置一次加权随机特征，但是也是有几率出现这种三联水井的情况的。这代表我们的特征放置非常成功！