vault backup: 2024-10-12 17:19:45

03-UnrealEngine/Gameplay/UObject/UnrealSpecifiers/Meta/Niagara/NiagaraClearEachFrame.md

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+# NiagaraClearEachFrame
+
+- **功能描述：** ScriptStruct /Script/Niagara.NiagaraSpawnInfo
+- **使用位置：** USTRUCT
+- **引擎模块：** Niagara
+- **元数据类型：** bool
+- **常用程度：** 0
+
+指定某结构的数据在Niagara后续每一帧不应该读取，只作为初始数据。
+
+当前只用在FNiagaraSpawnInfo上，仅仅内部用。
+
+## 源码例子：
+
+```cpp
+/** Data controlling the spawning of particles */
+USTRUCT(BlueprintType, meta = (DisplayName = "Spawn Info", NiagaraClearEachFrame = "true"))
+struct FNiagaraSpawnInfo
+{
+}
+```
+
+## 原理：
+
+```cpp
+// If the NiagaraClearEachFrame value is set on the data set, we don't bother reading it in each frame as we know that it is is invalid. However,
+// this is only used for the base data set. Other reads are potentially from events and are therefore perfectly valid.
+if (DataSetIndex == 0 && Var.GetType().GetScriptStruct() != nullptr && Var.GetType().GetScriptStruct()->GetMetaData(TEXT("NiagaraClearEachFrame")).Equals(TEXT("true"), ESearchCase::IgnoreCase))
+{
+	Fmt = VariableName + TEXT("{0} = {4};\n");
+}
+```