# TraceQuery

- **功能描述：** Enum /Script/Engine.ECollisionChannel
- **使用位置：** UENUM::UMETA
- **引擎模块：** Enum Property
- **元数据类型：** bool
- **常用程度：** 0

只在ECollisionChannel 上使用，指定哪些通道是用来Trace的。

## 源码例子：

```cpp
UENUM(BlueprintType)
enum ECollisionChannel : int
{

	ECC_WorldStatic UMETA(DisplayName="WorldStatic"),
	ECC_WorldDynamic UMETA(DisplayName="WorldDynamic"),
	ECC_Pawn UMETA(DisplayName="Pawn"),
	ECC_Visibility UMETA(DisplayName="Visibility" , TraceQuery="1"),
	ECC_Camera UMETA(DisplayName="Camera" , TraceQuery="1"),
	ECC_PhysicsBody UMETA(DisplayName="PhysicsBody"),
	ECC_Vehicle UMETA(DisplayName="Vehicle"),
	ECC_Destructible UMETA(DisplayName="Destructible"),

	/** Reserved for gizmo collision */
	ECC_EngineTraceChannel1 UMETA(Hidden),

	ECC_EngineTraceChannel2 UMETA(Hidden),
	ECC_EngineTraceChannel3 UMETA(Hidden),
	ECC_EngineTraceChannel4 UMETA(Hidden), 
	ECC_EngineTraceChannel5 UMETA(Hidden),
	ECC_EngineTraceChannel6 UMETA(Hidden),

	ECC_GameTraceChannel1 UMETA(Hidden),
	ECC_GameTraceChannel2 UMETA(Hidden),
	ECC_GameTraceChannel3 UMETA(Hidden),
	ECC_GameTraceChannel4 UMETA(Hidden),
	ECC_GameTraceChannel5 UMETA(Hidden),
	ECC_GameTraceChannel6 UMETA(Hidden),
	ECC_GameTraceChannel7 UMETA(Hidden),
	ECC_GameTraceChannel8 UMETA(Hidden),
	ECC_GameTraceChannel9 UMETA(Hidden),
	ECC_GameTraceChannel10 UMETA(Hidden),
	ECC_GameTraceChannel11 UMETA(Hidden),
	ECC_GameTraceChannel12 UMETA(Hidden),
	ECC_GameTraceChannel13 UMETA(Hidden),
	ECC_GameTraceChannel14 UMETA(Hidden),
	ECC_GameTraceChannel15 UMETA(Hidden),
	ECC_GameTraceChannel16 UMETA(Hidden),
	ECC_GameTraceChannel17 UMETA(Hidden),
	ECC_GameTraceChannel18 UMETA(Hidden),
	
	/** Add new serializeable channels above here (i.e. entries that exist in FCollisionResponseContainer) */
	/** Add only nonserialized/transient flags below */

	// NOTE!!!! THESE ARE BEING DEPRECATED BUT STILL THERE FOR BLUEPRINT. PLEASE DO NOT USE THEM IN CODE

	ECC_OverlapAll_Deprecated UMETA(Hidden),
	ECC_MAX,
};
```

## 原理：

```cpp
void UCollisionProfile::LoadProfileConfig(bool bForceInit)
{
		static const FString TraceType = TEXT("TraceQuery");
}
```