Unreal engine 4 C ++ is used to draw functions for debugging.

Unreal engine 4 C ++ is used to draw functions for debugging.

UE4 provides many predefined debugging and rendering functions, which are convenient during debugging. You can draw points, lines, circles, balls, arrows, cubes, capsules, and even splines, strings, and grids in a scenario. What's better is that you can control the line thickness, Which is intuitive during debugging.

To use these functions, you only need to include the DrawDebugHelpers. h header file. The following describes several major plotting functions:

1. Draw points

ENGINE_API void DrawDebugPoint(const UWorld* InWorld, FVector const& Position, float Size, FColor const& PointColor, bool bPersistentLines = false, float LifeTime=-1.f, uint8 DepthPriority = 0);

In the optional parameters, we can control the size, color, duration, and so on. BPersistentLines indicates whether the entire drawn object is a persistent object. If it is set to true, the current World will be displayed until you call the following method to release it:

 void FlushPersistentDebugLines(const UWorld* InWorld);

For other plotting functions, this parameter has the same meaning.
2. Draw a line

ENGINE_API void DrawDebugLine(const UWorld* InWorld, FVector const& LineStart, FVector const& LineEnd, FColor const& Color, bool bPersistentLines = false, float LifeTime=-1.f, uint8 DepthPriority = 0, float Thickness = 0.f);

Note the Thickness parameter, which controls the Thickness of the line.
3. Draw arrows

ENGINE_API void DrawDebugDirectionalArrow(const UWorld* InWorld, FVector const& LineStart, FVector const& LineEnd, float ArrowSize, FColor const& Color, bool bPersistentLines = false, float LifeTime=-1.f, uint8 DepthPriority = 0);

This function draws a directed arrow, which is similar to the draw line. ArrowSize is the size of the arrow.
4. Draw a Box

ENGINE_API void DrawDebugBox(const UWorld* InWorld, FVector const& Center, FVector const& Extent, FColor const& Color, bool bPersistentLines = false, float LifeTime=-1.f, uint8 DepthPriority = 0);/** Draw a debug box with rotation */ENGINE_API void DrawDebugBox(const UWorld* InWorld, FVector const& Center, FVector const& Box, const FQuat & Rotation, FColor const& Color, bool bPersistentLines = false, float LifeTime=-1.f, uint8 DepthPriority = 0);

The first one is drawn based on the Box size, and the second one can be drawn based on a certain degree of rotation.
5. Draw a sphere

ENGINE_API void DrawDebugSphere(const UWorld* InWorld, FVector const& Center, float Radius, int32 Segments, FColor const& Color, bool bPersistentLines = false, float LifeTime=-1.f, uint8 DepthPriority = 0);

Segments controls the Segments of the sphere. The larger the Segments, the finer the Segments.
6. There are many other less commonly used ones, such as 2D circles, cylinders, vertebral bodies, flat headers, and capsules. This is only shown here. For details, see DrawDebugHelpers. h.

ENGINE_API void DrawDebugCoordinateSystem(const UWorld* InWorld, FVector const& AxisLoc, FRotator const& AxisRot, float Scale, bool bPersistentLines = false, float LifeTime=-1.f, uint8 DepthPriority = 0);/** Draw Debug Circle */ENGINE_API void DrawDebugCircle(const UWorld* InWorld, const FMatrix& TransformMatrix, float Radius, int32 Segments, const FColor& Color, bool bPersistentLines = false, float LifeTime=-1.f, uint8 DepthPriority = 0);/** Draw Debug 2D donut */ENGINE_API void DrawDebug2DDonut(const UWorld* InWorld, const FMatrix& TransformMatrix, float InnerRadius, float OuterRadius, int32 Segments, const FColor& Color, bool bPersistentLines = false, float LifeTime=-1.f, uint8 DepthPriority = 0);/** Draw a debug sphere */ENGINE_API void DrawDebugSphere(const UWorld* InWorld, FVector const& Center, float Radius, int32 Segments, FColor const& Color, bool bPersistentLines = false, float LifeTime=-1.f, uint8 DepthPriority = 0);/** Draw a debug cylinder */ENGINE_API void DrawDebugCylinder(const UWorld* InWorld, FVector const& Start, FVector const& End, float Radius, int32 Segments, FColor const& Color, bool bPersistentLines = false, float LifeTime=-1.f, uint8 DepthPriority = 0);ENGINE_API void DrawDebugCone(const UWorld* InWorld, FVector const& Origin, FVector const& Direction, float Length, float AngleWidth, float AngleHeight, int32 NumSides, FColor const& Color, bool bPersistentLines=false, float LifeTime=-1.f, uint8 DepthPriority = 0);/** Used by gameplay when defining a cone by a vertical and horizontal dot products. */ENGINE_API void DrawDebugAltCone(const UWorld* InWorld, FVector const& Origin, FRotator const& Rotation, float Length, float AngleWidth, float AngleHeight, FColor const& DrawColor, bool bPersistentLines=false, float LifeTime=-1.f, uint8 DepthPriority=0);ENGINE_API void DrawDebugString(const UWorld* InWorld, FVector const& TextLocation, const FString& Text, class AActor* TestBaseActor = NULL, FColor const& TextColor = FColor::White, float Duration = -1.000000);ENGINE_API void DrawDebugFrustum(const UWorld* InWorld, const FMatrix& FrustumToWorld, FColor const& Color, bool bPersistentLines = false, float LifeTime=-1.f, uint8 DepthPriority = 0);/** Draw a capsule using the LineBatcher */ENGINE_API void DrawDebugCapsule(const UWorld* InWorld, FVector const& Center, float HalfHeight, float Radius, const FQuat & Rotation, FColor const& Color, bool bPersistentLines=false, float LifeTime=-1.f, uint8 DepthPriority = 0);/** Draw a debug camera shape.  FOV is full angle in degrees. */ENGINE_API void DrawDebugCamera(const UWorld* InWorld, FVector const& Location, FRotator const& Rotation, float FOVDeg, float Scale=1.f, FColor const& Color=FColor::White, bool bPersistentLines=false, float LifeTime=-1.f, uint8 DepthPriority = 0);ENGINE_API void FlushDebugStrings(const UWorld* InWorld);ENGINE_API void DrawDebugSolidBox(const UWorld* InWorld, FVector const& Center, FVector const& Box, FColor const& Color, bool bPersistent=false, float LifeTime=-1.f, uint8 DepthPriority = 0);ENGINE_API void DrawDebugSolidBox(const UWorld* InWorld, FVector const& Center, FVector const& Extent, FQuat const& Rotation, FColor const& Color, bool bPersistent=false, float LifeTime=-1.f, uint8 DepthPriority = 0);ENGINE_API void DrawDebugMesh(const UWorld* InWorld, TArray<FVector> const& Verts, TArray<int32> const& Indices, FColor const& Color, bool bPersistent=false, float LifeTime=-1.f, uint8 DepthPriority = 0);ENGINE_API void DrawDebugSolidPlane(const UWorld* InWorld, FPlane const& P, FVector const& Loc, float Size, FColor const& Color, bool bPersistent=false, float LifeTime=-1, uint8 DepthPriority = 0);/* Draws a 2D Histogram of size 'DrawSize' based FDebugFloatHistory struct, using DrawTransform for the position in the world. */ENGINE_API void DrawDebugFloatHistory(UWorld const & WorldRef, FDebugFloatHistory const & FloatHistory, FTransform const & DrawTransform, FVector2D const & DrawSize, FColor const & DrawColor, bool const & bPersistent = false, float const & LifeTime = -1.f, uint8 const & DepthPriority = 0);/* Draws a 2D Histogram of size 'DrawSize' based FDebugFloatHistory struct, using DrawLocation for the location in the world, rotation will face camera of first player. */ENGINE_API void DrawDebugFloatHistory(UWorld const & WorldRef, FDebugFloatHistory const & FloatHistory, FVector const & DrawLocation, FVector2D const & DrawSize, FColor const & DrawColor, bool const & bPersistent = false, float const & LifeTime = -1.f, uint8 const & DepthPriority = 0);