Sweeping Socket Trace Target

The BP_SweepingSocketTraceTarget class in the Collision Manager system is a Blueprint class derived from BP_TraceTarget, designed to handle precise collision tracing for sweeping melee attacks, such as weapon swings or fist strikes, in Action RPGs. It enables developers to create accurate hit detection by tracing along a mesh’s sockets, ensuring collisions align with attack animations. This class addresses the need for realistic, mesh-based collision detection, integrating with the BP_CollisionComponent to support dynamic combat mechanics.

Basic Usage

The BP_SweepingSocketTraceTarget is used by adding it to a BP_CollisionComponent, setting a mesh and sockets, and activating it via animations or abilities. Below are the primary functions for interacting with it in Blueprints.

1. ActivateCollision:

   • Purpose: Starts the tick-based collision trace along the specified mesh sockets.
   • Usage: Call via ActivateCollisionByTag on BP_CollisionComponent, often triggered by ANS_CollisionTrace.

2. DeactivateCollision:

   • Purpose: Stops the collision trace and cleans up.
   • Usage: Call via DeactivateCollisionByTag or automatically via ANS_CollisionTrace when the animation ends.

3. CollisionTrace:

   • Purpose: Performs the tick-based trace along the mesh’s socket paths to detect hits.
   • Usage: Override in a child Blueprint to customize trace behavior (e.g., adjust trace shape or path).

4. OnHit:

   • Purpose: Executes logic when the trace hits a valid target.
   • Usage: Override to apply Gameplay Effects or trigger events on hit.

5. SetCollisionProperties:

   • Purpose: Configures the mesh and sockets for tracing.
   • Usage: Call after adding the target type to set the weapon mesh and socket names.

Key Properties

Property Name	Purpose
Collision Radius	Defines the radius of the trace (e.g., for sphere or capsule traces); adjusts hit detection size.
Collision Object Types	Specifies object types the trace can collide with (e.g., Pawn, WorldStatic).
Collision Profile Names to Ignore	Ignores hits from actors with these collision profile names.
Gameplay Tags to Ignore	Ignores hits from actors with any of these Gameplay Tags.
Actor Classes to Ignore	Ignores hits from actors of these classes.
Draw Debug Type	Sets debug visibility for the trace (e.g., For One Frame, Persistent); used for testing.

Key Concepts

Mesh-Based Socket Tracing

The BP_SweepingSocketTraceTarget traces collisions along paths defined by a mesh’s sockets (e.g., blade start to end), ensuring hit detection matches the weapon’s visual motion. This is ideal for melee attacks requiring precise, animation-driven hit boxes.

• Purpose: Aligns collision detection with weapon mesh animations for realistic combat.
• Usage: Set the mesh and sockets via SetCollisionProperties and activate via ANS_CollisionTrace.
• Benefit: Enhances visual fidelity and hit accuracy for melee attacks.

Animation-Driven Collision

The class integrates with ANS_CollisionTrace to activate/deactivate traces during specific animation frames, ensuring collisions occur only when the attack visually connects. This ties hit detection to animation timing.

• Purpose: Synchronizes hit boxes with attack animations.
• Usage: Use ANS_CollisionTrace in animations with the correct Collision Target Tag.
• Benefit: Improves gameplay feel by matching collision to visual cues.

Customizable Hit Responses

The OnHit event allows developers to define custom responses to hits, such as applying Gameplay Effects or spawning Gameplay Cues. This flexibility supports varied combat mechanics, like different damage types or status effects.

• Purpose: Enables tailored hit reactions for specific weapons or abilities.
• Usage: Override OnHit in a child Blueprint to implement custom logic.
• Benefit: Supports diverse combat interactions with minimal setup.

Best Practices

• Workflows:
  • Use BP_SweepingSocketTraceTarget for melee weapons with skeletal meshes, reserving BP_TraceTarget for non-mesh-based traces.
  • Define clear socket names (e.g., BladeStart, BladeEnd) in the mesh to simplify SetCollisionProperties setup.
  • Test with ANS_CollisionTrace and debug visuals (Draw Debug Type) to ensure traces align with animations.
• Pitfalls to Avoid:
  • Always call SetCollisionProperties with valid mesh and sockets; missing sockets cause trace failures.
  • Don’t leave traces active beyond their intended duration; use DeactivateCollisionByTag or ANS_CollisionTrace to stop them.
  • Avoid excessive socket counts in SetCollisionProperties to prevent performance overhead.
• Performance Considerations:
  • Minimize active BP_SweepingSocketTraceTarget instances by deactivating unused traces promptly.
  • Use Collision Profile Names to Ignore and Gameplay Tags to Ignore to filter irrelevant hits.
  • Set Draw Debug Type to None in production to eliminate debug rendering costs.