DirectionalArrowComponent

The DirectionalArrowComponent provides visual directional feedback during object placement in the Grid Placement System. It displays a 3D arrow that indicates the "front" or orientation direction of placeable objects, helping users understand how objects will be oriented when placed.

Overview

This component uses a hierarchical structure where the SceneComponent acts as a rotatable pivot, and a child StaticMeshComponent displays the actual arrow mesh. This design allows for flexible positioning and rotation of the directional indicator without affecting the parent object.

Component Architecture

DirectionalArrowComponent (SceneComponent)
└── ArrowMeshComponent (StaticMeshComponent)
    ├── Arrow Mesh Asset
    ├── Dynamic Material
    └── Collision: Disabled

Key Features

• ✅ Hierarchical Design - SceneComponent pivot with mesh child for flexible control
• ✅ Multiple Directions - Forward, Backward, Left, Right, or Custom angle
• ✅ Dynamic Materials - Runtime color and visibility changes
• ✅ Placement Integration - Seamlessly works with Grid Placement System
• ✅ Performance Optimized - Only visible during placement mode

Setup

Adding to Your Placeable Objects

1. Add Component to Blueprint:
   • Open your placeable object Blueprint
   • Add DirectionalArrowComponent as a component
   • Position it as a child of your root component

2. Implement PlaceableObjectInterface:

// In your placeable object Blueprint or C++ class
UFUNCTION(BlueprintNativeEvent, BlueprintCallable, Category = "Direction")
UDirectionalArrowComponent* GetArrowComponent() const;
   
// Implementation should return your DirectionalArrowComponent

3. Configure Direction Settings:
   • Set Arrow Direction to match your object's "front"
   • Adjust Arrow Distance From Center for proper positioning
   • Fine-tune Arrow Scale for visibility

Configuration Properties

Arrow Settings

Arrow Mesh

Arrow Direction Options

EArrowDirection Enum

Direction Examples

// For a chair (seat faces forward)
ArrowDirection = EArrowDirection::Forward
 
// For a wall-mounted TV (screen faces outward from wall)
ArrowDirection = EArrowDirection::Forward
 
// For a desk lamp (light cone direction)
ArrowDirection = EArrowDirection::Forward
 
// For an object with 45-degree angle requirement
ArrowDirection = EArrowDirection::Custom
CustomDirectionAngle = 45.0f

Blueprint API

Visibility Control

SetArrowVisibility

UFUNCTION(BlueprintCallable, Category = "Arrow")
void SetArrowVisibility(bool bNewVisible);

Controls arrow visibility.

Parameters:

• bNewVisible - true to show arrow, false to hide

IsArrowVisible

UFUNCTION(BlueprintPure, Category = "Arrow")
bool IsArrowVisible() const;

Returns current arrow visibility state.

HideArrowCompletely

void HideArrowCompletely();

Completely hides the arrow and clears all materials.

ShowArrowWithMaterial

void ShowArrowWithMaterial(UMaterialInstanceDynamic* MaterialInstance);

Shows the arrow with a specific dynamic material instance.

Material Management

SetArrowMaterial

UFUNCTION(BlueprintCallable, Category = "Arrow")
void SetArrowMaterial(UMaterialInstanceDynamic* MaterialInstance);

Applies a dynamic material instance to the arrow.

Parameters:

• MaterialInstance - Dynamic material to apply (usually from placement system)

ClearArrowMaterial

UFUNCTION(BlueprintCallable, Category = "Arrow")
void ClearArrowMaterial();

Removes the current material and hides the arrow.

SetArrowColor

UFUNCTION(BlueprintCallable, Category = "Arrow")
void SetArrowColor(const FLinearColor& Color);

Sets the arrow color by creating a dynamic material instance.

Parameters:

• Color - Linear color for the arrow

Direction and Positioning

SetArrowDirection

UFUNCTION(BlueprintCallable, Category = "Arrow")
void SetArrowDirection(EArrowDirection Direction);

Changes the arrow direction at runtime.

SetArrowDistanceFromOverlay

UFUNCTION(BlueprintCallable, Category = "Arrow")
void SetArrowDistanceFromOverlay(float OverlayWidth, float OverlayHeight, float ExtraMargin = 10.0f);

Automatically calculates arrow distance based on overlay size.

Parameters:

• OverlayWidth - Width of the placement overlay
• OverlayHeight - Height of the placement overlay
• ExtraMargin - Additional spacing beyond overlay bounds

Pivot Control

SetArrowPivotRotation

UFUNCTION(BlueprintCallable, Category = "Arrow")
void SetArrowPivotRotation(const FRotator& Rotation);

Rotates the entire arrow pivot (affects final arrow position).

GetArrowPivotRotation

UFUNCTION(BlueprintPure, Category = "Arrow")
FRotator GetArrowPivotRotation() const;

Returns the current pivot rotation.

Integration with Placement System

Automatic Management

The DirectionalArrowComponent is automatically managed by the Grid Placement System:

1. During Placement Preview:
   • Arrow appears with placement overlay color
   • Updates in real-time with validity changes
   • Synchronizes with overlay material

2. During Object Editing:
   • Arrow shows for selected objects
   • Indicates current object orientation
   • Updates with rotation changes

3. Normal Gameplay:
   • Arrow is completely hidden
   • No performance impact
   • Materials are cleared

Material Synchronization

The arrow automatically synchronizes with the placement system's overlay material:

// Placement System automatically calls this
void ObjectManager::UpdateArrowMaterial()
{
    if (CurrentArrowComponent && OverlayDynamicMaterial)
    {
        CurrentArrowComponent->ShowArrowWithMaterial(OverlayDynamicMaterial);
    }
}

Color States

Performance Considerations

Optimization Features

1. Conditional Visibility:

   • Arrows only visible during placement/editing
   • Automatically hidden during normal gameplay
   • No draw calls when hidden

2. Material Management:

   • Dynamic materials created only when needed
   • Materials cleared when not in use
   • Shared material instances when possible

3. Component Lifecycle:

   • Components activate only during placement
   • Minimal memory footprint when inactive
   • Efficient mesh asset loading

Troubleshooting

Common Issues

"Arrow not showing during placement"

• Verify GetArrowComponent() is implemented and returns valid component
• Check that ArrowDistanceFromCenter isn't too small/large
• Ensure object implements IPlaceableObjectInterface

"Arrow pointing wrong direction"

• Rotate Arrow Manually
• Check ArrowDirection setting matches object's intended front
• For custom angles, verify CustomDirectionAngle value
• Test with different EArrowDirection values

"Arrow too small/large"

• Adjust ArrowScale property (1.0 = normal size)
• Check ArrowDistanceFromCenter for positioning
• Verify arrow mesh is loaded correctly

"Arrow appears in wrong position"

• Ensure component is attached to correct parent
• Check ArrowHeightOffset for surface clearance

Integration Workflow

1. Component Setup → Add to placeable object Blueprint
2. Direction Configuration → Set appropriate arrow direction
3. Interface Implementation → Return component in GetArrowComponent()
4. Fine-tuning → Adjust distance, scale, and positioning
5. Testing → Verify arrow appears during placement

The DirectionalArrowComponent provides essential visual feedback for object orientation, making the placement experience more intuitive and professional for your users.