FMath::SegmentIntersection2D
#include "Math/UnrealMathUtility.h"
Access: public
Specifiers: static
Description
Tests whether two 3D segments intersect when projected onto the XY plane and returns the intersection point. Ignores the Z component for the intersection test itself.
Caveats & Gotchas
- • The intersection test is performed in 2D (XY plane only). Two segments that miss each other in XY will return false even if they cross in 3D space. Verify this matches your use case.
- • The Z value of out_IntersectionPoint is computed by linearly interpolating along segment A at the parametric intersection T — it does not represent a 3D intersection height.
- • Parallel or collinear segments always return false regardless of overlap.
Signature
static CORE_API bool SegmentIntersection2D(const FVector& SegmentStartA, const FVector& SegmentEndA, const FVector& SegmentStartB, const FVector& SegmentEndB, FVector& out_IntersectionPoint)Parameters
| Name | Type | Description | Default |
|---|---|---|---|
| SegmentStartA | const FVector& | Start of the first segment. | — |
| SegmentEndA | const FVector& | End of the first segment. | — |
| SegmentStartB | const FVector& | Start of the second segment. | — |
| SegmentEndB | const FVector& | End of the second segment. | — |
| out_IntersectionPoint | FVector& | Receives the 2D intersection point (Z will be interpolated) if the function returns true. | — |
Return Type
bool Example
Detect crossing of two navmesh boundary edges on the ground plane C++
FVector CrossPt;
if (FMath::SegmentIntersection2D(EdgeA_Start, EdgeA_End, EdgeB_Start, EdgeB_End, CrossPt))
{
// CrossPt.XY is the intersection on the ground plane
DrawDebugPoint(GetWorld(), CrossPt, 8.f, FColor::Red);
}Tags
Version History
Introduced in: 4.0
| Version | Status | Notes |
|---|---|---|
| 5.6 | stable | — |
Feedback
Was this helpful?