UKismetMathLibrary::Matrix_GetFrustumBottomPlane

function Engine Blueprint Since 4.0

#include "Kismet/KismetMathLibrary.h"

Access: public Specifiers: staticBlueprintPure

Description

Extracts the bottom clipping plane from a view-projection matrix. Returns false if extraction fails.

Caveats & Gotchas

• The extracted plane's W component encodes the signed distance from the origin; comparing it directly against another plane's W without normalizing gives meaningless results.
• For oblique projection matrices (used in planar reflections) the standard Gribb-Hartmann extraction can be incorrect — verify results when using non-standard projections.

Signature

static UE_INL_API bool Matrix_GetFrustumBottomPlane(const FMatrix& M, FPlane& OutPlane)

Parameters

Name	Type	Description	Default
M	const FMatrix&	The view-projection matrix to extract the bottom frustum plane from.	—
OutPlane	FPlane&	The extracted bottom plane of the frustum.	—

Return Type

bool

Example

Test visibility against all six frustum planes C++

FPlane Planes[6];
bool bValid =
    UKismetMathLibrary::Matrix_GetFrustumNearPlane(VP, Planes[0]) &&
    UKismetMathLibrary::Matrix_GetFrustumFarPlane(VP, Planes[1]) &&
    UKismetMathLibrary::Matrix_GetFrustumLeftPlane(VP, Planes[2]) &&
    UKismetMathLibrary::Matrix_GetFrustumRightPlane(VP, Planes[3]) &&
    UKismetMathLibrary::Matrix_GetFrustumTopPlane(VP, Planes[4]) &&
    UKismetMathLibrary::Matrix_GetFrustumBottomPlane(VP, Planes[5]);
if (bValid)
{
    bool bInFrustum = true;
    for (const FPlane& Plane : Planes)
        bInFrustum &= Plane.PlaneDot(TestPoint) >= 0.0f;
}

Version History

Introduced in: 4.0

Version	Status	Notes
5.6	stable	—

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