Struct MeshInstanceDesc

Parameters used to configure the creation of instances that are part of a IRayTracingAccelStruct.

Inherited Members
Namespace: UnityEngine.Rendering.UnifiedRayTracing
Assembly: Unity.UnifiedRayTracing.Runtime.dll
Syntax
public struct MeshInstanceDesc

Constructors

MeshInstanceDesc(Mesh, int)

Creates a MeshInstanceDesc.

Declaration
public MeshInstanceDesc(Mesh mesh, int subMeshIndex = 0)
Parameters
Type Name Description
Mesh mesh

The Mesh used to build this instance's geometry.
int subMeshIndex

The index of the sub-mesh (MeshInstanceDesc references a single sub-mesh).

Fields

enableTriangleCulling

Whether front/back face culling for this ray tracing instance is enabled. Default value: true.

Declaration
public bool enableTriangleCulling
Field Value
Type Description
bool

frontTriangleCounterClockwise

Whether to flip the way triangles face in this ray tracing instance. Default value: false.

Declaration
public bool frontTriangleCounterClockwise
Field Value
Type Description
bool

instanceID

Instance identifier. Can be accessed in the HLSL via the instanceID member of Hit (Hit is returned by the TraceRayClosestHit/TraceRayAnyHit HLSL functions).

Declaration
public uint instanceID
Field Value
Type Description
uint

localToWorldMatrix

The transformation matrix of the instance.

Declaration
public Matrix4x4 localToWorldMatrix
Field Value
Type Description
Matrix4x4

mask

The instance mask.

Declaration
public uint mask
Field Value
Type Description
uint
Remarks

Instances in the acceleration structure contain an 8-bit user defined instance mask. The TraceRayClosestHit/TraceRayAnyHit HLSL functions have an 8-bit input parameter, InstanceInclusionMask which gets ANDed with the instance mask from any instance that is a candidate for intersection during acceleration structure traversal on the GPU. If the result of the AND operation is zero, the GPU ignores the intersection.

mesh

The Mesh used to build this instance's geometry.

Declaration
public Mesh mesh
Field Value
Type Description
Mesh

opaqueGeometry

Whether the geometry is considered opaque. Default value: true.

Declaration
public bool opaqueGeometry
Field Value
Type Description
bool
Remarks

When an instance's opaqueGeometry field is set to false, the AnyHitExecute shader function will be invoked during the ray traversal when a hit is found. This alows the user to programmatically decide whether to reject or accept the candidate hit. This feature can, for example, be used to implement alpha cutout transparency. For best performance, prefer to set this parameter to false for as many geometries as possibe.

subMeshIndex

The index of the sub-mesh (MeshInstanceDesc references a single sub-mesh).

Declaration
public int subMeshIndex
Field Value
Type Description
int

Extension Methods