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D3D12_RAYTRACING_INSTANCE_FLAGS enumeration (d3d12.h)

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Flags for a raytracing acceleration structure instance. These flags can be used to override D3D12_RAYTRACING_GEOMETRY_FLAGS for individual instances.

Syntax

typedef enum D3D12_RAYTRACING_INSTANCE_FLAGS {
  D3D12_RAYTRACING_INSTANCE_FLAG_NONE = 0,
  D3D12_RAYTRACING_INSTANCE_FLAG_TRIANGLE_CULL_DISABLE = 0x1,
  D3D12_RAYTRACING_INSTANCE_FLAG_TRIANGLE_FRONT_COUNTERCLOCKWISE = 0x2,
  D3D12_RAYTRACING_INSTANCE_FLAG_FORCE_OPAQUE = 0x4,
  D3D12_RAYTRACING_INSTANCE_FLAG_FORCE_NON_OPAQUE = 0x8
} ;

Constants

 
D3D12_RAYTRACING_INSTANCE_FLAG_NONE
Value: 0
No options specified.
D3D12_RAYTRACING_INSTANCE_FLAG_TRIANGLE_CULL_DISABLE
Value: 0x1
Disables front/back face culling for this instance. The Ray flags RAY_FLAG_CULL_BACK_FACING_TRIANGLES and RAY_FLAG_CULL_FRONT_FACING_TRIANGLES will have no effect on this instance.
D3D12_RAYTRACING_INSTANCE_FLAG_TRIANGLE_FRONT_COUNTERCLOCKWISE
Value: 0x2
This flag reverses front and back facings, which is useful if the application’s natural winding order differs from the default. By default, a triangle is front facing if its vertices appear clockwise from the ray origin and back facing if its vertices appear counter-clockwise from the ray origin, in object space in a left-handed coordinate system.

Since these winding direction rules are defined in object space, they are unaffected by instance transforms. For example, an instance transform matrix with negative determinant (e.g. mirroring some geometry) does not change the facing of the triangles within the instance. Per-geometry transforms defined in D3D12_RAYTRACING_GEOMETRY_TRIANGLES_DESC , by contrast, get combined with the associated vertex data in object space, so a negative determinant matrix there does flip triangle winding.
D3D12_RAYTRACING_INSTANCE_FLAG_FORCE_OPAQUE
Value: 0x4
The instance will act as if D3D12_RAYTRACING_GEOMETRY_FLAG_OPAQUE had been specified for all the geometries in the bottom-level acceleration structure referenced by the instance. Note that this behavior can be overridden by the ray flag RAY_FLAG_FORCE_NON_OPAQUE.

This flag is mutually exclusive to the D3D12_RAYTRACING_INSTANCE_FLAG_FORCE_NON_OPAQUE flag.
D3D12_RAYTRACING_INSTANCE_FLAG_FORCE_NON_OPAQUE
Value: 0x8
The instance will act as if D3D12_RAYTRACING_GEOMETRY_FLAG_OPAQUE had not been specified for any of the geometries in the bottom-level acceleration structure referenced by the instance. Note that this behavior can be overridden by the ray flag RAY_FLAG_FORCE_OPAQUE.

This flag is mutually exclusive to the D3D12_RAYTRACING_INSTANCE_FLAG_FORCE_OPAQUE flag.

Requirements

Requirement Value
Header d3d12.h