Edit

Share via

Direct3D 12 raytracing HLSL system value intrinsics

  • Article

System values are retrieved by using special intrinsic functions, rather than including parameters with special semantics in your shader function signature.

In this section

Ray dispatch system values

Topic Description
DispatchRaysIndex Gets the current x and y location within the width and height obtained with the DispatchRaysDimensions system value intrinsic.
DispatchRaysDimensions The width, height and depth values from the D3D12_DISPATCH_RAYS_DESC structure specified in the originating DispatchRays call.

Ray system values

Topic Description
WorldRayOrigin The world-space origin of the current ray.
WorldRayDirection The world-space direction for the current ray.
RayTMin A float representing the current parametric starting point for the ray.
RayTCurrent A float representing the current parametric ending point for the ray.
RayFlags An unsigned integer containing the current ray_flag flags.

Primitive/object space system values

Topic Description
InstanceIndex The autogenerated index of the current instance in the top-level raytracing acceleration structure.
InstanceID The user-provided identifier for the instance on the bottom-level acceleration structure instance within the top-level structure.
PrimitiveIndex The autogenerated index of the primitive within the geometry inside the bottom-level acceleration structure instance.
ObjectRayOrigin The object-space origin for the current ray.
ObjectRayDirection The object-space direction for the current ray.
ObjectToWorld3x4 A matrix for transforming from object-space to world-space.
ObjectToWorld4x3 A matrix for transforming from object-space to world-space.
WorldToObject3x4 A matrix for transforming from world-space to object-space
WorldToObject4x3 A matrix for transforming from world-space to object-space

Hit-specific system values

Topic Description
HitKind Returns the value passed as the HitKind parameter to ReportHit.