Updates the instance ID of a ray tracing instance associated with the Renderer passed as argument.
Ray tracing instances in the acceleration structure contain an user-defined instance ID. This instance ID can be accessed in HLSL using InstanceID() intrinsic and provides a way to access additional per-instance custom data. Note that this function is available only in closest hit, any hit, and intersection shaders.
By default, if an instance ID is not specified when calling RayTracingAccelerationStructure.AddInstance function, Unity will assign a instance ID lower than the value returned by the RayTracingAccelerationStructure.GetInstanceCount function.
Note that building the acceleration structure on the GPU has to be triggered by calling RayTracingAccelerationStructure.Build or CommandBuffer.BuildRayTracingAccelerationStructure.
Additional resources: RayTracingAccelerationStructure.RemoveInstance.