DXHitTestOptionsGetOnlyFrontFacingTriangles Property

When true then only triangles that have normals (calculated from triangle positions) oriented in the opposite direction as the ray are returned (because ray is usually created from the camera's position this returns only triangles that are facing the camera). When false (by default), all hit triangles are returned regardless of their orientation.

public bool GetOnlyFrontFacingTriangles { get; set; }