Surfaces

autocad_entity: autocad_surface

Features with this value are used to store several AutoCAD entities including face, polygon mesh, polyface mesh, or surface entities. Extruded, planar, revolved, lofted, and swept surfaces are represented as autocad_surface, which may contain multiple unconnected surfaces, each of which is composed of faces, which may or may not be planar. This value is used by both the reader and the writer.

Region entities may also be read as surfaces, if the reader parameter Read Region Entities as Areas is disabled (set to No). If regions are read as areas, their autocad_entity value is autocad_region instead of autocad_surface.

Surfaces support appearances, but only one appearance per surface. For two-sided surfaces, the writer will split the surface into one surface per side. Furthermore, only subdivision mesh entities support textured appearances. Subdivision meshes will preferentially be written from surfaces with textured appearances. (Textured appearances are only supported by RealDWG.)

For writing, all 3D surface geometry types are supported. Any types of 3D geometry which are not directly supported as entities are decomposed into triangulated mesh representation prior to writing.

Attribute Name	Content
autocad_subdmesh_base_faces (used only by the reader)	Indicates the number of faces in a subdivision mesh at the base smoothness level of 0. Range: 32-bit integer value Default: No default
autocad_subdmesh_base_vertices (used only by the reader)	Indicates the number of vertices in a subdivision mesh at the base smoothness level of 0. Range: 32-bit integer value Default: No default
autocad_subdmesh_smooth_level (used only by the reader)	Indicates the smoothness level of a subdivision mesh. A value of 0 represents the base smoothness of the mesh geometry and higher values indicate greater subdivisions which increase smoothness. Range: 0-4 Default: 0
autocad_subdmesh_smoothed_faces (used only by the reader)	Indicates the number of faces in a subdivision mesh at the current smoothness level. Range: 32-bit integer value Default: No default
autocad_subdmesh_smoothed_vertices (used only by the reader)	Indicates the number of vertices in a subdivision mesh at the current smoothness level. Range: 32-bit integer value Default: No default
autocad_subdmesh_watertight (used only by the reader)	Indicates whether a subdivision mesh is watertight, based on adjacent polygons sharing common vertices. Range: Yes \| No Default: No default

Attribute Name

Content

autocad_subdmesh_base_faces

(used only by the reader)

Indicates the number of faces in a subdivision mesh at the base smoothness level of 0.

Range: 32-bit integer value

Default: No default

autocad_subdmesh_base_vertices

(used only by the reader)

Indicates the number of vertices in a subdivision mesh at the base smoothness level of 0.

Range: 32-bit integer value

Default: No default

autocad_subdmesh_smooth_level

(used only by the reader)

Indicates the smoothness level of a subdivision mesh. A value of 0 represents the base smoothness of the mesh geometry and higher values indicate greater subdivisions which increase smoothness.

Range: 0-4

Default: 0

autocad_subdmesh_smoothed_faces

(used only by the reader)

Indicates the number of faces in a subdivision mesh at the current smoothness level.

Range: 32-bit integer value

Default: No default

autocad_subdmesh_smoothed_vertices

(used only by the reader)

Indicates the number of vertices in a subdivision mesh at the current smoothness level.

Range: 32-bit integer value

Default: No default

autocad_subdmesh_watertight

(used only by the reader)

Indicates whether a subdivision mesh is watertight, based on adjacent polygons sharing common vertices.

Range: Yes | No

Default: No default