unknown Object

src/ACadSharp/Entities/UnknownEntity.cs

@@ -4,10 +4,10 @@
 namespace ACadSharp.Entities
 {
 	/// <summary>
-	/// Class that holds the basic information for an unknown entity
+	/// Class that holds the basic information for an unknown <see cref="Entity"/>.
 	/// </summary>
 	/// <remarks>
-	/// Unknown entities may appear in the <see cref="CadDocument"/> if the dwg file contains proxies or entities not yet supported by ACadSharp
+	/// Unknown entities may appear in the <see cref="CadDocument"/> if the cad file contains proxies or entities not yet supported by ACadSharp.
 	/// </remarks>
 	public class UnknownEntity : Entity
 	{
@@ -47,7 +47,7 @@ public override string SubclassMarker
 		}
 
 		/// <summary>
-		/// Dxf class linked to this entity
+		/// Dxf class linked to this entity.
 		/// </summary>
 		public DxfClass DxfClass { get; }
 
@@ -62,7 +62,7 @@ internal UnknownEntity(DxfClass dxfClass)
 		/// </remarks>
 		public override BoundingBox GetBoundingBox()
 		{
-			return default;
+			return BoundingBox.Null;
 		}
 	}
 }

src/ACadSharp/IO/DWG/DwgDocumentBuilder.cs

@@ -1,5 +1,6 @@
 using ACadSharp.Entities;
 using ACadSharp.IO.Templates;
+using ACadSharp.Objects;
 using System.Collections.Generic;
 
 namespace ACadSharp.IO.DWG
@@ -14,6 +15,8 @@ internal class DwgDocumentBuilder : CadDocumentBuilder
 
 		public List<UnknownEntity> UnknownEntities { get; } = new();
 
+		public List<UnknownNonGraphicalObject> UnknownNonGraphicalObjects { get; } = new();
+
 		public List<Entity> PaperSpaceEntities { get; } = new();
 
 		public List<Entity> ModelSpaceEntities { get; } = new();

src/ACadSharp/IO/DWG/DwgStreamReaders/DwgObjectReader.cs

@@ -996,8 +996,6 @@ private CadTemplate readUnlistedType(short classNumber)
 				case "LWPOLYLINE":
 					template = this.readLWPolyline();
 					break;
-				case "MATERIAL":
-					break;
 				case "MESH":
 					template = this.readMesh();
 					break;
@@ -1019,9 +1017,9 @@ private CadTemplate readUnlistedType(short classNumber)
 				case "SORTENTSTABLE":
 					template = this.readSortentsTable();
 					break;
-				case "VISUALSTYLE":
-					template = this.readVisualStyle();
-					break;
+				//case "VISUALSTYLE":
+				//	template = this.readVisualStyle();
+				//	break;
 				case "WIPEOUT":
 					template = this.readCadImage(new Wipeout());
 					break;
@@ -1037,6 +1035,11 @@ private CadTemplate readUnlistedType(short classNumber)
 				template = this.readUnknownEntity(c);
 				this._builder.Notify($"Unlisted object with DXF name {c.DxfName} has been read as an UnknownEntity", NotificationType.Warning);
 			}
+			else if (template == null && !c.IsAnEntity)
+			{
+				template = this.readUnknownNonGraphicalObject(c);
+				this._builder.Notify($"Unlisted object with DXF name {c.DxfName} has been read as an UnknownNonGraphicalObject", NotificationType.Warning);
+			}
 
 			if (template == null)
 			{
@@ -1060,6 +1063,18 @@ private CadTemplate readUnknownEntity(DxfClass dxfClass)
 			return template;
 		}
 
+		private CadTemplate readUnknownNonGraphicalObject(DxfClass dxfClass)
+		{
+			UnknownNonGraphicalObject obj = new UnknownNonGraphicalObject(dxfClass);
+			CadUnknownNonGraphicalObjectTemplate template = new CadUnknownNonGraphicalObjectTemplate(obj);
+
+			this._builder.UnknownNonGraphicalObjects.Add(obj);
+
+			this.readCommonNonEntityData(template);
+
+			return template;
+		}
+
 		private CadTemplate readText()
 		{
 			TextEntity text = new TextEntity();

src/ACadSharp/IO/Templates/CadUnknownEntityTemplate.cs

@@ -1,7 +1,13 @@
 using ACadSharp.Entities;
+using ACadSharp.Objects;
 
 namespace ACadSharp.IO.Templates
 {
+	internal class CadUnknownNonGraphicalObjectTemplate : CadNonGraphicalObjectTemplate
+	{
+		public CadUnknownNonGraphicalObjectTemplate(UnknownNonGraphicalObject obj) : base(obj) { }
+	}
+
 	internal class CadUnknownEntityTemplate : CadEntityTemplate
 	{
 		public CadUnknownEntityTemplate(UnknownEntity entity) : base(entity) { }

src/ACadSharp/Objects/UnknownNonGraphicalObject.cs

@@ -0,0 +1,58 @@
+using ACadSharp.Classes;
+
+namespace ACadSharp.Objects
+{
+	/// <summary>
+	/// Class that holds the basic information for an unknown <see cref="NonGraphicalObject"/>.
+	/// </summary>
+	/// <remarks>
+	/// Unknown entities may appear in the <see cref="CadDocument"/> if the cad file contains proxies or objects not yet supported by ACadSharp.
+	/// </remarks>
+	public class UnknownNonGraphicalObject : NonGraphicalObject
+	{
+		/// <inheritdoc/>
+		public override ObjectType ObjectType => ObjectType.UNDEFINED;
+
+		/// <inheritdoc/>
+		public override string ObjectName
+		{
+			get
+			{
+				if (this.DxfClass == null)
+				{
+					return "UNKNOWN";
+				}
+				else
+				{
+					return this.DxfClass.DxfName;
+				}
+			}
+		}
+
+		/// <inheritdoc/>
+		public override string SubclassMarker
+		{
+			get
+			{
+				if (this.DxfClass == null)
+				{
+					return DxfSubclassMarker.Entity;
+				}
+				else
+				{
+					return this.DxfClass.CppClassName;
+				}
+			}
+		}
+
+		/// <summary>
+		/// Dxf class linked to this entity.
+		/// </summary>
+		public DxfClass DxfClass { get; }
+
+		internal UnknownNonGraphicalObject(DxfClass dxfClass)
+		{
+			this.DxfClass = dxfClass;
+		}
+	}
+}