Body.md

Body Class

Overview

Body is a generic wrapper for an ACIS body that doesn't fit strictly into Solid3d (solid volume) or Region (planar area) categories. It is often used for:

• Sheet bodies (surfaces).
• Wire bodies (3D wireframes).
• Bodies resulting from failed boolean operations or indeterminate states.
• Converting between other 3D formats.

Namespace

Autodesk.AutoCAD.DatabaseServices

Inheritance Hierarchy

System.Object
  └─ RXObject
      └─ DBObject
          └─ Entity
              ├─ Body

Key Properties

Inherits most properties from Entity.

Property	Type	Description
IsNull	bool	True if the internal ACIS pointer is null.

Key Methods

Method	Return Type	Description
SetBody(IntPtr)	void	Sets the internal ACIS body pointer (Advanced).
GetBody()	IntPtr	Gets the internal ACIS body pointer.

Code Examples

Example 1: Creating a Body check

// Bodies are rarely created directly via "new Body()".
// They usually result from modeling operations or import.
Body body = ent as Body;
if (body != null)
{
    // It's a generic ACIS body
}

Example 2: Converting Solid to Body

// Sometimes detailed analysis requires treating a solid as a generic body
// This is more common in ObjectARX (C++) than .NET

Example 3: Using Body for BREP (Boundary Rep)

using Autodesk.AutoCAD.BoundaryRepresentation;

// Use the BREP API to analyze topology
using (Brep brep = new Brep(someEntity))
{
    foreach (Autodesk.AutoCAD.BoundaryRepresentation.Face face in brep.Faces)
    {
        // Analyze faces of the body/solid/region
    }
}

Example 4: Identifying ACIS Type

// Since Body is generic, it's hard to know what it is (Sheet? Wire?)
// Often checking Mass Properties or using Brep API is needed.

Example 5: Exploding complex imports

// Imported STEP/IGES files often come in as Bodies
// Exploding them might yield Surfaces or Curves
DBObjectCollection parts = new DBObjectCollection();
body.Explode(parts);

Example 6: Validity Check

if (!body.IsNull) 
{ 
    // valid 
}

Example 7: ACIS Modeling Integration

// Body is often used as a bridge to external kernels or legacy SAT files

Example 8: Handling "Sheet" Bodies

// A "Sheet Body" (surface) in ACIS terms is often wrapped as a Body entity in AutoCAD
// rather than a Surface entity (which is newer).

Best Practices

1. Prefer Specific Types: Use Solid3d or Surface classes if possible. Body is a catch-all fallback.
2. Brep API: To do anything useful with a Body (measure, analyze), you usually need the Autodesk.AutoCAD.BoundaryRepresentation namespace.
3. Performance: Like all ACIS wrappers, they are heavy. Dispose when done.

Related Objects

• Solid3d
• Region

References

• Autodesk Body Reference