In AutoCAD, a proxy is a representation of an external reference (xref) or a block that is created when the original object cannot be displayed or edited. Proxies are used to maintain data integrity and improve performance in large drawings that contain complex objects.
Why Are Proxies Used?
Proxies are used in AutoCAD for several reasons:
- Data Integrity: When an xref or block contains custom objects or complex entities that are not supported by AutoCAD, proxies are created to preserve the data integrity of the original object.
- Performance: Using proxies can significantly improve the performance of large drawings with multiple xrefs or blocks. Instead of loading and displaying all the details of an xref or block, AutoCAD only loads the proxy representation, reducing file size and enhancing system performance.
Types of Proxies
There are two types of proxies in AutoCAD: object proxies and graphics-only proxies.
1. Object Proxies
An object proxy is a lightweight representation of an xref or a block that contains custom objects. When an xref or block with custom objects is inserted into a drawing, AutoCAD creates an object proxy for each custom entity within the xref or block.
The object proxy stores information about the custom entity’s properties but does not display its graphical representation. This allows you to maintain data integrity while working on your drawing without being overwhelmed by complex details.
2. Graphics-Only Proxies
A graphics-only proxy is a simplified representation of an xref or a block that only displays its graphical elements without storing any additional information about its properties. Graphics-only proxies are commonly used when working with xrefs or blocks that contain complex geometry but do not have custom objects.
Unlike object proxies, graphics-only proxies do not retain any data integrity. They are purely used for visual reference and do not store any information about the original object’s properties or behavior.
Working with Proxies
When working with proxies in AutoCAD, it is important to be aware of their limitations and how they affect your workflow:
- Viewing Proxies: By default, AutoCAD displays proxies as bounding boxes or simplified representations. To view the proxy representation of an xref or a block, you can use the XDWGFADECTL system variable to control the transparency level of xrefs and blocks. A higher value will make the proxy more transparent, while a lower value will make it more opaque.
- Editing Proxies: Proxies cannot be directly edited in AutoCAD.
If you need to modify an xref or block that contains proxies, you must first explode the object to convert it into editable entities. However, exploding a proxy will remove its association with the original object, resulting in data loss.
- Purging Proxies: To reduce file size and improve performance, it is recommended to periodically purge unwanted proxies from your drawing using the PURGE command. This will remove any unused or unnecessary proxy objects from your drawing.
Conclusion
In summary, proxies in AutoCAD provide a way to maintain data integrity and improve performance when working with complex xrefs and blocks. Whether it is preserving custom objects through object proxies or displaying simplified representations using graphics-only proxies, understanding how to work with and manage proxies is essential for efficient CAD workflows.