Convertpoly

[HybridAWD]

A few questions:

What does it does specifically? Convert polylines to...

What is the purpose of using it?

What causes someone to have to use it?

I use it, but sometimes, when something doesn't work, then I use it, it works again. So I am trying to better understand the background of this command. Thanks!

[Data Wrangler]

Another 'history of Autocad' post:

As you may know, Autocad is fundamentally a viewing package for a database of information on whatever it is you are trying to design. Each object (line, point, layer etc.) has to be stored in this database somewhere in a format that the program can retrieve and work on easily. When Autocad was first written, decisions on how the data were to be stored were made. Some of these changed in later versions. Polylines was one of these.

The first way polylines were stored was to have one record in the database (POLYLINE) for the polyline itself, and a separate record for each of the points (vertexes) that make up the polyline. This is the "heavy" polyline format. You can use the 'list' command on a polyline and see what type it is by looking at the records that come up.

The problem with this format is that it takes up a lot of room in the database, a real problem for things like contour lines on a civil map.

So Autodesk added a new way of storing polylines: the "lightweight" way (or LWPOLYLINE). This takes all of the vertices in a polyline and stores them as part of the overall polyline record. (again, use the 'list' command to see the difference). This took place around Release 14. This format has a lot less database overhead and is stored more compactly.

The problem with the lightweight format is that programs that were written to deal with polylines at the vertex level had to be rewritten to use the new polyline format. Apparently, Rebis/Bentley has never seen the need to do so and so we deal with their decision as needed.

The system variable in Autocad that dictates which one is used is PLINETYPE (look it up in the Acad help).

By using the 'convertpoly' command, you change the storage format of the polyline from one to the other. Since P&ID is only capable of using the 'heavy' format, you change your polylines to the old type so the package works correctly.

[Data Wrangler]

Why do the lines change? Good question.

[HybridAWD]

So there a predetermined location on whether or not Light or Heavy is used? Such as the LISP file or something similar?
I created this project with AutoCAD 2K4, and now we are at AutoCAD 2K6, so could that be some reasoning behind it?

Great background information though, big help in understanding it.

[Data Wrangler]

I'm hoping the Bentley guys jump in here to give us some direction...

But in reseaching the post above I found out that the PLINETYPE variable (which determines which polyline type is used) is stored in the registry instead of the drawing, as I had assumed. This means (I'm thinking) that I need to run around to the 16 or so machines and make sure it is set to 0 on everyone's install for every version of Autocad.

You can also check out the other thread ( http://www.davetyner.com/forum/showthread.php?t=149) for the other stuff I'm doing.

Derek