November 23, 2007

Multi-View Block Tools in AutoCAD® Architecture 2008

In preparing class materials for my class at AU, I discovered an issue with Multi-View Block tools in AutoCAD® Architecture 2008. The behavior varies and seems partially dependent upon the settings for Drawing Scale and Annotation Plot Size, but what appears to be happening is that instead of respecting the X-, Y- and Z-scale factors set in the Multi-View Block tool's properties, the X-scale factor is being multiplied by the annotation scale factor (a product of the Drawing Scale factor and the Annotation Plot Size) and that scale factor is used for all three scale factors (X, Y and Z). Occasionally, the first use of a Multi-View Block tool results in the annotation scale factor being applied twice. This effect holds true both for Multi-View Blocks whose view blocks are drawn at full size, and were to be inserted with scale factors of 1, as well as for unit-block-based Multi-View Blocks, which were intended to be inserted with X-, Y- and Z-scale factors representing the overall size of that particular use of the unit block, and which were generally not uniform. None of the view blocks associated with these Multi-View Blocks had any attribute definitions or any sort of text included. While this behavior is annoying enough for the Multi-View Blocks that were to be inserted with scale factors of 1, it becomes all but a deal breaker for the unit-block-based Multi-View Blocks, as having the scale factors preset in the tool properties is critical to getting those Multi-View Blocks inserted correctly and consistently.

Even more bizarrely, the scale factors reported in the Multi-View Block tool's properties actually change with no user intervention! You will have to take my word for it, but the Draeger Anesthesia Machine Multi-View Block was set up in the source file with the correct X-, Y- and Z-scale factors and a Multi-View Block Tool created from that source file; the scale factors in the tool are correct with the source file open and the active file. Starting a new file results in the scale factors changing, as shown below.
Placing an instance using this tool results in those same scale factors being applied.

In some tests, I found that eventually the correct sizes would be set, but other times the incorrect sizing persisted for as long as I could be bothered to keep trying. I also found that once a file started behaving correctly, there was no guarantee that after saving and reopening the file (especially if AutoCAD Architecture was shut down and restarted in between), that the correct behavior would continue.

I eventually found the following two options would get AutoCAD Architecture to respect the scale factors set in a Multi-View Block tool's properties. You may need to repeat one of these options after saving, closing and later reopening the file.

1. Manually running the MVBLOCKADD command (I typed in the command at the Command: prompt) and inserting a Multi-View Block resulted in subsequent uses of Multi-View Block tools scaling the inserted blocks correctly.

2. Inserting a Multi-View Block through a Multi-View Block type of AEC Content, either directly from the AEC Content tab of DesignCenter or through a Tool palette tool that references AEC Content (drag the content from the AEC Content tab in DesignCenter onto an editable tool palette) also results in subsequent uses of Multi-View Block tools respecting the scale factors set in the tool's properties.

You could just make AEC Content of all of your Multi-View Block content, but that requires maintaining a separate file for each Multi-View Block Definition, rather than having a single source file, and you can not set Layer Key Overrides on AEC Content tools, whereas you can do so on Multi-View Block tools. Given the hassle of manually typing the MVBLOCKADD command and inserting a Multi-View Block (especially if there are no Multi-View Block Definitions in the file, which would require placing one instance from the tool at the incorrect scale, inserting one instance manually and then probably erasing them both, as the first is incorrectly scaled and the latter may be on the wrong layer and may also not be correctly scaled), I have decided that it would be easier to create a non-plotting Multi-View Block Definition, make an AEC Content file for it and finally making a tool from the AEC Content file. This tool can be placed on the same Tool palette as the other Multi-View Block tools, used once to get the scales on the Multi-View Blocks to be respected, and then that instance erased or left in place, as it will not plot. Dragging and dropping that tool is much faster than manually running the MVBLOCKADD command.

The properties of the tool that invokes the AEC Content file for the non-plotting Multi-View Block are shown below. Note that there is no additional control over the insertion, other than that set in the AEC Content file, which does not allow for Layer Key Overrides.
Using this tool results in inserting the non-plotting Multi-View Block with the scale factors (all 1) set in the AEC Content file.

Once this block has been placed, the properties of the Draeger Anesthesia Machine Multi-View Block tool magically return to the values originally set on the instance in the source file used to create the tool...
...and using the tool now results in a correctly scaled instance of the Multi-View Block being placed.

I did not see this problem in the 2007 or earlier releases, and I hope the problem can be eliminated from the the 2009 release.