Outside of the drawing management environment, you can use the AECVCOMPARE command to compare an open drawing to any other file that you select using the standard file navigation dialog. (At the Command prompt, type VCOMPARE if you have AutoComplete turned on; if you include the "AEC" prefix, you will only be offered the related system variables noted below.)
If one of the drawings you are using is an earlier version and the other a later version, the command works best if you have the more recent version of the file open, and compare it to a previous version, as it will treat items in the open drawing that differ from those in the selected drawing as "new" and differing items in the selected drawing as "old".
The image below shows a sample "original" file, with Walls, Doors, Spaces, Schedule Tags and some AutoCAD®objects.
The next image shows a copy of that file, with some edits made. The vertical interior Wall has been moved to the right, increasing the size of Office 101, decreasing the size of the other two Spaces and moving Doors 02 and 04. The text and linework at the bottom of the plan has been deleted, and some new text and linework has been added above the plan, at the left side.
As you can see on the Command line prompt, "old" items that no longer exist in the same location are shown in red, "new" items that did not exist in the same location are shown in green, and items that are the same in both files are shown in grey, using the out-of-the-box settings. Changes to the text are properly classified, but are shown using the txt.shx font, so the new and unchanged text will not completely overwrite the text in the current file if it uses a different font, as can be seen in the image, where the text uses the Arial font.
Five System Variables support the VCOMPARE command, and allow you to control the generated comparison graphics.
- AECVCOMPARENEWCOLOR - This variable determines the color in which "new" geometry (added items or items not in the same location in the file selected for comparison) is highlighted.
- AECVCOMPAREOLDCOLOR - This variable determines the color in which "old" geometry (items in the file selected for comparison which are either not present or not in the same location in the current file) is highlighted.
- AECVCOMPAREUNCHANGEDCOLOR - This variable determines the color in which geometry that is the same in both files is highlighted.
- AECVCOMPAREIGNOREHATCH - This variable determines whether differences in hatching are included in the comparison results. This includes the hatching in AEC objects, such as the Spaces in the image above, where this variable was set to OFF.
- AECVCOMPAREIGNORETEXT - This variable determines whether differences in text are included in the comparison results. This includes the attributes in Schedule Tags, but does not include other linework in the tags. In the image above, this variable was set to OFF.
While a comparison is active, you can use the options noted on the Command line to alter the comparison graphics. The "Old" option will show just the items in the file to compare that are either missing from or changed in the current file, along with unchanged objects in gray (turning off the green, new items). This can be helpful as the "New" graphics will cover the "Old" graphics when viewing both simultaneously.
The "New" option will show just the items in the current file that are either newly added or changed from what they were in the file to compare, along with unchanged objects in gray (turning off the red, old items).
You can use the "All" option at any time to return to the original display showing all of the comparison colors. When you are done comparing the files, you can press the ENTER key to exit the command. Pressing ENTER twice immediately after exiting the command (before executing another command) will repeat the command with the same comparison file.
If you are working in the drawing management environment, the process of initiating the comparison is somewhat streamlined, but the end results are the same. You can compare a previous version to the current version or you can compare two previous versions on the Check-In History pane. In both cases, the BAK file of the previous version(s) has/have to be available (not deleted due to exceeding the maximum number of backups). To compare a previous version to the current version, right click on the previous version and choose Visual Compare from the context menu. The current version will open, and a visual comparison to the old version will be generated. To compare two previous versions, select one, hold down the CTRL key and select the other, then right click and choose Visual Compare from the context menu. The more recent version will be opened, and a visual comparison to the older version generated. This can provide a quick way to identify what was changed between versions and may aid in making a decision on whether or not a file should be rolled back to a previous version.