In the following image I've overlaid 4 stages of (attempting) construction of a line in 3D mode. The line is to be aligned with an existing axis that is unaligned with the reference planes, and it is to be of a given length equally spaced either side of a point on the axis, here represented by the global origin.
From left to right:
- You select 'define line from center' and click the center point.
- It then won't let enter a value for the length until you've clicked another point on the axis
- When you click that point, the length is defined.
- And if you then edit the dimensioned length to the required size; although the dimension line changes to show the new dimension equally spaced around the middle, if you look closely at the top end of the axis, you'll see the dot-dash pattern of the axis showing between the end of the solid line and the dimensioned end of that line. (Note: At the bottom end, the solid line runs right upto the end of the dimension.)
In other words, it has only extended one end of the line with the result that the line length is incorrect if you measure it :
So, besides a pretty nasty bug -- because it is easy not to notice and only become aware after having done a lot more drawing using this incorrect length as reference -- can anyone see a workaround that doesn't involve drawing 3 lines and deleting two of them?