To follow up on this: I have the same prolem, and if your block has a certain direction, it doesen't necessarily help to chose no for alignment. I need my blocks aligned with the line AND pointing in the right direction on the right side of the line, like in the first figure, not the next two.
Anyone got a tip?
create a new block where the contens within the blockdefinition are rotated by 180° (or mirrored, whatever you like).
- alfred -
Or, since dynamic block parameters are available in 2010, add an alignment parameter. They can be a little tricky to get used to, but are quite handy. You could specify them as either tangential or perpendicular... which ever works best.
I was having the same problem and that worked for me.. but the question remains.. How can you determine which way the Measure / Block insert is going to populate the line, curve or spline? Is there a way to know when making the block? In my case, I was trying to populate a diving and curving spline with 3D blocks that represented roadway pre-cast sections that were 29'-9 1/2" long by 8 feet wide by 16 inches thick and were tipped at a 4% slope or 2.2906 degrees from the X,Y, plane for a tunnel design project.
The insertion points of these panels were at 4 feet in from either side but 17'-3 1/2" from one end.. NOT in the center of the panel. I created the panels and tipped them using with the UCS in world expecting them to lay out along the Spline in a positive X direction but they ended up 180 turned so insted of a flat road surface they where like steps with the 17' end on the wrong side of the spline. I was expecting the panels to start at the high end I picked and then descend down the spline. Could it be that on a diving Spline, the operation needs to start low and proceed in a positive Z direction?
The Spline I picked was created by projecting a flat but curving Polyline to a surface that was created at depth by extruding a spline from the tips of recorded depth readings every 50 feet along that flat poly line. This was worked out by help in another Discussion group session a few months ago when the spline drawn through the points at depth was not lying directly below the surface polyline so that other vertical lines drawn down did not intersect the new spline.. by using "Projectgeometry" with the UCS option on the above polyline to the new surface created by extruding the other flawed spline horizontally with the extrude command and OSNAPZ set to 1, we were able to create a new 3D spline that DID in fact match the surface polyline perfectly.. Whew! That takes longer to explain than it does to do it..
Anyway, That is how the spline was created that I used for the measure operation but I have no clue why I couldn't control the direction and orientation of the blocks. IF anyone feels compelled to test this for themselves, I'll help.. Or if you know ways to avoid this "Duct-Tape & Bailing Wire" fix of redefining a block so the measure / block operation works in a logical way, I would like to know. Thanks,
For once I have to place many asymetric objects uniformly with Alignment
along a convex circular arc (2D). So I try Measure or Divide using my
Block but it flips my Block so it is aligned with the inside of the
curve (closest to the curve centre) not the outside and the blocks are
turned upside down. .....
Use the DIV+ and/or MEA+ command(s) in DivideMeasurePlus.lsp, which you can get here. Among the many other enhancements over ordinary Divide and Measure, they allow User selection of any number of objects, so that you don't need a Block defined, if that suits your need. And they have an option to place things [whether Blocks or copies of the User selection] at any angle Relative to the direction of the path object, rather than only 0 or Aligned -- in your case, I assume you would use 180 degrees to get the result you want.
.... but the question remains.. How can you determine which way the Measure / Block insert is going to populate the line, curve or spline? Is there a way to know when making the block? ....
It's a function of the "path" object, rather than of the Block -- if it were purely a function of the Block, you would need two different Block definitions oriented in opposite directions in order to allow the desired result for any path object. For some entity types, the direction in which a path progresses from start to end is always the same [Arcs and Circles and Ellipses always go counter-clockwise, in the case of Arcs even if they were drawn by three points in a clockwise direction]. For Polylines and Splines, you can determine the direction by picking the object and stepping through the vertices or fit/control points in the Properties box, watching where the X marker goes.
An alternative to the DIV+ & MEA+ commands with a Relative placement angle that I recommended before, is to reverse the direction of the path object to get the Blocks to face the other way. You can do that with the RD command in ReverseDirection.lsp, which you can get here. It works on objects of more entity types than AutoCAD's Reverse command, and in versions of AutoCAD predating that command. And unlike various other reversing routines I looked into, it correctly handles arc segments and varying widths in Polylines. However, it does change the entity type in some cases [e.g. Arcs and Circles need to be changed to Polylines, and Ellipses into Splines, in order to progress clockwise], so DIV+ and MEA+ are probably preferable in your case -- RD is intended primarily for the purpose of getting text- or shape- containing complex linetypes to show the embedded elements facing the way you want.
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