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@marko_ribar wrote:If you mean only 2d polylines that are parallel to WCS try this :
(sssetfirst nil (ssget "_X" '((0 . "*POLYLINE") (-4 . "&=") (70 . 0) (-4 . "<or") (210 0.0 0.0 1.0) (210 0.0 0.0 -1.0) (-4 . "or>"))))
That (70 . 0) won't find closed Polylines [for which the 70 value includes the 1 bit], nor those for which linetype generation is enabled [the 128 bit], either of which seem like common enough characteristics of contour lines, nor one that is perhaps less common: "heavy" 2D Polylines which have been fit- [the 2 bit] or spline- [the 4 bit] curved. [Also true of the routines in Messages 6 & 9].
Kent Cooper, AIA 
Please try attached ELEVLAYER.vlx, which puts objects into different layers based on their elevations.
Following steps below to select objects with certain elevations.
1. Change objects layer with ELEVLAYER. It will create layers named as ELEV-0, ELEV-980, ELEV-982, ELEV-1000, etc and put objects to the layer it belongs to.
2. In the Layer Manager, set up a layer with Filter Name "EEE". In the Filter Definition, set its "NAME" column to "ELEV-*0". So all layers names ends at 0 are included.
3. Click "All" in layer Filters column and turn all layers off (confirm turn off current layer).
4. Click "EEE" in layer Filters column and turn on all layers in this filter.
Now you can easily select the objects on desired elevations.
By the way, if the purpose is to set a special color to these objects on "Main Contour", you just get into the layer filter after Step 2 and change the layer colors.
@Kent1Cooper wrote:
@marko_ribar wrote:If you mean only 2d polylines that are parallel to WCS try this :
(sssetfirst nil (ssget "_X" '((0 . "*POLYLINE") (-4 . "&=") (70 . 0) (-4 . "<or") (210 0.0 0.0 1.0) (210 0.0 0.0 -1.0) (-4 . "or>"))))
That (70 . 0) won't find closed Polylines [for which the 70 value includes the 1 bit], nor those for which linetype generation is enabled [the 128 bit], either of which seem like common enough characteristics of contour lines, nor one that is perhaps less common: "heavy" 2D Polylines which have been fit- [the 2 bit] or spline- [the 4 bit] curved. [Also true of the routines in Messages 6 & 9].
My mistake, in part -- I didn't catch the (-4 . "&=") in there. I don't quite get how that's supposed to work from the description in the Developer's Guide, and haven't been able to find other examples of its use [even searching for "&=" in this forum doesn't find this thread!], but the function does find at least some of those types I thought it wouldn't. However, there's still something not quite right about it, because it also finds and highlights 3DPolylines that are not parallel to the WCS XY plane, and even those that are not planar and therefore not in or parallel to any plane.
Kent Cooper, AIA
@alanjt_ wrote:Kent, this may be of use:
....
Thanks, but that's all "old news." However, I'll take advantage of the chance to ask for some explanation, if anyone can provide it. What I'm having trouble figuring out is specifically the "&=" relational test, at least as used in some routines on this thread. That is described in part of what you attached, which I had already pondered in the Developer's Guide:
"&=" Bitwise masked equals (integer groups only)
Equivalent to: (= filter (logand bit filter))
They don't give any examples of its usage or syntax, and it's not at all clear to me what the relationship is between the concepts of "mask" and "filter," or whether maybe they're really the same idea, though if they are, I am puzzled at their using both terms.
So in the relevant part of routines on this thread, there's this:
(-4 . "&=") (70 . 0)
I think I understand that if, for example, you wanted to find only closed Polylines, you would "mask" or "filter" for the 1 bit that is part of the DXF 70 value if a Polyline is closed, and would use:
(-4 . "&=") (70 . 1)
and I did eventually find something that did that on-line. It would seem that the 1 in that must be represented by "filter" in the description, and the (cdr (assoc 70 edata)) value in a Polyline's entity data list must be represented by "bit." Then, whether the latter is 1 or 9 or 129 or whatever, substituting them into the description gives:
(= 1 (logand (cdr (assoc 70 edata)) 1))
which would be True for any closed Polyline. Similarly, if you wanted to find only 3DPolylines, which have the 8 bit included in their DXF 70 value, you would use:
(-4 . "&=") (70 . 8)
So my main question is, what does it mean to use 0 there? Converting to the equivalency terms in the description, it would seem to be checking whether this is True for a given Polyline before admitting it to the selection set:
(= 0 (logand (cdr (assoc 70 edata)) 0))
But that doesn't accomplish anything I can figure out, because
(= 0 (logand any-integer-at-all 0))
always returns True! So it seems to be checking nothing more than whether or not there's a DXF 70 entry in the entity data at all, because only if there isn't one will it return nil. That check is therefore redundant, as far as I can tell, since (ssget) is already filtering for "*POLYLINE" entity types, and all varieties of those have a DXF 70 entry, and no matter what value that holds, it will pass the test.
I think that's why the code lets in some things that it shouldn't -- non-parallel-to-the-XY-plane and even non-planar 3DPolylines.
So what does
(-4 . "&=") (70 . 0)
actually accomplish? Am I missing something? Any further clarification would be most welcome.
Kent Cooper, AIA
@marko_ribar wrote:I don't know, I thought it will mask (70 . 0) and (70 . 1), but not (70 . 😎 which was 3dpoly...
So I suppose this is unavoidable...
.... (setq ss (ssget "_X" '((0 . "*POLYLINE") (-4 . "<or") (70 . 0) (70 . 1) (-4 . "or>") (-4 . "<or") (210 0.0 0.0 1.0) (210 0.0 0.0 -1.0) (-4 . "or>")))) ....
That would then have one of the problems I first erroneously mentioned, that it would exclude Polylines with linetype generation enabled [128 bit]. One could let in LW & 2D Polylines that might or might not be closed and/or might or might not have linetype generation enabled, by adding more possibilities inside that OR grouping -- entries for 0, 1, 128 & 129. That's not too onerous, but if it's necessary to allow for Fit- or Spline-curved 2DPolylines [2 & 4 bits], a lot more possible combination values would be needed. I don't think the "&=" relational test can check for something not being there [the 8 bit to exclude 3DPolylines (but see below), and the 16/32/64 bits about Polyface Meshes], but maybe there's a way to do that.
Then there's also the question of whether they would want to include even 3DPolylines, if they are planar and parallel to the WCS X-Y plane.
It may be simpler to omit that particular narrowing-down within the (ssget) filtering, just grab all *Polylines with appropriate extrusion directions, then step through the selection and take out any that don't fit other criteria. 3DPolylines can be checked for planarity [is that a word?] with the (vlax-curve-isPlanar) function, Meshes can be eliminated by their second DXF 100 entry, etc.
Kent Cooper, AIA
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