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Polylines? What are those for!?


Outlander

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So here it is, 2008 and I am still drafting using line tool-arc tool-line tool-etc. then taking the combine tool to make all of these line segments into one simple segment. It almost seems to me that there should be a tool that can do this all at once. What's that you say? There is one! It's called polyline. Wow, I better check this out. Wait a minute though, I can draw straight lines but where are the arc functions that I'm used to and what the hell are bezier and cubic vertex lines. Not only that but how am I supposed to draft accurately with them. I know, I know, I'm being sarcastic, but imagine if they took all the functions from the arc tool and switched them to these functions. NO ONE in their right mind would use Vectorworks for drafting. And isn't that what Vectorworks is striving to become, a precise CAD software, not an imagery software like so many AutoCAD trained professionals regard it to be? I have discussed this issue with many people learning Vectorwork and it is obvious that this is the #1 problem keeping professionals from using Vectorworks for serious drafting exercises. It is also the most basic: the ability to draft complex line segments with precision and speed. So please, forget about colours, 3d modelling, and file extensions and get the basics nailed down first. It would save everyone who uses this program a significant amount of time.

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Well Jon, I do landscape architecture, and it's not always as simple as that we draft pathways, planting bed edger, retaining walls, etc. that have very curvy shapes and all I need is to be able to create lines and arcs that come off tangent to each other and it would be nice if I could do all that with one tool. Even if they just added the tangent to line arc and 3 point arc to the polyline functions I would be extremely happy. Nothing in this world would make me happier!

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Have just requested via my current exchange with Tech Support regarding ongoing problem with polylines (18 years) - "What is needed is a new vertex mode that places an arc between intersecting tangents by retaining the intersection point as the snap point & without placing an additional vertex along the tangent line, ie like highway design & land surveying software".

Jonathon, as an owner of your Manual for Landscapers, I find it surprising that you would suggest the way to draw curvilinear paths is as filleted boxes.

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I think he meant using filleted rectangles for drawing ovals and such. For some other shapes you might draw rectangles and circles and then use Add or Clip Surface. But for curving paths, you have to combine simple lines and arcs, as he said earlier.

Another option is to draw a straight-only polyline and then fillet it to create the curves. That's very helpful when you need a certain radius between two straight segments rather than needing to start the curve at a particular point.

It would be nice to have a new type of object, an arc-polyline that consists of lines and/or circular arcs, like that other program has. No matter how you create the current polyline the curves are more like splines, and when you offset them they're a mess.

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You can first draw the polyline with lines, then reshape the corners with circlesegments. You can set the radius. I do it all the time, and it is very accurate.

When I first started to use VW, I also thought it was not good. But Using this tool and abuse it in many ways learned me how it can be used a good fast and accurat way. Just try things out and you'll discover it strengts.

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DWorks would you elaborate on how you are getting a symmetrical curve about the tangent points of 2 intersecting tangent lines.

My polyline problem & subsequent request for an additional vertex mode as been forwarded by Tech Support to Engineering Wish List. Tech Support's suggestion was to convert closed polylines to polygons to get them to close, unfortunately, if converted from a closed polyline object to a polygon the object has thousands of vertexes & the vector geometry can not be edited (ie can not change the radius of arcs); not what is needed.

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We have an employee learning VW who was an ACAD user. Her biggest complaint so far is not being able to do exactly as Outlander describes. I also use the line tool-arc tangent-line tool.....method then compose. I usually go back and redraw the arcs with fillets using a whole number for the radius. This takes a while but gives me the result I am looking for.

VW does have the Polyline by Arc Point mode which will draw line tangents and also has the ability to enter a radius by clicking "i" but I have not gotten used to drawing this way. Maybe this tool needs to be refined or made easier.

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Bruce, draw a polyline consisting of 2 straight line segments. Then select the 3rd mode of the Fillet tool, set the radius you want, and click on the 2 segments. That adds a new curved segment to the polyline in between the 2 original segments, tangent to both and of the radius you specified.

But there are no vertices at the endpoints of the arc, and the radius may change if you reshape the polyline. And if you offset it, the curved part of the new polyline is actually a series of straight line segments approximating the curve.

Alternatively (and I believe this is what DWorks was talking about), you can draw the original polyline with an additional straight segment between the other two, with its endpoints at the start and end points of the curve. Then use the 3rd mode of the Reshape tool with the "Add a fillet vertex" option, specifying the radius, to create the curve.

That second method will give you vertices at the ends of the curve, but if you try reshaping it you'll see they aren't really endpoints of an arc. They're endpoints of a segment that always contains an arc of the specified radius and may also include straight lines on one or both sides of the arc. And the offset problem is the same as with the first method.

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The problem for an Ottocad user is that its polylines aren't made the same way as VW's are, and the VW type are more complex. The VW polyline can do a lot more than Otto's, but it's harder to understand and control.

Otto has a datatype called Spline, which consists only of curves, with no straight part. It's not really divided into segments, but is one continuous curving line whose shape is defined by control points on the curve and by the tangent to each end point of the whole curve. And then it has a datatype called Polyline, which is divided into segments, and each segment is either a straight line or a circular arc. The shape of each segment is defined by its two endpoints and its center point. No external control points in either case, except for the endpoints of the end tangent of a Spline.

VW's Polygon is similar to Otto's Polyline except that the Polygon can only have straight line segments -- no arcs. VW's Polyline is in some ways similar to Otto's Polyline, and in some ways similar to Otto's Spline, but it also has features that are unique to VW.

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DWorks .. thnx for the excellent tutorial. i use that technique frequently. Although, for the #4 offset .. i prefer to just duplicate & increase the existing circle radius so as to be certain of the correct fit ( using 00.0000000 units & degrees) ) thus avoiding the segmentation issues you mention.

Nevertheless, composing in these situations usually offers some challenges ; )

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DWorks - thanks for the info. My struggle is drawing road designs with many curves that are used to constrain vehicle speeds ("Liveable Roads for All Travellers"), that intersect with other roads & driveways. I need to offset the design centre-line of all roads & driveways with correct geometry to create pavement surfaces, curbs, sidewalks, drainage swales, landscaping & some cases utilities. Because the offsets have correct geometry then surveyed layout points & as-built COGO points can easily be checked against the design features. Most importantly is that the geometry (primarily radii of simple curves) must be correct & retained so that they can be changed to provide a design that best fits constraints such as: design standards, aesthetics, right-of-way, etc.

To further complicate the issue it is becoming imperative to be able to check all design features in 3D to ensure the proper clearance of all underground utilities.

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Very nice presentation, DWorks.

Using the Change Vertex mode and Circular Arc sub-mode of the Reshape tool has the same effect as using the Fillet and Trim mode of the Fillet tool, and the radius setting for either tool applies to both. I prefer using Fillet because I always keep it set at that mode, whereas I use many modes and sub-modes of the Reshape tool.

In addition to the advantages you mentioned, the curve thus created keeps its radius and its tangency to the adjacent straight parts of the segment when re-shaped, and the external control point is always the point where the adjacent straight lines would intersect. It's a little frustrating at first that you can't grab the end of the arc as a vertex and put that where you want it, but these features more than make up for that.

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