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Better Tangent Snapping for Circles and Arcs



One of my longest standing wishlist items that I am only now posting to the forum has to deal with snapping tangents from an object to a curved/arced object. Be it a circle, arc, arc-polyline, the tangent snap point does not work when drawing an arc or polyline to that feature. To better illustrate the problem I put together a short screenshot video.


I have also linked another thread because of it's relevance to the situation


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Vectorworks tangents capabilities seem often to defeat me. Am I missing some mode or method for creating lines tangent to other objects? Or should this just be resubmitted to Wish List?


For instance, if I have a wavy polyline made of connected (tangent) arcs forming "hills" and "valleys", and I want to draw a horizontal line tangent to the highest point on the poly . . .  Or, draw a horizontal line, then drag it until it snaps to highest point . . .


With the snaps set as shown, I can acquire the edge, click to start a line on the top arc segment of the poly.

The new line rubberbands tangent to the arc depending on my cursor position, but . . . 

A. The angle extensions and snaps for Horizontal, Vertical and any usual intermediate angle snaps are inactive.

B. Tabbing into the Angle field of the smart cursor allows me to enter angle of 0.00°, but this has no effect on placement of end point of the new line. Pressing Return key ends the new line at position of the cursor, not at designated angle.

C. Tangency to this Polyline is limited to the arc segment where the edge was acquired.  ie, my new line does not follow tangent to adjacent segments of the poly. This leads to strange placement options for the new line where start point is on the virtual circle extended from the arc, but not on the poly.

D. Strangely, the polyline's bounding box may be taller than the highest peak (why?), so even the Align command does not necessarily make a horizontal line tangent to the highest point on the line. Try this with the poly and the line in attached vwx (v2017).


More whining:

1. Same behavior if Line tool is constrained or unconstrained mode.

2. If the target Poly is Cubic Spline or Bezier segments rather than Arcs, the Tangent snap does not read the poly at all for start of a new Line object. 

3. Tangent snap can only acquire tangent to existing objects at either start or end of new object, but not both - eg I cannot draw an arc tangent to a circle at start click, and tangent to a second object at end click.

4. The Parametric Constraints tools have a constrain tangent mode, but that works by forcing the target object to move - never useful for me.

5. Whine whine whine


I can usually devise a workaround with knowledge of geometry, old school drafting techniques, arc radii, the Align commands, guide objects, the Fillet Tool, "close enough" with extreme zoom in, or other.  But, sheesh!  Computers & CAD are supposed to be good at this stuff.







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20 minutes ago, Benson Shaw said:

Vectorworks tangents capabilities seem often to defeat me. Am I missing some mode or method for creating lines tangent to other objects? Or should this just be resubmitted to Wish List?


I'm pretty sure you're not missing anything...... I have the same issues all the time. I'm glad to see I'm not the only one leveraging the Align command to solve weird geometry layouts. +1000 for the wish list.



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@ericjhbergyes!  I think many years of wanting this functionality is well described in your video. Thanks!

@Alan Woodwellyes. That's one of the objectives. Do you have a way to make this work consistently? (you da master!) Sometimes this works with Align command, but not always. Depends on the source objects.  Try the poly and straight line in my file. My wavy poly is a spline converted via Poly Smoothing>Arcs, so has arc control points which are not on the poly - screen shot attached. Dragging the line to expected top may just snap to a control point. Align command will read the poly extents with same result - Top of hill will be the highest control point rather than highest point on the poly. See also PS comment below.

@Kevin McAllister Many other users, and many posts wishing for better tangency- I think you may have put in one or more improvement requests for this. Pretty sure I did.


Anyway, for now, back to the workarounds.





Another confusing tangent situation:  Drag a horizontal line toward expected top of an arc poly.  Vectorworks smart cursor will indicate a tangent point on the extension of the drag direction by displaying a little circle where the drag extension line would be tangent to the poly.  If not zoomed in, this drag direction tangent point could be confused for a point where the line object is tangent to "top" of the poly.


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@Benson ShawHi, all i did was to draw a poly with straight segments then used the change vertex mode to get the curve i wanted, this gets the curved line. then and I clicked on the curve to draw a line on the edge of the curve and it flows around. then bring it to close to horizontal and click shift to force horizontal and click to set horizontal line. Then to extent the line i grab the end of the line at the apex and drag left to keep horizontal.

Hope this makes sense. Could be a faster option for VW to add in.

The image attached came from open GL option. Noticed in wireframe not as close.



Edited by Alan Woodwell
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Hey, Alan - Thanks for testing.  I did not mention my orig post (complaint A) that holding the Shift key to constrain Horizontal gets disabled when the tangent snap is in progress.  I do the same steps you describe - hover to acquire the poly edge, click to start a line on the poly. The line's angle and start point flow around the arc to remain tangent while mousing to establish the end point.  On my system, no matter how close I drag the line to horizontal, the Shift key does not constrain the line to Hor/Vert or the other constrained angles (on my system, it's the default Hor/Vert, 30° and 45°). The shift/move/click constraint and the smart cursor cues and extension lines work if the tangent snap is off, but they do not work at all if the tangent snap is on.


Also, if not active in a tangent operation, eg just drawing a line,  tabbing into the angle field, and entering 0, then press Rtn (or dbl Rtn) forces the line to horizontal.  If drawing a line tangent to a curve with tangent snap on, adjusting values in the cursor fields has no effect.


Hence my continued consternation!



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Argh! Trying to get a circle to 3 tangent objects should be there in VW like Autocad. Autocad, 3 seconds max, VW, hours of complicated geometry. This is a nightmare for me trying to draw gothic windows! Try as I might there is no-one in the VSS willing to help me with this. I submit and get "VW can't do this" or what is worse NO FEEDBACK AT ALL. Not good enough.


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Forgive the cheesy music but I have wanted this in Vectorworks for a LONG time. I have now had to set on Autocad LT just for the following command. I need it too much to be trying to puzzle out the geometry. It is a life saver/time saver for me.......  if only VW had implemented it! Works with lines, arcs or circles within seconds (usually 2 secs max). I've waited far too long for it and didn't find Support able to help me on how achieve it in VW - hence the new Autocad LT subscription last week to save VASTS amount of time. My gothic windows are now "doable" at last..... I have tangent snaps!



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