Rhino v4
Is there a way to run FAIR on a curve and designate some points that are fixed and immovable?
Thanks C
Hi C- no way that I know of, I’m afraid.
-Pascal
Same question (at a later date) only the points to be fixed are where the curve to be faired intersects the end of a line. When I fair the curve it moves away from the key point. AND … assuming that is not possible, how can I cause the curve to move precisely back to intercept the end of the line. I have been futzing with its control points and can get eyeball close but I know it is not a snap-on match. I also tried the point function that finds the control point on the curve nearest the end point of the blue line then attempted to drag that point to the end point. It all looks great until the end - the line just plain doesn’t move.
maybe smooth helps instead of fair
dear @Jeffrey_David_Modell can you upload the curve in question. (3dm rhino 8 or older) please.
how does the control-point structure / distribution of the curve look like ?
Tried smooth, same problem but thanks for trying to help!
Use the command HBar (Not obvious.)
Make sure you have the appropriate Osanp on for the target location (End, Point, etc).
Start HBar
Click on the curve to modified. The HBar widget will appear.
Move the cursor along the curve to the location you want to move. The small circle moves but the widget does not follow. When the circle is at the desired location click and the widget will move.
Click on the center circle and drag the widge and curve to the new desired location.
Optional - You can now adjust the shape of the curve by moving the end points of the widget.
Right click/Enter to complete.
Thanks & triple thumbs up. I am floored by the responsiveness of the folks on this forum.
I have tried this. I have 3 key curve points that need to remain fixed. When I use this, only the last curve adjusted stays on point. The others, previously adjusted with this method, move. Can I lock them in place but allow their bars to adjust?
please - still waiting for your sample file
sample frame.dxf (173.3 KB)
Do a curve from the keel, running through the ends of the three blue lines, up to the middle area. Then match the curve to the vertical line (or use FAIR). Some of the curve will no longer touch the ends of the blue lines. That is what I want to stop from happening.
when you have only 6 Cp then that is expected. you have to increase the amount of points so that local areas which are not selected stay less to not affected at all. but smooth might not help much generally it in this case might be counterproductive.
on the other side your curve does not even hit the ends of the blue lines, not at a single intersection.
if you want to be sure the curve you draw goes exactly through the endpoints use InterpCrv, maybe use a degree 5 and the result will be a very fair curve already depending what you need.
Degree 5
Degree 3
interPCrv Degree 5
(Edit)
not in the file - but maybe the easiest approach might be to build an _interPCrv with degree 5 and set one additional Sample-Point between each fixed points.
turn on editPtOn and use Curvaturegraph to massage the (inbetween) edit Pts. (which feels a bit alchemistic …)
resulting in a curve with a bit more CV’s
it really depends on what you re after…/ the next step the curve is used for
File
sample frame_tom_p.3dm (3.0 MB)
bigger picture
you re building a ship hull at the end ?
so best do not focus on single curves but on the final surface.
my workflow is nothing magic, just moving CVs with less and less distance.
what s the tolerance for the curve you can accept ?
what s the usage for the data ?
kind regards - tom
Yes, it does not hit the ends of the blue lines because it was Faired or matched after having been set on them.
Someone replied to your post.
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Jeffrey David Modell:
Tried smooth, same problem but thanks for trying to help!
when you have only 6 Cp then that is expected. you have to increase the amount of points so that local areas which are not selected stay less to not affected at all. but smooth might not help much generally it in this case might be counterproductive.
on the other side your curve does not even hit the ends of the blue lines, not at a single intersection.
if you want to be sure the curve you draw goes exactly through the endpoints use InterpCrv, maybe use a degree 5 and the result will be a very fair curve already depending what you need.
i am not sure why you would post the broken geometry and not the initial then, but beyond what i told you there is not much more i can do i hope it helps!
Thanks, I will be trying it today!
Here is as far as I got on Fusion 360, which has no fairing capability. When a Ship forum friend showed me a base hull done on Rhino I got jealous. One of the things I need to balance in my mind is that the historical ships of this genre often had exaggerated lines that defied the concept of fairing vs. this particular model being among the last produced, most improved versions of the series. Further, I am not attempting to use the original construction methodology to revise the plans instead of merely proportioning up the draught of a different ship (though I am far from an expert) so this Rhino model will be a lot less rectangular than my 2023 version on Fusion.
The standing rigging drawing is where the research goes in. You need to get draughts, paintings, photos of contemporaneous museum models, and 18th century texts in Spanish to figure how to rig her! And you need to do the same for the various cannon. Plus, you need the parameters of the original ship. For example, we have poorly drawn (lines not straight, some not fair) draughts for this type of jabeque in 14 and 30 guns, but she has modified dimensions and is 34 guns! If you want to do a really fun type of model you need to draw each frame and its composition parts; this is just going to be a hidden wood bulkhead model. You can see how this soaks up your hours in retirement.
