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re: change line shape but not length?
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* March 10, 2014, 09:16:53 AM
TC18 pro:  Is it possible to take a line (shape immaterial) and change its shape without affecting its length.  Like you have a length of rope, and you can make it into any shape you want.  If possible - how?  Thanks Roger

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* March 10, 2014, 09:30:12 AM
#1
I've wanted to do that, too. Never did find a way.

Henry H

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* March 10, 2014, 10:00:45 AM
#2
Henry:  Uh Oh.  If you  can't do it ... nobody can.  It would be a very useful tool though.  Roger

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* March 10, 2014, 11:23:36 AM
#3
I think the closest you'll get is to use the "Edit Tool". Hold the "Ctrl" key to add nodes to the line, then move 'em around. Right-click on a bent section node and use "Insert Arc" to round it over. Maybe use "Convert to Curve" after that.

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John R.

V17—V21, 2015—2018
Designer, Deluxe, Expert, Basic, Platinum
RedSDK enabled
Windows 10 Pro, 64-bit


* March 10, 2014, 01:18:55 PM
#4
John:  I've played around with your suggestion a little.  Certainly is challenging.  Will work on it some more.  Thanks, Roger

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* March 10, 2014, 01:46:22 PM
#5
I looked at this again. Why not draw a Bezier curve between the two points, then use the Edit Tool. It'll bend better than a polyline.
« Last Edit: March 10, 2014, 01:49:39 PM by John R »

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John R.

V17—V21, 2015—2018
Designer, Deluxe, Expert, Basic, Platinum
RedSDK enabled
Windows 10 Pro, 64-bit


* March 10, 2014, 03:54:28 PM
#6
I looked at this again. Why not draw a Bezier curve between the two points, then use the Edit Tool. It'll bend better than a polyline.

Yup. But the only way I know to keep the length unchanged is to make a note of its value (in the Selection Info palette) before editing, then read the new value after editing and re-edit as necessary to restore the original value. Expect a good bit of trial-and-error.

Henry H

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* March 11, 2014, 04:50:24 AM
#7
Thanks for your continued thoughts.  I'm thinking the programing of this CAD feature might be a bit difficult, that's why it doesn't exist.  Roger

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* March 11, 2014, 05:25:55 AM
#8
TC18 pro:  Is it possible to take a line (shape immaterial) and change its shape without affecting its length.  Like you have a length of rope, and you can make it into any shape you want.  If possible - how?  Thanks Roger

Hi Roger
Though you haven’t given a specific example of what you’re trying to accomplish > Have you tried creating a custom line style? You can create and save custom “shape files”.  (.shx) These should be in your Tcad 18 documents folder (shapes)
> options
> drawing set up
> line styles
You can create some interesting and or useful line styles.

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"What do I know, I'm still learning"..
Windows 7 64 bit HP > on a stock HP laptop with 4gb-2.4 GHz.Turbocad 2019-2018-2017, TurboCad Platinum 21.Using Lightworks and Redsdk, Anilab lab 5. ATI Mobility Radeon HD 4500/5100 and HP all in one desktop with Nvidia Geforce 210, open gl 3.3


* March 11, 2014, 07:09:49 AM
#9
Hi Dean:  I'll take a look at the line shapes.  What generated the question is a parachute.  Suppose you have a drawing of the profile, and you pull down the vent (top).  The sides (gore lengths) stay the same length.  A CFD program (like an LS Dyna) would automatically adjust the shape; but I wanted something a bit simpler to draw various configurations.  Roger

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* March 11, 2014, 10:03:46 AM
#10
Here's a sample: I made two copies of a Spline and edited each copy to change its shape and still maintain the original Length as reported in the Selection Info palette (within a reasonable tolerance). Although some trial-and-error was involved, it really didn't take long.

Henry H

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* March 11, 2014, 10:08:35 AM
#11
Thanks Henry.  Not perfect but - I like it!  Roger

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* March 12, 2014, 04:31:46 AM
#12
Hi Dean:  I'll take a look at the line shapes.  What generated the question is a parachute.  Suppose you have a drawing of the profile, and you pull down the vent (top).  The sides (gore lengths) stay the same length.  A CFD program (like an LS Dyna) would automatically adjust the shape; but I wanted something a bit simpler to draw various configurations.  Roger

Thanks Roger, that’s a better explanation of your project.
Perhaps creating a Tcad nurbs (solid) surface of the parachute profile and use the” deform to point” tool.
You can adjust the nodes accordingly without changing the dimension of the object then extract your line in reference by tracing a spline over the shape.  Otherwise I think Henry’s method  would be the most useful.

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"What do I know, I'm still learning"..
Windows 7 64 bit HP > on a stock HP laptop with 4gb-2.4 GHz.Turbocad 2019-2018-2017, TurboCad Platinum 21.Using Lightworks and Redsdk, Anilab lab 5. ATI Mobility Radeon HD 4500/5100 and HP all in one desktop with Nvidia Geforce 210, open gl 3.3


* March 12, 2014, 05:33:00 AM
#13
Thanks Dean.  I can see how to make a 3D surface in the shape of  a parachute (like a half sphere) with a Revolve tool, with some effort I managed to make one using the loft.  I read up in the manual on using a 'deform to point' to deflect the surface, but am unable to pull down the apex as I would imagine.  Attached in the lofted surface.  Any suggestions.  Thanks, Roger

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* March 12, 2014, 06:12:47 AM
#14
This is a model of a 50s/60s Lotus racing car wheel, famous for its "wobbly web".  The web was essentially designed as a deformed cylinder of material, like the closure of a draw-string bag.  The splines of the loft are 6-period circular waves, and only the outer one needed laying out, the others are just scaled copies.  It's identical in concept to a suggestion that Henry offered to model a wave washer, and although I've used seven profiles, that's overkill for a chute, I'd reckon.   The file is an example of what three profiles can do, very exaggerated.  Adjust the height of the two smaller circles to adjust the shape.
« Last Edit: March 12, 2014, 06:27:52 AM by murray dickinson »

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* March 12, 2014, 06:31:14 AM
#15
Thanks Murray.  I downloaded your drawing 'Parachute1.TCW' and when I try to open it I get "No Filter matching this file".  Do you (or anyone) know how I can correct this problem?  Thanks Roger

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* March 12, 2014, 06:42:14 AM
#16
I'd opened yours in V20, this one's V17.

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* March 12, 2014, 06:45:33 AM
#17
Murray.  THANKS!

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* March 12, 2014, 06:48:43 AM
#18
Murray:  Accidentally posted before finished.  What you did was great.  HOW DID YOU DO THAT?  Can you give me a few pointers on where you set your nodes, which nodes you moved.  I tried a few times and can't do what you did.  Besides being ignorant, I'm also jealous.  Roger

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* March 12, 2014, 07:00:00 AM
#19
Three concentric circles, the height of the smaller two just lifted arbitrarily.  Lofted with compound profile, which isn't because it's a composite profile, it's because it associates the circles with the loft, ie change their arrangement (or their size) and the loft rebuilds to reflect the changes. 

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* March 12, 2014, 07:04:36 AM
#20
Murray:  As I understand it then, you set your circles than lofted.  I was trying to start with a lofted object, then 'pull down' the top to it looked basically like what you have.  Roger

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* March 12, 2014, 07:19:09 AM
#21
That's it.  It's adjustable afterwards, so placement can be arbitrary first, then eyeballed to get close to your curve.  Thinking on it, I reckon that your curve will be a section of a parabola, and you could trace the morphology from the before-and-after focal distance/depth ratios.

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* March 12, 2014, 07:47:02 AM
#22
That's it.  It's adjustable afterwards, so placement can be arbitrary first, then eyeballed to get close to your curve.  Thinking on it, I reckon that your curve will be a section of a parabola, and you could trace the morphology from the before-and-after focal distance/depth ratios.

Remember those Nike/Bo Jackson commercials back in the '80s?: "Bo Knows..."  Well...

Murray knows Geometry.... :D

I wish I knew 10% of what Murray knows; maybe I could make sense of 5% of what he tries to teach us. ???  -Alvin
« Last Edit: March 12, 2014, 08:08:11 AM by Alvin Gregorio »

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Alvin Gregorio
(mostly Residential Architectural 2D; no formal CAD Training; intermittent TurboCAD user since yr. 2000 [ver6.5])
---TurboCAD: V20.2PP(57.0)[as of 3/12/15]; V19DL(54.2); V11.2Pro; Windows-7-Pro/64-bit; Intel-Core-i3 CPU; 2.27ghz; 4GB RAM; Intel HD Graphics (CPU based)


* March 12, 2014, 07:57:45 AM
#23
Murray:  I'm a failure.  I took your loft, selected the 3D edit/ deform point  feature.  I was able to set 'nodes'.  So I set one in top center, and one in bottom center.  I relocated the top center to bottom center and got a really weird shape.  I undid it.  Made a copy along side the original.  Then fruitlessly tried to repeat the what I had done on one of them.  I was unable to do it on either.  I can select the graphic, but cannot put in any 'nodes/constraint points' to drag.  All I get after I identify the object is the 'selection box' to identify the node.  I just don't seem to get it ... yet. Roger

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* March 12, 2014, 03:01:48 PM
#24
Roger, I don't understand what you're trying to do with setting additional nodes or constraint points.  The profiles are associated with the loft by checking the 'compound profile' flag first, and editing the loft only requires editing the profiles' natural features: the relationship of the circles, their diameters, the coaxiality (or not) of their centres.  Sliding the circles up and down their z axes, and/or changing their diameter is all that it takes to change the size and proportion of the mushroom shape.

I suggest that you select both of the smaller circles and just pull the edges of the bounding box and watch to see how the shape of the canopy changes.   
« Last Edit: March 12, 2014, 05:04:10 PM by murray dickinson »

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* March 13, 2014, 05:28:59 AM
#25
Murray:  OK I got it thanks.  I was going through the 3D modify / facet editing / deform point feature.  Unfortunately the 'lengths' do not remain the same.  But still a neat tool.  Roger

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