An exercise: DRAWING A PARISIAN FENCE
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@simon le bon said:
"As we havn't in SU a Bezier curve tool which is able to deal a curve of defined number and length of segments between two fixed points,...
I am actually not able to draw the curve needed.!!...
Please Taff, Can you give your solution!!??
Simon, I kept the 5-segment and 7-segment curves separate. (I didn't try to complete the entire hoop as one piece.)
For the 5-segment section, I set the SU "Arc" tool to 5 "sides," then started an arc from the bottom (tangent) upwards, toward, and ending on, the centerline (where it will eventually meet it's mirror image.)
I watched the length in the "Entity Info" box, and kept zooming in, on the endpoint, until the length was very close to 5.0 (so that each segment will be 1.0 unit long.) When I "exploded" the curve, I found that the length changes a little bit. By drawing curve-after-curve, I was able to "sneak up" on the correct length, by trial-and-error.
I kept the one curve that came the closest, and deleted the others. After exploding the retained curve, each line segment is accurate, to within 3-decimal-places ("1.000")
Once I had the curve, as a guideline, I could further subdivide it into smaller segments, to be used to construct the sine curve.
I constructed the 7-segment curve, using the same technique. I suspect that the Fredo-curved arc will provide comparable accuracy, as long as you don't try to make the entire hoop at one time. SketchUp's "tangent" inference made my method possible, even though I think other methods will work just as well.
@simon le bon said:
"Now for the angle of the diamond and the ability of SketchUp into such a preciseness,...
While your measurement is now "precise," I never used the angle to construct anything. Interesting intellectual exercise, but not important to making the model. If you want to rotate a 5-segment-long line, to meet a triangle centerline, you can use the technique described in this model, by Jean Lemire:
Rotating an edge to another edge
I hope my explanation is clear enough to help you pick up a "trick" or two; to polish your modeling skills.
-Taff
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@unknownuser said:
"It's maybe not a good idea to use the Shape Bender for a long parisian fence roll!
Better is make a texture from an image result!"
Pilou,
I agree. I look at this model as an exercise, or challenge, to improve modeling skills. Such a detailed fence would make a model very "heavy," because it introduces too many line and face entities.
For inclusion in a larger model, an image-texture, with transparent background, and some SU face trimming (for proper shadows) would be a much better option. If trimming is too complex, just turn off shadow-cast and shadow-receive checkboxes (in "Entity Info" dialog box.)
-Taff
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Dear Taff, first thank you so much for this documented reply. I Know so well how to produce documented pictures is time consuming.
I was seriously beginning to see myself with a too bad limited mind. After various false tries, I was turning around like a dervish. I was thinking of decompose (as you) the curve, but adjusting several portions of mathematical circular curves (ellipsoid) for which I had not the theoretical power to make any calculation..
So a great thank to you to have showed me what I was missing: modesty!!. When we haven't the theory nor the tool, it remains the " bricolage", But this can be a clean "bricolage" as you have done.
Since Su doesn't give the curve length in addition to the radii in real time into the VCB, going near by near as you do with simple portions of circle is the elegant solution.One of my interessant tries was to use Fredoscale's bend tool applied on a line with the exact length, bend it a little with the correct number of slices, and take bend tool again on this new well segmented curve but with a slice of One and bend it step by step. May be it is possible but I haven't reach to go to the end without bugs..
interessant tools:
Didier Bur Dim-AngleFredo Polyline Divider
I'm going for work until far in the night, so no try before tomorrow.
++simon
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I progress.
Thank you Taff for all the tracks you have left.
Very good exercise indeed.
Still some problems to resolve.
Not at home this week, hope a final point on Monday...
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- simon
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Simon,
Sine wave count and braiding looks good. You are to be commended for persevering, until achieving success!
-Taff
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Finally I've got mine
*s
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@simon le bon said:
"Is that the waves have to be regularly curved in the curved area?"
Simon, good catch.
Once I had established the curve, of 5 and 7 straight-line segments, I could then use the "arc" tool, to create new curves, of 35 and 49 straight-line segments (by multiplying by 7.)
I did this, only to more "smoothly" model the curve. It's not absolutely necessary, but isn't difficult, since the sine-wave amplitudes are already established. Incorporating the amplitudes into the new, smoother curve is relatively easy, using SketchUp's inferences.
-Taff
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Dear Taff,
I was to bring a pair of my tips for this exercise and was waiting for your validation and:::
@unknownuser said:
You are to be commended for persevering, until achieving success!
I thought I had finished my exercise??I open your skp to get an idea of what you mean!
Is that the waves have to be regularly curved in the curved area? I don't see what can you mean else
simon -
Dear Taff,
Re: Doing this way, we can't maintain the sine segments along the top of the fence exactly the same length!
Anyway, I would like to propose you some of the tricks I had previously talking about to achieve easily the round top of the fence as you wish .
YouTube SketchUp_ParisianFence_Tricks 1[flash=640,505:2smet3c3]http://www.youtube.com/v/EwExCv2ZTRw[/flash:2smet3c3]
using:
Component Stringer
BezierSpline
Projections
Lines to tubesNow I just have to do it for real
*s -
It was the trick N°1, what will be the n°2
The curious thing is there is no precise documentation on the Net about this sort of garden materail
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Hi Dear Pilou,
You always keep a vigilant and friendly eye
I guess you have noticed we all have followed your slices:
(The second trick after about a week to film "Rock'n Roll!!!!")
Dear Taff,
Here is my "final-final" parisian fence...
*s
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@simon le bon said:
I havn't discovered what was the mistake Taff was talking about
Simon, look here:
-Taff -
Simon,
I found that the key characteristic of the fence is the horizontal-to-vertical spacing. The diamond shape has to be exactly the correct proportions, or the sine waves of the top and bottom "rails" don't overlap properly. After a couple of false starts, I recognized my error, and got the diamonds the right shape.
I hope that I've provided enough detail, in the model, to demonstrate how I constructed the sine wave paths.-Taff
This model contains a mistake. Download corrected model from 3D Warehouse.
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Hi Taff,
I can't believe it I don't see the point
??simon
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oops!
With the animation I can see it very well now, thanks
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Next challenge--->(not very hard, but let see..)endless spiral
Btw in the images are 3(for a better visual impact).
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Excellent Eli.
No idea of how we can accomplish this? (nice model!!!)
Shall try when I'll be back (i'm connected by phone
)
*s -
I have succeeded to make my video "Trick 2" before to leave.
The first big problem was to draw "The Diamond" with the 6x and the two 5x lines . I have discovered with Taff and JeanLemire that Su suffers of a lack of inference and consequency we need a:
@jean lemire said:
Method to allow to rotate an edge around one end in order to bring the other end in contact with an other edge. This is something that the inference engine cannot do.
see: Rotating an edge to another edgeI bring here my own method using TIG_TrueTangents v1.9
The second big point was to manage curves of an exact length between two pointsSee Taff's close by close Solution. This is another very sensitive point where SU is in default.
I have taken great advantage of Fredo's Bend Tool set in FredoScale 2.0i
YouTube SketchUp_ParisianFence_Tricks2(sorry I couldn't be shorter )
[flash=640,505:3ig0nr8b]http://www.youtube.com/v/nobO28fyV-g[/flash:3ig0nr8b]
& TIG_Mirror 31
What Else?I havn't discovered what was the mistake Taff was talking about
@unknownuser said:I just discovered a spacing mistake I made in the top-rail/hoop area!
++simon
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Hi Ely,
I have succeeded without any spiral drawing tool
, but I could not avoid from doing important sewing work into one of the steps. I'll show you some process in the evening. I'm very curious to learn an easier way that I'm sure you know.
It is a good exercise, thanks!
s -
Here is my slow method
simon
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