How can i draw an envelope path with perfectly symmetric handles ?

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tylerdurden
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Joined: Sun Apr 14, 2013 12:04 pm
Location: Michigan, USA

Re: How can i draw an envelope path with perfectly symmetric handles ?

Postby tylerdurden » Sun Jan 14, 2018 8:22 am

More food for thought...

Image
Have a nice day.

I'm using Inkscape 0.92.2 (5c3e80d, 2017-08-06), 64 bit win8.1

The Inkscape manual has lots of helpful info! http://tavmjong.free.fr/INKSCAPE/MANUAL/html/

Moini
Posts: 2849
Joined: Mon Oct 05, 2015 10:44 am

Re: How can i draw an envelope path with perfectly symmetric handles ?

Postby Moini » Sun Jan 14, 2018 8:54 am

The issue is that here, we only want to apply the transformation in one axis, ignoring the length of the arc, and not assigning points on the top line to those one the bottom arc by using regular distances, but just by using a straight line downward.

I couldn't find any way that allows to separate these completely (Bézier envelope, Envelope Deformation LPE, Lattice deform LPE, even Bend LPE), aside from just using the good ol' node tool and moving nodes upwards with Ctrl manually.

If you do it like TD with the grid of squares, you'd need to measure the length of the bottom arc to know how wide the deformed thing needs to be at the bottom.
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tylerdurden
Posts: 2119
Joined: Sun Apr 14, 2013 12:04 pm
Location: Michigan, USA

Re: How can i draw an envelope path with perfectly symmetric handles ?

Postby tylerdurden » Sun Jan 14, 2018 9:19 am

Moini wrote:If you do it like TD with the grid of squares, you'd need to measure the length of the bottom arc to know how wide the deformed thing needs to be at the bottom.

The bottom arc length is easily known. But the amount of distortion I applied needed to be about 3x the difference between the length of the arc and the top line.

There must be a formula, but I haven't got it yet.
Have a nice day.

I'm using Inkscape 0.92.2 (5c3e80d, 2017-08-06), 64 bit win8.1

The Inkscape manual has lots of helpful info! http://tavmjong.free.fr/INKSCAPE/MANUAL/html/

Moini
Posts: 2849
Joined: Mon Oct 05, 2015 10:44 am

Re: How can i draw an envelope path with perfectly symmetric handles ?

Postby Moini » Sun Jan 14, 2018 9:42 am

Right, just tested. It's weird.
Something doesn't work? - Keeping an eye on the status bar can save you a lot of time!

Inkscape FAQ - Learning Resources - Website with tutorials (German and English)

tylerdurden
Posts: 2119
Joined: Sun Apr 14, 2013 12:04 pm
Location: Michigan, USA

Re: How can i draw an envelope path with perfectly symmetric handles ?

Postby tylerdurden » Sun Jan 14, 2018 10:17 am

Seems quite complex, and the unfortunate result (so far) is that while the lateral distortion is improved with perspective, the bottom arc of the object no longer fits the envelope. :(
Have a nice day.

I'm using Inkscape 0.92.2 (5c3e80d, 2017-08-06), 64 bit win8.1

The Inkscape manual has lots of helpful info! http://tavmjong.free.fr/INKSCAPE/MANUAL/html/

Moini
Posts: 2849
Joined: Mon Oct 05, 2015 10:44 am

Re: How can i draw an envelope path with perfectly symmetric handles ?

Postby Moini » Sun Jan 14, 2018 10:42 am

Maybe our math-savvy Lazur can guess what is happening?
Something doesn't work? - Keeping an eye on the status bar can save you a lot of time!

Inkscape FAQ - Learning Resources - Website with tutorials (German and English)

SUMATORIO
Posts: 33
Joined: Sat Jun 22, 2013 12:51 am

Re: How can i draw an envelope path with perfectly symmetric handles ?

Postby SUMATORIO » Thu Mar 15, 2018 5:07 am

Hi Raspi:

The easier way for me, to do it:

Make a horizontal line.
Duplicate with clon (Alt +D) Shift downwards with Ctrl key.
Flip vertically the clon.

Make a line to joint the left nodes of the horizontal lines with Beziers pen. Use the snapping bar to be accurate.
Duplicate this line and shift it at the right to snapping the right nodes.

Edit nodes in the line father. Select both nodes and ad another one, this will set at midpoint.
In edit node tool, select the node in the midpoint in the father line and bend downward (with Ctrl key down vertically)), the clone will bend symmetrically because it's the same line the father with flip.

You can then select the four lines and group them.
If we want to make a only object, after you have the desirable bend, desconect the clon, with Shift + Alt + D keys.
Select the lines adjunct and in node edition tool, select nodes and apply the icon join nodes. The same for the rest of segments.

Fill the object to check the unios of segments.

I hope to answer your question.

SUMATORIO
Posts: 33
Joined: Sat Jun 22, 2013 12:51 am

Re: How can i draw an envelope path with perfectly symmetric handles ?

Postby SUMATORIO » Thu Mar 15, 2018 7:05 am

SUMATORIO wrote:Hi Raspi:

The easier way for me, to do it:

Make a horizontal line.
Duplicate with clon (Alt +D) Shift downwards with Ctrl key.
Flip vertically the clon.

Make a line to joint the left nodes of the horizontal lines with Beziers pen. Use the snapping bar to be accurate.
Duplicate this line and shift it at the right to snapping the right nodes.

Edit nodes in the line ( father). Select both nodes and ad another one, this will set at midpoint. Change this node to soft node.
In edit node tool, select the node in the midpoint in the father line and bend downward (with Ctrl key down vertically)), the clone will bend symmetrically because it's the same line the father with flip.

You can then select the four lines and group them.
If we want to make a only object, after you have the desirable bend, desconect the clon, with Shift + Alt + D keys.
Select the lines adjunct and in node edition tool, select nodes and apply the icon join nodes. The same for the rest of segments.

Fill the object to check the unios of segments.

I hope to answer your question.


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