## [Behaviour suggestion] Sketcher_ConstrainSymmetric

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Shalmeneser
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### [Behaviour suggestion] Sketcher_ConstrainSymmetric

Code: Select all

``````* Selection before tool only
* '+' = 'then'
* '&' = 'and' (no order)

TODAY  :)
* 2 points + 1 (center) point --> 2 symmetric points around the center point
* 2 points & 1 line /axis     --> 2 symmetric points around the line / axis
* 1 line & 1 (center) point   --> symmetric line around the center point

TOMORROW  8-)
* 1 line & axis               --> symmetric line around the axis
* 1 line + 1 (center) line    --> symmetric line around the center line
* 1 line                      --> symmetric line around the 'best' axis
* 2 points                    --> 2 symmetric points around the 'best' axis

(best) : each side of an axis (2 axis = origin) OR smaller angle change
``````
chrisb
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### Re: [Behaviour suggestion] Sketcher_ConstrainSymmetric

I like the first very much, the second pretty much (not sure if it is intuitive). Don't understand the concept of best axis.
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GeneFC
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### Re: [Behaviour suggestion] Sketcher_ConstrainSymmetric

I think I understand "best", but I do not think it is a good idea.

If the program chooses the "best" axis then the operation tends to be unstable. A location of the line that is only one micron different could completely change the final orientation after the symmetry operation.

That sort of rapid output change for a tiny input change should almost always be avoided in programming or mechanics.

Gene
Shalmeneser
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### Re: [Behaviour suggestion] Sketcher_ConstrainSymmetric

GeneFC wrote: Sat Jan 15, 2022 3:20 pm If the program chooses the "best" axis then the operation tends to be unstable. A location of the line that is only one micron different could completely change the final orientation after the symmetry operation.
This is just for sketcher symmetry selection mode. At the end, you have the same symmetry constraint with 2 points around a point/line than today.
If the 'best' choice seems an error, just ctrl-Z it.
Shalmeneser
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### Re: [Behaviour suggestion] Sketcher_ConstrainSymmetric

Examples of selection on just one line. Just finding the 'best' axis.
Attachments
BEFORE
Capture du 2022-01-15 23-35-56.png (6.63 KiB) Viewed 333 times
AFTER
Capture du 2022-01-15 23-36-36.png (7.29 KiB) Viewed 333 times
GeneFC
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### Re: [Behaviour suggestion] Sketcher_ConstrainSymmetric

Shalmeneser wrote: Sat Jan 15, 2022 10:34 pm If the 'best' choice seems an error, just ctrl-Z it.
I was thinking of the problem of flipping that was brought up again just in the past day. Someone was using a spreadsheet to control the sketch.

I understand and agree that anyone working "live" could easily reverse any unwanted choice.

Gene
TheMarkster
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### Re: [Behaviour suggestion] Sketcher_ConstrainSymmetric

Shalmeneser wrote: Fri Jan 14, 2022 2:46 pm

Code: Select all

``````* Selection before tool only
* '+' = 'then'
* '&' = 'and' (no order)

TODAY  :)
* 2 points + 1 (center) point --> 2 symmetric points around the center point
* 2 points & 1 line /axis     --> 2 symmetric points around the line / axis
* 1 line & 1 (center) point   --> symmetric line around the center point

TOMORROW  8-)
* 1 line & axis               --> symmetric line around the axis
* 1 line + 1 (center) line    --> symmetric line around the center line
* 1 line                      --> symmetric line around the 'best' axis
* 2 points                    --> 2 symmetric points around the 'best' axis

(best) : each side of an axis (2 axis = origin) OR smaller angle change
``````
Seems to me the first 2 would be fairly simple where when line1 and line2 are selected or where line1 and axis1 are selected we treat it as if the selection was line1-point1, line2, line1-point2 (or line1-point1, then axis1, then line1-point2).

For the "best" options it could be sensible to presume the origin when only a single line is selected. This would be consistent with other operations, such as setting a horizontal length constraint and only a single point has been selected, in which case the origin is presumed.