Construction Line Commands
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Attach drawing files and screenshots.
Post one question per topic.
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alex_holden
- Newbie Member
- Posts: 8
- Joined: Wed Dec 07, 2016 10:55 am
Construction Line Commands
I was just poking around in the Misc menu and I noticed Misc->Draw->Horizontal Construction Line (XH) and Vertical Construction Line (XV). What are they for? They appear to do exactly the same thing as Draw->Line->Horizontal Line (LH) and Vertical Line (LV). Looking in the property editor, the only difference I can see is that the Fixed Angle property is Yes for construction lines and No for normal lines, which doesn't seem to make any meaningful difference to the appearance or behaviour of the line?
Re: Construction Line Commands
Hi,
The single difference is that a 'normal' or line based XLine is defined with 2 points: Base Point & Second Point.
For this type there are two reference markers when selected.
With a fixed angle there is only a direction and no configurable Second Point and thus no second reference marker.
For this fixed angle type the Second Point & Directional Vector properties are grayed out.
Underneath all XLines are defined by a Base Point and a directional vector.
The second point is thus the sum of the two vectors and the directional vector is the difference between both points.
When created as a fixed angle XLine the directional vector is 1 unit long.
But you can clear the fixed angle property and look for the second marker what will be 1 drawing unit away from the base point.
One can also change the type of line based XLines but then the original directional vector is preserved and not unified.
IMHO methods LH & LV should create the fixed angle type because the user doesn't indicate a second position.
And the same for all line commands in Infinite Line mode without a user defined second position.
Regards,
CVH
The single difference is that a 'normal' or line based XLine is defined with 2 points: Base Point & Second Point.
For this type there are two reference markers when selected.
With a fixed angle there is only a direction and no configurable Second Point and thus no second reference marker.
For this fixed angle type the Second Point & Directional Vector properties are grayed out.
Underneath all XLines are defined by a Base Point and a directional vector.
The second point is thus the sum of the two vectors and the directional vector is the difference between both points.
When created as a fixed angle XLine the directional vector is 1 unit long.
Not much, the fixed angle type can not be re-oriented by dragging the second reference marker.alex_holden wrote: ↑Sun Oct 01, 2023 7:22 amwhich doesn't seem to make any meaningful difference to the appearance or behaviour of the line?
But you can clear the fixed angle property and look for the second marker what will be 1 drawing unit away from the base point.
One can also change the type of line based XLines but then the original directional vector is preserved and not unified.
IMHO methods LH & LV should create the fixed angle type because the user doesn't indicate a second position.
And the same for all line commands in Infinite Line mode without a user defined second position.
Regards,
CVH
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alex_holden
- Newbie Member
- Posts: 8
- Joined: Wed Dec 07, 2016 10:55 am
Re: Construction Line Commands
Oh, I understand now! Thanks for the explanation.
Re: Construction Line Commands
# EDIT #
Once saved and reloaded all XLine's and Ray's return with a unified directional vector.
Basically not problematic unless you count on the fact that the second point remains preserved ...
Stumbled on it while scripting under QCAD ...
Impossible to detect afterwards because the Fixed Angle property remains untouched as if the second point was created at 1 unit away.
Regards,
CVH
Should be: ... preserved and not unified in this QCAD session.
Once saved and reloaded all XLine's and Ray's return with a unified directional vector.
Basically not problematic unless you count on the fact that the second point remains preserved ...
Stumbled on it while scripting under QCAD ...
Impossible to detect afterwards because the Fixed Angle property remains untouched as if the second point was created at 1 unit away.
Regards,
CVH