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[Solved] Semi-Circular Lines

PostPosted: Mon Jun 20, 2016 8:18 pm
by JustBaffled
I use Draw to do simple 2D sketches. I'd like to draw a semi-circular line. I have managed eclipses and closed semi-circles but I can't seem to draw a simple semi-circular line. I've tried Help but I'm getting nowhere, it's obviously me but I would be grateful for any advice offered.

JustBaffled

Re: Semi-Circular Lines

PostPosted: Mon Jun 20, 2016 9:01 pm
by floris v
From the Basic shapes select Circle sector, with a three quarter circle as its icon. Draw it, then adjust the angle with the
 Edit: yellow 
circles at the end of the sector.

Re: Semi-Circular Lines

PostPosted: Mon Jun 20, 2016 11:58 pm
by keme
AFAIK there is no tool to directly draw an open sector arc (without the "slice lines" going to center).
 Edit: I now know better. See acknak's post below. 

Workaround:
After drawing the closed semicircle, remove fill and convert the shape to a polygon. Open the closed shape and delete the part that goes through the circle center.

Detailed procedure:
With your shape selected...
  • Find the fill type field (pulldown tool on the toolbar that probably says "Color"). Select "None" for fill.
  • Select menu item Modify - Convert - to polygon
    After converting to a polygon, you cannot easily change the sector angle. It is not a circle object anymore.
  • With the converted shape selected, click the Edit points tool (or press F8).
    Your polygon shape is now marked with a square placeholder for each "corner point". The squares will most likely overlap, and cover the entire curved line. Don't worry about that ;-)
  • Several point editing tools will have appeared on a points toolbar. Find the slanted triangle called "Close bezier". It should appear as a pressed button. (You may need to click the "more tools" arrow at the end of the toolbar to find that tool.) Click that button so it pops out to "open" the shape.
  • At one end of the curve, the squares should appear slightly larger (barely noticeable). That is the point where the shape is broken, or opened. Click that corner and then delete. One of the unwanted lines should vanish. Then click the center point and delete again. Done!

Re: Semi-Circular Lines

PostPosted: Tue Jun 21, 2016 2:20 am
by acknak
keme wrote:AFAIK there is no tool to directly draw an open sector arc (without the "slice lines" going to center).

There is an open, circular arc tool but you have to add its palette to the Drawing toolbar; it's not in the default configuration.

If you want to use it:

Tools > Customize > Toolbars > Drawing ... (or use the drop-down menu on the toolbar)

Click "Add" ... Category: Drawing, Commands: Ellipse, click "Add" and Close/OK out of all the dialog windows.

Note that there are two "ellipse" commands in the list. Check the description that appears below the lists and select the one that refers to the "Circles and Ovals Toolbar".

Once you have that new item on the toolbar, you have access to several kinds of arcs/pies.

To make an exact semicircle, hold Shift while adjusting the endpoints. That "snaps" the arc angles to multiples of 15°.

Re: Semi-Circular Lines

PostPosted: Tue Jun 21, 2016 7:47 am
by keme
acknak wrote:There is an open, circular arc tool but you have to add its palette to the Drawing toolbar; it's not in the default configuration.
...
Great! Didn't find it at home, late night, using LibreOffice on Linux. Here at work, bright and early, using OpenOffice on Windows, I found it at once.
Will check back this evening, but I was probably just too tired yesterday... Thanks Acknak!
Everyone else: Please forgive and forget the useless recipe in my previous post. :-(

Re: Semi-Circular Lines

PostPosted: Tue Jun 21, 2016 6:33 pm
by JustBaffled
Acknak and All,

Thank you, brilliant! It's such a pleasure to have such keen and knowledgable folks offer their help when needed. The sketch for the stainless steel rope cleats is now on its way!

Thanks again, Regards, JustBaffled.