Author Topic: angle specification in minutes  (Read 165 times)

July 12, 2018, 05:39:42 AM
Read 165 times

Pijar

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Is there a way to specify angle in minutes? It is possible to do so in degrees and decimal parts of degrees down to one thousandth, but degree system was supposed to be sexgesimal, not decimal. I need a guide tilted 20 minutes to horizontal. I know that 0.333 degrees will do the trick pretty decently, but I would prefer to have it the exact and more proper way.
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July 12, 2018, 06:44:37 AM
Reply #1

brynn

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Welcome to the forum!

I probably can't answer that in any satisfying way for you.  But I see that there are 3 other choices of units, besides degrees.  I don't know math well enough to understand them.  (Hah!  Or more precisely, I don't remember math well enough.)  But I wonder if any of them can be converted.  Well I mean, I wonder if the minutes can be converted to any of them?

I don't know of any way to add minutes to the menu, except it's probably by hard coding the program.  If you happen to know the right code, I'm sure developers can help you with whatever you need.

I searched new feature requests, but the only reference to "minutes" was about time and not angles.  So you certainly could make a feature request about that.  But who knows how long it would take for that to happen - if it would happen at all.

So as for now, I don't really know any way to accomplish angles measured in minutes.

Maybe someone else will post with a more hopeful reply for you.  That's all I know or can quickly learn about it.

Oh....  Well I thought of something, but it's still not really what you want.  You can increase the number of digits after the decimal point, which gets you incrementally closer.  But for one third - I do remember enough math that you just never get there (using decimals).  It's .3333 infinitely.

Wish I could be more helpful.
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July 12, 2018, 12:09:00 PM
Reply #2

Lazur

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Quick and easy hack is by using the * tool. 0° 30' is 1/1080 full turn, so a polygon with 1080 spikes would be theoretically perfect.

Other less elegant but quite accurate method is drawing a circular arc with the ellipse tool, converting it to a path, then using the extension/modify path/add nodes/by number of segments/3. Theoretically it's not exact as the extension uses cubicsuperpath (as far as I understand, approximates the Bézier spline with a mathematical formula).

Not sure how to compile inkscape to have those hard-wired spinboxes extended but probably it's an easy fix for whoever did that once.

Other solutions between the hacky and the neat one is by using extensions.

First, there is the extension/render/grids/polar grid.
The spinbox is limited to 1000 angular divisions, but you can easily edit the corresponding part in the inkscape/share/extensions/...polar grid.py-or inx -writing from memory, have to look it up.

Then there is the function plotter and parametric curves extension.

If you plot a circle from 0 to 1/1080, it should draw the node at the exact location -the same where the *-tool would draw...

All in all if that's for a quick construction I'd draw it with the * tool.

July 13, 2018, 05:21:54 PM
Reply #3

Moini

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You can also enter any simple calculations into the number boxes, if that helps. Just use * / + and - as you would when you type the formula into a calculator.