Hello I m new here and new with using inkscape.
I ve got a problem and don't know how to solve.

I need to draw a circle, what I already did, and add more (360) nodes in a uniform distance. How can I do this? I already tried the "add node" effect but that doesn't work.

Can somebody help me?

Thank you!

Welcome aboard!

You better draw a poligon with the right node number and turn that to a circle than add nodes to a circle drawn by four nodes, the result will be more accurate.
Press * on the keyboard to chose the star tool,
set it to poligon, and draw one as you would use the ellipse tool to draw a circle.
Set the number of nodes to 360.
Then, press Shift+Ctrl+C to convert path from that object, select all the nodes with the node editor tool, and make nodes rounded.

Good luck!

Hi.

Why would the circle method be less accurate than the Star or Polygon method?

RGDS
Ragnar

http://www.inkscapeforum.com/viewtopic.php?f=28&t=13427&p=52055#p52080
It is hard to guess when talking on accuracy, as the measures can be inaccurate too, but
here is an example svg how to check it:


There is a red circle at the background, above is a poligon.
Both center aligned.
When zoomed in, you can see about 0,02 pixels inaccuracy on a 600 pixel wide circle.
Then, to decide which isn't accurate, there is a center aligned pointer of the same diameter size, which is rotated to each nodes of that polygon.
Based on that, the more nodes it has, the more accurate the circle is.

Hi.

I did the same test but set the spoke ratio to one and 512 nodes on the polygon to get the same number of nodes as on a circle.
I converted the circle to nodes and selected all (4) nodes, then added nodes seven times ( 4 * (2^7) = 512 ).
The stroke of the two objects match even when zoomed in to the max (25600%).

RGDS
Ragnar

Then look at this one:
The circle is drawn now with dark red and 512 nodes.
The light blue polygon has 512 nodes too, center aligned to the circle, and both are turned to a path.
As the diameter is an enermous 100000 pixel large, the inaccuracy pointed out is 13,406 pixel big.
https://dl.dropbox.com/s/6s6azmyw2g8kvce/crc2.svg

Surprisingly the error ration got bigger too:
with such ration, at a 600 pixel wide circle the inaccuracy would be (13,406/100000)*600=0,08 pixel big.

Hi

I see your circle and your polygon and the mis-match of 13.406 pixels.

For all practical purposes the two are identical? Or is it "something" that I don't get?
Where would you "need" the improved accuracy of the polygon?

RGDS Ragnar

The svg was zoomed to a part with inaccuracy. It is about at 1 o'clock.
By rectangle select you can find it.
For the practical purposes.
The mentioned 360 nodes couldn't be achieved by adding 2^n nodes to the circle.
Hard to tell more.
For that torus cut section I was working a while ago, I constructed plenty of nodes on each section, with avoiding the inaccuracy from booleans by using the snap function only.
Then, when wanted to "rephrase" them by adding new points where it had exact tangents, the points didn't got organised in a nice pattern.
Not really sure what produced that result, but small mistakes can add up alike.
Maybe it was just that I didn't experimented enough with the devbulid's tangent lpe.

Yes, I've asked Lazur about this before. There is a very, very slight discrepancy. But not knowing the purpose which cassiopeia needs this, it may not be necessary. However, it IS a really fast way to accomplish the goal, and with the bonus of more precise circle

cassiopeia wrote:I need to draw a circle, what I already did, and add more (360) nodes in a uniform distance.

ragstian wrote:Why would the circle method be less accurate than the Star or Polygon method?

HI Ragnar, this is just my opinion, but when I saw the original post and Lazur's answer, I thought of the add nodes extension but I came to the conclusion that the simplest way to end up with a specified number of nodes is to use his polygon method. Clicking the add nodes button only doubles the number of nodes each time, and the add nodes extension (extensions>modify path>add nodes), will do the right thing - if you use the # of segments option and enter 90 (because you are starting with four segments, In My Opinion) please ! Note! that your results may be off by a lot as a result of one node having many duplicates on it. This is fixable, but Lazur's method is easier.
The reason to use the extension is that you may already have your circle drawn and in place, or you may want to use an arc and not the whole circle. And in general you might just want to learn to use this extension - This has been my opinion. Be thankful it's not yours.

Hi.

I need to draw a circle, what I already did, and add more (360) nodes in a uniform distance. How can I do this? I already tried the "add node" effect but that doesn't work.

But - there's an easier way to make a "compass" scale - use Tiled Clones from the "Edit - Clone" dropdown menu.
Far easier - and (maybe) more accurate. (Leave this to Lazur URH - he will check it out and report any discrepancies! )

To make a simple compass scale - first enable snap to "everything".

1. Drag two guides to center of page (canvas in Inkscape lingo) - one horizontal and one vertical.
2. Draw a circle covering most of the width of the canvas - point to the cross of the guides and hold down Ctrl + Shift keys to start at center and make a circle (not an ellipsis)
3. Draw a short straight line along one of the guides across the circle - ( enable snap to guide first).
4. Select the short line. by clicking on it once, wait a little and click once more - a small cross will appear in the middle of the line, the cross is the "rotation handle" of the line.
5. Click the rotation handle and drag it to the center of the drawing where it will snap to the intersection of the two guide lines.
6. Go to Edit - Clone - Create Tiled Clones (TC).
7. Click Reset to reset all TC settings.
Enter in Main dialog:

Row, Columns 1 x 360.
Enter in the different tabs as follows:

Symmetry Tab: P1; simple translation
Shift Tab: Per Column -100% (Minus 100 - The minus sign is important.)
Rotation Tab: Angle 1° Per Row, 1° Per Column.
Click apply - If everything went according to plan - You have a 360° Round scale.

To modify to make the appearance better; instead of the simple line make a wedge - make every 5 and/or 10 degree marker longer etc.
Lots of room for experimentation. In the image below - note the small line at the top looks "fatter' than the rest - shows the last clone to be on top of the "original". By selecting the "original - (hold down theAltkey while clicking to select a object under another ) - any changes to the original will "happen" to all clones as well.

Rightclick Image to download SVG:



Good Luck
RGDS
Ragnar

How about this one:
1. Draw a polygon with the star tool of 360 nodes, convert it to path by pressing Shift+Ctrl+C
2. Duplicate it by pressing Ctrl+D, scale it down by pressing Shift -and Ctrl, if width/height ration is not linked together
3. Select both paths and run the extrude path extension.

Hi Lazur URH

That's just too simple!!
To get 360 "tics" I had to specify 180 spokes?

RGDS
Ragnar

You could specify only 180 spokes for the tiled clone method,
without the need of any guide lines.
Drawing a vertical line while holding down Ctrl, duplicated it and moved down to position below by arrows or holding down Ctrl,
selecting it and the original, combining it -and you have an object that will have to be cloned for only 180 times.
But that previous method with the star tool is faster.

Somewhere we have moved from adding nodes to adding tick marks! Unless I missed the OP's request, but anyway these diversions are often informative for future searches of the forum.
This is my addition - use the LPE 'ruler' to add ticks to the circle.To get an exact number though you will have to do - math . Find the circumference of the circle in pixels and divide by 360; enter that in the mark distance field... sure it seems inaccurate because of the pi calculation, but that inaccuracy is going to be present in every method even if it seems otherwise. I believe the ruler LPE is standard.

Hi.

Somewhere we have moved from adding nodes to adding tick marks! Unless I missed the OP's request, but anyway these diversions are often informative for future searches of the forum.

Sorry - that's my fault getting the thread "off track". I just saw the 360 - and added two and two.

RGDS
Ragnar

COMMENT for thought: Am I hearing a need for creating a circle (or square, etc) then having the ability to specify the number of nodes without using the add nodes function? Could that be coded easily? I'm envisioning an extension where you simply type the number of nodes into a box. Is that even practical, because it sure would be nice to have.
BTW, why isn't there an align function that works specifically on circles.....
I had a similar problem the other night and making a perfect, large, evenly spaced circle started to drive me insane....
(Ragnar, do I forsee this as a June project? - just kidding BTW! Maybe I should stop thinking, lol).

Yes, an add node to a curve's points with defined tangents would be great...
-as there is an extension of add nodes in the modify path menu already.

ragstian wrote:Hi.

Somewhere we have moved from adding nodes to adding tick marks! Unless I missed the OP's request, but anyway these diversions are often informative for future searches of the forum.

Sorry - that's my fault getting the thread "off track". I just saw the 360 - and added two and two.

RGDS
Ragnar

With that "cassiopeia" name it is possibly for a star map.

another new user to inkscape. previous corel 3 through to v.7
it's been awhile.
was struggling with deforming a perfect circle
this is an immense help.
thank you gentlemen