how to make perfect round with node tool ?

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kakku
Posts: 6
Joined: Mon Aug 03, 2009 3:02 am

how to make perfect round with node tool ?

Postby kakku » Mon Aug 03, 2009 4:13 am

hi, i'm in need of some help. after googling and not finding it i decided to ask here.

i draw my path with the pen tool and then i use the node tool to make certain parts round.
all my curves need to be perfect round. like parts of a circle.
i'm using inkscape to design levels for a game so i need them to be perfect round or my physics will screw up.
so i first draw a 45 degree diagonal, and then i drag handles.
first i thought that if i put the node handles halfway(see blue arrows in example), it would make a part of a circle (seems logical in my mind)
but this seems not to be the case.

is there a way to snap to the perfect circle roundness ?
or maybe a way to put the handles on the right place with some input coordinates ?
or maybe i have to add a point in the middle and drag that instead ?

please help >.<
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SureWhyNot
Posts: 137
Joined: Mon Jun 16, 2008 11:37 pm
Location: United States

Re: how to make perfect round with node tool ?

Postby SureWhyNot » Mon Aug 03, 2009 6:34 am

The spiro function in the development builds could be what you're looking for. Give it a try.

kakku
Posts: 6
Joined: Mon Aug 03, 2009 3:02 am

Re: how to make perfect round with node tool ?

Postby kakku » Mon Aug 03, 2009 8:22 am

thanks for the reply, and spiro looks real sweet.
but :( i'm on a mac..

i found this though.. : http://www.whizkidtech.redprince.net/bezier/circle/
it helps a little.

~suv
Posts: 2272
Joined: Sun May 10, 2009 2:07 am

Re: how to make perfect round with node tool ?

Postby ~suv » Mon Aug 03, 2009 9:14 am

1) Inkscape 0.47pre1-2 LEOPARD from http://sourceforge.net/projects/inkscape/files/ is the latest build for OS X 10.5.7

2) Why use the pen tool for arcs if you have an arc tool within the ellipse tool?
select the :tool_ellipse: , draw a circle (with 'Ctrl') and now - with the :tool_ellipse: still selected - hover over the 3 visible nodes of the circle and read the hints in the status line: you can position the start and end point of the circle to create a segment, and with the toggle on the ellipse controls bar you can determine if it's a segment (closed, filled path including the center) or an arc (unclosed shape).

hth, ~suv

kakku
Posts: 6
Joined: Mon Aug 03, 2009 3:02 am

Re: how to make perfect round with node tool ?

Postby kakku » Mon Aug 03, 2009 9:07 pm

thanks a lot! the :tool_ellipse:-tool is pretty neat with the ctrl-key pressed :)

one additional question:
once i have my path closed is there a way to flip the other of the nodes from clockwise to counterclockwise ?

~suv
Posts: 2272
Joined: Sun May 10, 2009 2:07 am

Re: how to make perfect round with node tool ?

Postby ~suv » Mon Aug 03, 2009 10:35 pm

testing while typing :

- Did you try to use 'Path > Reverse'?
oops - no, that works only with paths, not with ellipses.

- or mirror the ellipse before adjusting the segment start and end points?
this should work.

kakku
Posts: 6
Joined: Mon Aug 03, 2009 3:02 am

Re: how to make perfect round with node tool ?

Postby kakku » Mon Aug 03, 2009 11:29 pm

'path > reverse' works !
i do make closed paths of them.

thanks again, your help is much appreciated.

and if you don't mind if i borrow some more of you inkscape-wisdom, could you tell me if there is another (easier) way to set the first point of a path, besides going into the xml-editor and copy-pasting the right node to the front of the line ?
if my paths have no curves in it, its simply a matter of rearranging the nodes, but when there are curves involved that is not a option..
this is not a real issue(i could live without it), but it would be very practical, because in some situations i need to know/choose which node is the first for reasons to do with my game physics. that's why i initially started with the bezier tool.

~suv
Posts: 2272
Joined: Sun May 10, 2009 2:07 am

Re: how to make perfect round with node tool ?

Postby ~suv » Mon Aug 03, 2009 11:47 pm

kakku wrote:and if you don't mind if i borrow some more of you inkscape-wisdom, could you tell me if there is another (easier) way to set the first point of a path, besides going into the xml-editor and copy-pasting the right node to the front of the line ?
if my paths have no curves in it, its simply a matter of rearranging the nodes, but when there are curves involved that is not a option..

I don't have _that_ much practical experience either ;-). To add a straight line at the beginning of an (arc converted to path), I'd draw the straight segment with the bezier tool, then select the line and the arc and apply 'Path > Combine'. Otherwise I'd experiment with the functions of the Node Tool Controls Bar, where you can add, insert and delete nodes and segments.

And - first of all - I'd have to read the manual page about path-editing myself… ;-)

hth, ~suv

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prkos
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Location: Croatia

Re: how to make perfect round with node tool ?

Postby prkos » Tue Aug 04, 2009 1:38 am

You can select the node you want to be the first, then add the next node to selection, break the curve there, then select them again and rejoin, but you won't get the same curve between those two. Then probably the best idea is to add a node that's very close the one you want to be the first (after it that is) and do the procedure there.
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