I request more CAD-like features

Flesh out your ideas for new or improved Inkscape features before submitting a request.
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ragstian
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Re: I request more CAD-like features

Postby ragstian » Fri Feb 01, 2013 5:05 am

Hi druban

Great. I know everything in the book about getting the memory confused. Glad I'am not the only one :D .
As you might have seen from some of my earlier post I "love" the parametric plot function in Inkscape. http://www.inkscapeforum.com/viewtopic.php?f=6&t=12946
Just had to make the Fibonacci spiral using Parametric curves;

Image
Click image for larger version.

Cut and paste into Inkscape to avoid typing errors;
x Function; pow(((1+sqrt(5))/2),2*t/pi)*cos(t)
y Function; pow(((1+sqrt(5))/2),2*t/pi)*sin(t)

Next challenge - as I like the tiled clones as well; make - and position - the rectangles in your example using tiled clones.
( Have some "brain-problems" with this one - Lack of CPU power - brain pre-dates the Intel 4004 era by a "few" decades!)
http://www.intel.com/content/dam/www/pu ... poster.pdf

Have fun
RGDS
Ragnar
Good Luck!
( ͡° ͜ʖ ͡°)
RGDS
Ragnar

Lazur
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Re: I request more CAD-like features

Postby Lazur » Mon Feb 11, 2013 5:21 pm

Here are three aproximations of that Fibonacci spiral I just created, click on it to enlarge:
Image

Because the circles are not accurate, just use the polygon, with the curves made rounded -cad uses the same method.
On the image posted 48points were used per "circles".


On this image all three are put together, to make the difference legible (click to enlarge):
Image
The approximations are in the red-green-blue order, blue is the finest.
The vanishing point is aligned in the center of the image.
Note, that manually you cannot draw an accurate spiral, just approximations.

Personally I'm fine without the cad-like features, could get used to manual drawing quickly.
AND something, that is better handled in inkscape than in autocad is small errors.
You get inconsistency and boolean effect errors very often, while inkscape just simply merges points close to eachother.

Will post my five cents for golden-proportions-rectangle drawing on the tutorial section later on, it's pretty simple.

Lazur
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Re: I request more CAD-like features

Postby Lazur » Tue Feb 12, 2013 11:09 am

Here is the tutorial for a possible geometrical construction of a golden-proportions-rectangle:
http://www.inkscapeforum.com/viewtopic.php?f=6&t=13518&p=52070#p52070

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brynn
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Re: I request more CAD-like features

Postby brynn » Tue Feb 12, 2013 9:48 pm

Because the circles are not accurate, just use the polygon, with the curves made rounded -cad uses the same method.
On the image posted 48points were used per "circles".

Why, or how, are circles not accurate?

Lazur
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Re: I request more CAD-like features

Postby Lazur » Tue Feb 12, 2013 10:38 pm

brynn wrote:
Because the circles are not accurate, just use the polygon, with the curves made rounded -cad uses the same method.
On the image posted 48points were used per "circles".

Why, or how, are circles not accurate?


SVG Image

Around the path the distance from the origo differs. Only controlpoints are calculated precisely. Zoom in and you will see it.

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brynn
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Re: I request more CAD-like features

Postby brynn » Fri Feb 15, 2013 8:43 am

Well, I do see an approx 0.05 px space beteen the tip of the blue spikey thing and the circle, around 4:30 (and 7:30, 10:30, and 2:30) which is 0 at 3:00 (6:00, 9:00, 12:00). You have to zoom as far as Inkscape can zoom (25,600%) to see it. But how do I know whether the circle is not perfect or the spikey thing is not perfect?. How was spikey thing made -- Star tool? Did the circle go out of whack when converted to path, or was it distorted as a shape? If the circle isn't perfect, how can the angles and arcs and wedges (segments), which are made from circles, be correct? Is 0.05 pixel worth worrying about? If Inkscape were a CAD program, yes. But it's not....

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ragstian
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Re: I request more CAD-like features

Postby ragstian » Fri Feb 15, 2013 11:49 am

Hi brynn

If the circle isn't perfect, how can the angles and arcs and wedges (segments), which are made from circles, be correct?

I follow your logic but the circle are made as a bezier curve, a bezier curve with four nodes can never represent a true circle.
See here; http://www.tinaja.com/glib/ellipse4.pdf

For (most) all practical purposes in Inkscape the approximation is good enough?

RGDS
Ragnar
Good Luck!
( ͡° ͜ʖ ͡°)
RGDS
Ragnar

Lazur
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Re: I request more CAD-like features

Postby Lazur » Fri Feb 15, 2013 12:25 pm

brynn wrote:Well, I do see an approx 0.05 px space beteen the tip of the blue spikey thing and the circle, around 4:30 (and 7:30, 10:30, and 2:30) which is 0 at 3:00 (6:00, 9:00, 12:00). You have to zoom as far as Inkscape can zoom (25,600%) to see it. But how do I know whether the circle is not perfect or the spikey thing is not perfect?. How was spikey thing made -- Star tool? Did the circle go out of whack when converted to path, or was it distorted as a shape? If the circle isn't perfect, how can the angles and arcs and wedges (segments), which are made from circles, be correct? Is 0.05 pixel worth worrying about? If Inkscape were a CAD program, yes. But it's not....


Yes, it was made with the * tool. You can be sure about the accuracy if the object can fit when you duplicate and rotate it. Poligon and star nodes are counted precisely that way.

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brynn
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Re: I request more CAD-like features

Postby brynn » Sat Feb 16, 2013 3:31 pm

Aw, you're breaking my happy, precise Inkscape bubble!

navidoo
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Re: I request more CAD-like features

Postby navidoo » Sun Oct 06, 2013 4:02 am

ragstian wrote:5. Rotate the rectangle until it snaps to the line. (Midpoint of the short end of the rectangle will snap to the line - one side of the rectangle will then be perpendicular to the


This step doesn't work for me. The midpoint of the rectangle's side doesn't snap to the line. I have version 0.48 and all the snap button in the toolbar are selected except for snap to grid. Any idea why?

Lazur
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Re: I request more CAD-like features

Postby Lazur » Sun Oct 06, 2013 8:11 am

Have no idea why snapping doesn't work.

Here is how I would construct the origo of the circle:

SVG Image

Duplicate the original triangle twice, adjust their nodes so each side's midpoint will become the centre of their bounding box,
then rotate each with 90° and scale proportionally until they are crossing.

paul59539
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Re: I request more CAD-like features

Postby paul59539 » Sun Dec 22, 2013 8:54 am

It'd be great to finally have a way to invert the coordinates system. Also proper command line options. Also Being able to manipulate centers of rotation like objects.

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microUgly
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Re: I request more CAD-like features

Postby microUgly » Sun Dec 22, 2013 2:33 pm

paul59539 wrote:Also Being able to manipulate centers of rotation like objects.

For reference, you can do this already.


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