Feature Request: New Vector drawing mode "Spiro"

[remi]

No matter, how the Inkscape team is trying to solve the problems with Spiros. You could go your own way.

Or if that's not acceptable, the C4 points could be converted to beziers (that's what libSpiro does) as soon as any transform is applied that would give non-affine results.

Well, it doesn't sound like a good idea to make such a conversion permanent and automatic. So it's better to make it on the rendering stage dynamically.
It is also probably simpler to implement this as a separate class.

It seems to be a clever idea to use the Spiro mode as a simple input mode and convert all Spiros internally to Beziers (that's the whole point of libspiro). With this way all transformations could be handled with the normal algorithms:

• If the user creates a path with Spiro points, the path is internally converted to Splines. The interface shows the generated Spline together with his Spiro points.
• Whenever the user starts a transformation, the normal algorithms for Splines are used for this.
• At the end of such a method, there is only one additional step to do: Calculate the resulting Spiro points starting from the transformed Bezier path. It's simply the reverse operation of the normal Spiro algorithm.
• The only difference between a normal path and a Spiro path is, that the Spiro mode/tool is calculating, storing and showing the new Spiro points after such a transformation.

Remi

[covoxer]

Yes Remi, generally you are right. One point though:

At the end of such a method, there is only one additional step to do: Calculate the resulting Spiro points starting from the transformed Bezier path. It's simply the reverse operation of the normal Spiro algorithm.

I see no need in such a reverse operation. If I get you right, you need this only to apply transformations to the Spiro control points. But this can be done staight forward. The shape is rendered as matrix transformed bezier, and control points are simply transformed prior to rendering.
So it's even simpler.

[wizard509]

That video won't play on any of my players. Not Windows media player, not Quicktime player, not Camtasia player!
- Andy

I had that trouble too! Plays fine with VLC media player.

I really like the Spiros tool, I want it too!

[remi]

I see no need in such a reverse operation. If I get you right, you need this only to apply transformations to the Spiro control points. But this can be done staight forward. The shape is rendered as matrix transformed bezier, and control points are simply transformed prior to rendering.
So it's even simpler.

Sounds good, but I'm not sure, if the Spiro control points have to be recalculated (set at a new position, not only transformed) after you scale a Shape with Spiro points in only one direction.

Remi

[JokeArtist]

Any ... I mean ANY new vector tools are appreciated.

Remi I appreciate the way that you are dicussing to find solutions to get something like this implimented - rather than, it can't be done because this this and this.

[remi]

Interesting: We as Xara Xtreme users would love to see a "Spiro" tool, like the next Inkscape Version is offering and the Inkscape users have asked for a Xara Xtreme node type.
From the Release Notes of Inkscape V.047:

Auto smooth nodes: a new "auto" node type was added, similar to the one Xara Xtreme has. An auto node is a smooth node which automatically adjusts (rotates and stretches) its handles when this node or its neighbors are moved. This adjustment (same as what you get when you convert node type to Smooth, but continuous) keeps the curve at this node as smooth as possible. It feels a bit like Spiro paths (see below); although not as smooth as a Spiro, auto nodes may often be preferable as they work without applying any Path Effect. Whenever you manually adjust the handles of an auto node or drag the adjacent curve, it loses its auto state and becomes simply smooth; for this reason, it is recommended to edit smooth nodes with the node handles hidden via a toggle button on the controls bar. Auto nodes are represented by little circles, as opposed to smooth/symmetric nodes (squares) and cusp nodes (diamonds). To convert selected node(s) to auto, press Shift+A or use the corresponding node type button on the controls bar.

The only difference between the Inkscape and the Xara Xtreme community seems to be, that they really get, what they crave...

Remi

[abligh]

Re Covoxers point:

Yes and no. Most but not all objects in Xtreme get translated by simple transformation of matrices. A good example of ones that don't (under certain circumstances) are rounded corners of rectangles. This shows that is possible within Xtreme to have objects which can be transformed in a non-trivial manner.

It would hence be possible to have objects which (like the shape tool objects) are translated at render time into Bezier paths, but when transformed by matrix in the program (e.g. sheared and stretched in the selector tool) behave differently. So, yes, if you stretched a circle you would not necessarily get the ellipse you might expect, just like if you stretch a rounded cornered rectangle the rounded corners don't stretch. If you want this behaviour, you could do "Make Shapes" on it.

So it's possible. Whether it would be (a) intuitive or (b) desirable is another issue.

[Hewitt David]

Sorry for my belated input but i was put on a 7 day time-out and was just never re-instated (thanks for that) and just had to register again (i'll probably just disappear...anyway)...
Alot of what needs to be said has already been said i guess but here's my spin/perspective on it...

Firstly it has to be said that this is a very nice algorithm....
What seems to have miffed a few posters there is that when you put only a few nodes down (like in some of the cases presented in the video) the spiro path does not in at all in any way really match up to the nodes digitized ETC.....

And while it is true that the current node editor tool in xara would better conform in these circumstances this current tool seems to be optimised for more general use and is no where near as good at doing those perfect smooth grapical curves that perfectionists and graphic designers often need to do....So for these people its going to be like "Spiro to the rescue"......

This spiro math will suit alot of perfectionist and graphic designers out ther that are frustrated at how difficult it can be in some instances currently when they are trying to get a perfectly smooth curve with the current node editor tool. So altough it is not as practical in some general situations it is fantastic for graphical work where smoothness is paramount.

Some of these paths in the video only have a few nodes and this is to illustrate how spiro works as it becomes increasingly obvious exactly how spiro works the less nodes there are....

But bare in mind people that with any "curve node input method" (IE with no bezier handles ETC) that the more points you put down the better this type of thing will conform to the desired path....

But as the spiro math is totally different then what is currently in Xara's node editor tool and of course it is going to behave differently and have a learning curve (no pun intended) associated with it, like anything.


This is just another Algorithm that is plainly very powerful... infact quite amazing.
But again like anything its not for everyone...and will be suited more to some types of work than others, Weather or not you like it or not will depend on what type of work your doing.

One thing is for certain however... alot of people are going to love this...
And i think its great that inkscape is "bringing it on!".

We need rivalry like this...i love it.

Inkscape is the perfect counter weight to keep Xara on their toes.

P.S i like the preset node reduction capability too: i only just finished making this very same suggestion...
(And got scolded by two posters for putting up: "tired un-inpspired ideas" and ideas that are "impractical" from a real world programming perspective...i wonder if they will now rave on about the same idea now that inkscape has implemented it in their latest release.... Tis ok no need to appologise or anything...we all get carried away at times myself more than most ......)