Regular spirals

Index

It would be hard to say that we are used to a drawing system by now, but in a way, yes, it is possible to get used to the attitudes or at least the on-screen requirements for Bézier manipulating (and taming) curves in order to achieve an imagined result.

Considering the examples of drawing methods we discussed so far, we know that first anchoring points are placed, and then by adjusting the control handles, the spline passing through the anchor point is dealt with. The expected attitude is one of semi-fluidity. A direction is given to the line, and we just need to adjust its swiftness and acuteness.

Drawing an S in Inkscape. Left showing the one using Bézier curves and right the Spiro version

How about something different though? Why must we assume that, if no overwriting properties are applied, a line that connects two anchor points, is actually straight? According to Raph Levien, this does not have to be the case. Spiro, the toolkit for curve design that he developed, starts from a totally different set of presumptions and expectations.

When drawing with Spiro, all of your lines are curved. Simply put, the structure of the line description is based on a mathematical constant. This constant describes a regular spiral. Anchor points on a Spiro curve pinpoint two locations on the progression of the spiral, be it spiraling positively, or negatively (we could say, spiraling inwards and outwards or bigger and smaller). The anchors can be attributed attitudes, not dissimilar to Bézier, but working in a totally different frame. While your control handles can influence growth or size of the spiral (your line), it retains it's curved nature.

The result is one of organicity, of fluidity, or even maybe a certain regularity. The lettershape 'S' is a useful example of a situation where you would like the curve you're drawing to understand that, by nature, it spirals, it curls, it curves and swerves. Giving an upright and proper attitude to an S lettershape is really helped by the functions of Spiro, which gives us situations of lesser amounts of control points for a shape that typically is very hard to get right.

In the 2007 post to Typophile, Raph Levien1 wrote:

Because I'm starting at Google in a couple weeks, I won't be beating the bushes myself to push this technology out into the world. To a large extent, I'm "throwing the technology over the fence".2


  1. Raph Levien http://levien.com/phd/phd.html 

  2. Raph Levien, Spiro 0.01 release (2007) http://www.typophile.com/node/33531