I hereby declare myself a super-fan of the open source graphics editor, Inkscape. You should be, too. “I, Inkscapist” is a (new) series of articles I’m planning to write about getting your feet wet as an artist considering dabbling with this sweet vector design package. I’ve got no formal association with Inkscape, but contributing to open source doesn’t always mean writing code: someone needs to evangelize and educate, too. Share & enjoy…
Three Curves You Should Know
I wanted to start simple. I am assuming that you, my art-minded and uber-creative audience, has never really considered what a vector art suite can do for you. You should. Where many folks tend to think learning Photoshop is the ultimate art-creation skill — and it is powerful, make no mistake — pure vector design is that ace in your art tool-kit that once you master you’ll find yourself gravitating to more and more. Inkscape is one of many such software… with the added advantage that it’s awesome and it’s free.
Now here’s the thing… some part of me vaguely recalls the art courses I took waaaaay back and how one of the first things you learn is the fundamental shapes of things. You learn to combine circles and square and other foundational forms into move complex images. I recall standing at an easel with a big blank sheet of paper and some charcoal and literally drawing swirls and swirls and more freely-flowing swirls.
Nodes and curves are one of those foundational objects in vector art. Nearly everything you will eventually draw in Inkscape is a set of various nodes (points) on a canvas that connect to each other via the various curves (arcs and lines.) These have big, fancy names, but to the noob it really just needs to be understood that the three major types you’ll work with are corner, smooth and symmetric.
Corner is probably the easiest to explain. A corner node acts as a kind of sharp edge on the curve where it resides. Think of it as making a kink in the curve that can be manipulated by the handles. The corner node is represented by a diamond shape, and the handles by the highlighted lines and circles that appear when you select it. The curve on each side of the corner node basically ignores what is happening on the other side resulting in just what you might expect: a sharp or not-so-sharp corner at the location of the node which is useful for the various pieces of hard, angled shapes.
Smooth (and auto-smoothed)
Smooth nodes are represented by square-shaped nodes, and can be manipulated in a nearly identical way… with the exception that the curve on either side of the node reacts and changes based on the it’s opposite side counterpart. The computer attempts to avoid a kinked corner here, and instead generates a rounded, uninterrupted arc whose shape is determined by the length and angle of the associated handles. You’ll might notice that the handles always form a straight line that runs tangential to the curve and the shape of the node is determined by where on this line the node lives. This node is very useful for creating freely flowing, rounded segments and shapes.
Symmetric nodes seem to me to be a kind of off-shoot of the smooth node. Symmetric nodes not only pay attention to what the arc on the other side of the node is doing, but it mimics-slash-mirrors it so that the resulting curve is a smooth arc with the mid-point being the node. You’ll also notice that (like the smooth curve) the handles form a straight line that runs tangential to the curve but who’s exact mid-point is the node… but maybe that’s too much math-ish stuff for this post. (To be honest, I rarely deliberately employ this one, but I’m sure if you are looking to make precise art or design it would be very useful.)
Once you’ve downloaded and installed Inkscape, and then familiarized yourself with the basic controls (maybe I’ll cover that in a future post)… give it a try. Your homework is to make a simple drawing that uses all of these three types of curves and nodes. My own quick-and-dirty example is attached. Can you spot them all?
Have something you’d like explained about vector art? I’ll try my best: leave a comment. Screens, art, and information is all based on my own personal use and experience with Inkscape, the open source vector graphics editor.