74 Technique

Computer Arts June 2008

Illustrator

Mastering Bézier curves

Used properly, the Bézier-curving Pen tool in Illustrator is extremely powerful and versatile. Ben the Illustrator shows you how to get the most out of it From furniture to album sleeves, few would argue that the 1960s bore witness to some classic designs. It was also the decade when the Bézier curve came to prominence, as employed by the French mechanical engineer Pierre Bézier. The Pen tool’s use of Bézier curves makes it one of the most valuable features of Adobe Illustrator, and it can create beautifully fl owing lines, perfectly realistic shapes and super-fresh graphics. However, Bézier curves can be diffi cult to get to grips with, and it’s easy to pick up bad habits on the journey to understanding how they work. This tutorial goes back to basics and focuses on the simplest methods and best practice for their use, before moving on to cover more advanced techniques and effects.

Ben O’Brien Also known as Ben O’Brien, Ben the Illustrator creates ethereal, super-colourful landscapes for art prints, exhibitions and commercial commissions. Clients include smart, the Guardian, House & Garden and Vice Magazine. Find out more at www.bentheillustrator.com and www.speakerdog.com.

On the disc The Illustrator fi le for the fi nal image can be found in Disc Contents\Resources\curves.

Time needed 2 hours

Skills Create perfect

curves easily and effi ciently

Customise standard shapes and lettering

Develop a line into a realistic object

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Computer Arts June 2008

75

01 Prepare what you’re going to create, whether it’s something freehand and unplanned, or a photo or drawing to trace. This tutorial is equally useful whether you’re creating text, illustrations or purely graphic shapes. I’m using a rough sketch, with some curves that really need perfecting with Illustrator’s tools.

06 You get more control if you create curves composed of a few shorter sections, instead of letting the Bézier function create an entire curve in one go. When you have created this curve deselect the object. To adjust the curve, select an anchor point using the Direct Selection tool or create new anchor points, and drag the Bézier handles as required.

05 Release the mouse button and click further along the intended curve. The curve is created automatically, fl owing on from your previous path. You can either keep it as given, or drag the Pen tool to control the curve yourself. If the curve is not forming as required, try clicking and dragging on different points of the intended curve.

04 To create a basic curve using the Pen tool, click once at the start point of your intended curve, then click and hold down at the end point to create a straight line. Now drag to see the curve forming as you drag the Bézier handles. Drag in different directions to get used to how the curves form in the opposite direction to your movement.

03 Along with the regular Pen tool, there are three other Pen tools to use: the Add Anchor Point tool, the Delete Anchor Point tool and the Convert Anchor Point tool. Use the last of these to change a Bézier curve into a straight line, or take a corner formed by two straight lines and make a curve by dragging from the corner anchor point.

02 The ends of any path have anchor points, and any curved path also has draggable Bézier handles. The angle at which you drag the Bézier handle away from the anchor point determines the curve direction; the further you drag the handle, the more extreme the curve. If an anchor point has a fi lled-in box then it’s selected and active.

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76 Technique

Computer Arts June 2008 www.computerarts.co.uk

11 You can add anchor points to this shape enabling you to create the object you want, perhaps while keeping some areas as perfect curves. Here I have created a loop in my rainbow, with the top being a perfect semi-circle. You should now be able to create beautifully simple or incredibly complex lines and shapes with full control.

09 By clicking the fi rst anchor point again while the lines are still selected, you can make a solid object. This happens with a straight line as well as a curve. Alternatively, select the two end points and use Object>Path>Join to join them with a straight line.

08 To create a series of curves that don’t fl ow together but are joined as one object, make the fi rst curve as usual, then using the Pen tool deselect the end anchor point (making its box empty and losing the Bézier handles) and create a second curve.

10 It’s often useful to take a standard shape and amend the Bézier curves yourself. Create a circle using the Shape tool, then click on one of the anchor points with the Convert Anchor Point tool, making that anchor point into a corner. Drag the anchor point or the Bézier handles, or use the Scissors tool to separate the two lines at that point.

07 Duplicate your completed line, then use the Direct Selection tool to adjust the Bézier handles to create slight variations on the original curve. This is great when you require lines that differ but fl ow together, such as for rainbows, ribbon or hair.

Filling in your line work When you’ve created perfectly fl owing curves, make sure you get the fi ll colours exactly right. Create subtle fades, experiment with transparency and take the time to select the right tones if you want to provide a beautiful fi nish for your vector art. Don’t forget, too, that losing heavy outlines adds an element of realism to an object. Bézier curves are a blessing to competent Illustrator users, so don’t waste what they can give you.

15 With your lettering still selected, choose Object>CompoundPath>Release to give you a group of letters broken down into basic paths. You can now go wild using the techniques outlined here. I’ve made the fairly angular Futura Black into the basis of a curvier, refreshingly bubbly font.

14 Bézier curves are equally useful for customising type. Type some text, select the body of text with the Selection tool and choose Type>CreateOutlines. This changes your font into a group of compound paths.

13 Select your thick line and use Object>Path>OutlineStroke to make it into a fi lled object. You’ll see that the anchor points you had on the single line are now on both sides of the fi lled object. Move the anchor points and Bézier handles to thin or thicken the object as it curves and fl ows. Add anchor points as required.

12 To create linear fl owing shapes such as ribbons, you can easily transform a simple line into the perfect shape. Try making the rainbow shown here but much smoother than the drawing. First, create a series of Bézier curves that give the general line – imagine you’re creating the backbone of the intended shape (top). Now make the line much thicker – I went up to 10pt (bottom).

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