Class 4: Bézier Paths

Note to everybody:

Set Illustrator's Workspace to “Classic Essentials” (not “Essentials”)
Menu > Window > Workspace > Classic Essentials

Change in Assignments start dates, due dates, and length of time

Assignment 1: Personal ID

Start: Class 6 (9/27)
Due: Class 8 (10/11)
Duration: 2 Weeks

Assignment 2: Tattoo

Start: Class 8 (10/11)
Due: Class 11 (11/1)
Duration: 3 Weeks

Assignment 3: Beverage Label

Start: Class 11 (11/1)
Due: Class 14 (11/22)
Duration: 3 Weeks

Assignment 4: Poster

Start: Class 14 (11/22)
Due: Finals Class (12/13)
Duration: 3 Weeks

The Path Tool

From the world of Bézier math, invented in 1962 by Pierre Bézier to design automobile bodies for Renault. Based, in part, on an old technique of drawing curves mechanically with long flexible rulers and anchors to hold the rulers at specific points to the drafting table.

Path Symmetry paths-symmetry.ai.zip

Make a set of straight-line segments

Turn on the Grid and Snap to Grid
Menu >
View >
Show Grid, Menu >
View >
Snap to Grid

Choose the Path tool from the Tools Panel
Tool Panel >
Click/Release Path Tool

Click (but don't drag) a point.
Click/Release
Move the cursor over 1" and up 1" on the grid and click again (but don't drag)
Move >
Click/Release

Repeat to make a zigzag line
Move >
Click/Release >
Move >
Click/Release

Oops! It's a filled object.

Set the fill to none in the Control Panel
Switch to Selection Tool >
Click/Release path >

Click/Release Fill tab >
Click/Release No Fill Swatch

Start again and make a zig zag line
Click/Release >
Move >
Click/Release >
Move >
Click/Release

Make a set of curved path segments

This time, let's click with the Pen Tool and drag
Shift-drag straight up 1 inch...
Click/Hold >
Drag

Then click 1 inch to the left and shift-drag 1 inch down...
Move >
Click/Hold >
Drag

Repeat, alternating up and down directions
Move >
Click/Hold >
Drag >
Move >
Click/Hold >
Drag, etc.

Now a set with shorter direction handles

Shift-drag up 1/2 inch...
Click/Hold >
Drag

Move >
Click/Hold >
Drag

Move >
Click/Hold >
Drag >
Move >
Click/Hold >
Drag, etc

Now a set with diagonal direction handles

Shift drag from the starting anchor point up and right 1 inch
Click/Hold >
Drag

A very different curve!
Click/Hold >
Drag >
Move >
Click/Hold >
Drag

Move >
Click/Hold >
Drag >
Move >
Click/Hold >
Drag, etc.

Now a set of shorter diagonal direction handles

Only 1/2 inch up and right this time
Click/Hold >
Drag

Move >
Click/Hold >
Drag

The example file (paths-symmetry.ai.zip) has a few more variations – try them out!

Making An Ellipse With The Path Tool

It's an interesting exercise to make an ellipse with the path tool. It may help in getting a "feel" for how anchor points and direction handles work.

Start fresh

Make a new artboard or a new file, make sure Grid is on
Menu >
New >
New Document Dialog >
Size:Letter >
Click:OK
Menu >
View >
Show Grid

Draw a 2 inch circle with the ellipse tool, then another ellipse that 2 inches tall and 3 inches wide

Tool Panel >
Click/Hold Rectangle Toll until popup menu >
Drag to Ellipse Tool>
Release
Shift/Hold >
Click/Drag 2in left + 2in down >
Release
Shift/Hold >
Click/Drag 3in left + 2in down >
Release

Select both ellipses
Tool Panel >
Click/Release Selection Tool >
Shift/Hold >
Click/Release first circle/ Release Shift

Add some guides:
Menu >
View >
Guides >
Make Guides

Select them both and use Menu >
View >
Guides >
Make Guides to turn the ellipses into guides

Use the Path Tool to re-create the four anchor points and distance handles of Illustrator's Ellipse Basic Shape Tool

Start on the left side, drag up about 1/2 inch

Click on the top side, drag right about the same

Zoom in. Turn Snap to Grid off. Use the Direct Selection tool to tweak the handles until the curve matches the circle as closely as possible.

Choose Menu >
View >
Show Rulers.

Click on the top ruler and drag the cursor down. A horizontal line appears with the cursor. Drag down until you intersect the line with the end of the left-side anchor point's handle's top. Release.

Re-select the path so the handles show. Do the same from the left ruler and drag the cursor to the right. A vertical line appears, etc.

Use these new horizontal and vertical guides (and two additional guides) to align the other handles as you complete the circle.

NOTE: To continue a path, choose the path tool and bring the cursor to the end-anchor of the path you want to continue. You'll see this icon:

Use the same techniques to create the 2x3 ellipse

How Long To Make The Handle & How Many Anchor Points?

The "distance handle" controls the shape of the curve along with the anchor point. Let's examine how the length and angle of the handles affect the curve, and how the number of anchor points also affects it.

A basic rule of thumb:

The fewer anchor points, the smoother the curve

Make a new document or add a new artboard to the current doc

With Snap to Grid on, create a simple curve with 45º handles, 6 inches wide

Menu ><br> Object ><br> Transform ><br> Move...

Select it, then use Menu >
Object >
Transform >
Move...

And use the dialog to make a copy of it 1 inch down

The result

Repeat the move with Transform Again, or better yet, Control/Command-D, 3 times

Now select the 4 lower curves and convert them to Guides with
Menu >
View >
Guides >
Make Guides

Zoom into the top guide. Let's define a curve with three anchor points that fits the guide

Compare the original curve's two anchor points and handles to the new three anchor pointed curve's. Note that the two point curve has longer handles

Try with the next two curves with handles that are too long and too short

Try the last curve with a bunch of anchor points. Notice how much tweaking is required to make the curve look smooth.

Here (Again) Is The Example File (paths-symmetry.ai.zip) With All The Curves In It So Far.

Types of Anchor Points

End Anchor	Every line has at least two anchors
Corner Anchor Point	Has no handles Created with click-release
Smooth Anchor Point	Has two handles, equidistant from the anchor, in alignment with each other Created with click-drag-release
Combination Smooth Anchor Point	Smooth on both sides, with two handles, but handles are not aligned Created with click-drag-option/alt-drag-release
Combination Anchor Point	Curved on one side, smooth on the other, with one handle for the smooth side Created by click-drag-release then click again on anchor

Some Important Pen Tool Keyboard/Mouse Gestures To Remember:

Gesture	Result
Click-release	Corner point
Click-drag-release	Smooth point
Click-spacebar or click-drag-spacebar followed by release	Moves point while spacebar is down, then fixes point on release
Click-drag then hold Alt/Option	De-couple handle from other handle
Click-drag-release then click-release on anchor point	Change leading handle to straight-line corner anchor
Click-drag-release then click-drag-release on anchor point	Change leading handle to straight-line corner anchor

Truth is, I almost never can remember all of these. Instead, I just rough out the curves I want and go back in and edit them until I get the effect I want.

Tracing With The Path Tool

The source paths-tracing.ai example file, and the source acanthusleaf.jpg file

Make a new doc

Choose Menu >
File >
Place

Place the acanthusleaf.jpg file in the middle of the artboard

Use the opacity slider in the Control Panel to set the opacity to 50%

Use the Layers Panel to lock the acanthus leaf image

Start tracing the leaf with as few anchor points as possible. Just rough it out, we'll refine it later. The key is to look for the outer edges of curves and drag out a handle that's tangent to the curve

Remember tangents from Geometry? Here's a refresher:

A tangent line is a line which sits perpendicular (at a right angle) to the point on a curve

And so on... the only way to really demo this is to show it live. Here's the resulting file.