TECH TIPS

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Star Turn
Creating and Animating Shape Blends with Adobe Illustrator
by Ben Bardens

Figure 1: The Illustrator toolbox, showing the Star tool, Blend tool, Fill and Line swatches and "none" button.

In this two-part tutorial, I’ll demonstrate how to use Adobe Illustrator to create shape blends that can be used as animation sequences in Adobe After Effects. This is a great technique for creating animated objects for use as elements in a larger project. In this example, we’ll create an animated star that could ultimately be used as a particle in a larger effect, like a star field. As you complete the tutorial, keep in mind that for your own projects the shapes don’t necessarily have to be stars––they could be any vector objects. For example, simple logos and icons can work well for this effect.

It is not necessary to download any tutorial files to complete this project, although a sample project for your reference can be downloaded from:
http://www.barkanimation.com/guild/23.zip.

Setting up a new document and creating custom star shapes
Create a new document in Illustrator. Specify artboard size as 800 x 600 pixels with landscape orientation and RGB color. Save the file with the default Illustrator settings and name it “star-sequence.ai.”

Select the Star tool. It’s hidden behind the Rectangle tool (see figure 1).

Click and drag across the artboard to create a star approximately three-to-four inches in diameter. Before releasing the mouse, while clicking and dragging, use the up and down arrow keys on your keyboard to control how many points the star has. Create an eight-pointed star.

Click and drag across another area of the artboard to create a second star. This time make a 16-point star.

If either of the stars extend far beyond the edge of the artboard (the solid black line around the edge of the page), or either star needs to be scaled up or down, use the Selection tool to reposition/resize either star (hold the Shift key while dragging on an object’s corner box to resize it proportionally). Exact placement and size doesn’t matter, as long as you can see both stars and they are close in size.

Using the Selection tool, click on the first star you created to select it. From the Filter menu, choose Distort -> Pucker & Bloat.

If necessary, position the Pucker & Bloat dialogue alongside the star and check the “Preview” box.

Adjust the slider from side to side and view the results. Choose a setting that you think looks cool (I used –87 in the sample file). Click OK.

What’s the difference between a Filter and an Effect? Effects do not permanently change the vector shape of the object and can be edited at any time via the “appearance” palette. Filters do permanently change the vector shape of an object (the actual location of the vertex points and lines) and are not modifiable once applied. If you are creating objects in Illustrator for use in another program, and you want to interpret the objects as scalable vectors rather than rasterizing as bitmaps, use Filters rather than Effects to style your objects.

Using the Selection tool, click on the second star to select it. From the Filter menu, choose Distort -> Zig Zag.

Again, position the dialogue and check the “Preview” box so you can view the results as you experiment with the settings.

Adjust the settings to your liking. In the sample file I specified an Absolute Size of 6 px with 11 Ridges per segment and Smooth Points. When you are happy with the results, click OK.

At this point, you’ve got two unique looking stars within your document. Take a moment, using the Selection tool, to position and size the stars (remember to hold Shift when resizing so the stars stay proportional). Again, the exact locations and sizes don’t matter, as long as you can see both stars and they are close to the same size in diameter.

Before continuing, specify stroke and fill values for the two stars. While you can color the objects here inside of Illustrator, you can also do so inside of After Effects using the simple Tint filter. To take advantage of the Tint filter, it is useful to make your objects solid black in Illustrator. Select both stars by typing Command A (Mac) or Control A (PC) to select all.

In the toolbox, click the Fill color to activate it (see figure 1). Then, from the Swatches palette, click on the black swatch (if the Swatches palette isn’t visible, choose Window -> Swatches).

Back in the toolbox, click the Stroke color to activate it (see figure 1). Then, from directly below, click the “none” button to remove the stroke value.
Save your file.

Using the Blend tool to create an animation sequence

Choose View -> Show Grid.

Using the Selection tool, click on the left star. Hover the selection tool over one of the corner boxes until you see the rotate icon. Using the lines in the grid, click and rotate the star so that its top and bottom points line up vertically (see figure 2).

Figure 2: Rotate the stars so that their top and bottom points line up vertically.

Repeat for the right star.

Choose View -> Hide Grid.

For the next series of steps, you need to have both stars selected. Type Command A (Mac) or Control A (PC) to select all.

In the toolbox, select the Blend tool (see figure 1).

Choose Object -> Blend -> Blend Options or double-click the blend tool in the toolbox.

In the Blend Options dialogue, change Spacing to Specified Steps and 28. Leave the Orientation set for Align to Page and Click OK.

The number of steps determines the number of “in-between” frames for our animation sequence. We have two shapes to start with. By creating 28 more, we will have a final animation sequence of 30 frames.

Hover the cursor over the tip of the lowest point of the left star until you see a little “X” appear next to the cursor. Then single-click. This defines the starting blend point.

Figure 3: The two star shapes with the 28-step shape blend between them.

Hover the cursor over the corresponding lowest tip on the right star until you see a little “+” appear, and then click. A blend showing 28 new “in-between” shapes appears between the two stars (see figure 3).

Choose Object -> Blend -> Expand. This converts the blend object into a series of discretely editable shapes.

Choose Object -> Ungroup.

Figure 4: The horizontal and vertical align buttons on the Align palette.

Choose Window -> Align to display the Align palette. Click on the Horizontal Align Center and the Vertical Align Center buttons (see figure 4).

Go to the Layers palette and click the little triangle to the left of the layer name (Layer 1) to expand the layer (see figure 5).

From the fly-out menu in the top right corner of the Layer palette, choose Release to Layers (Sequence).

Figure 5: Expand the layer in the layer palette by clicking the triangle to the left of the layer name.

Scroll back to the top of the layer stack. Notice that even though the Release to Layers command converted all the individual paths into individual layers, they are still nested within “Layer 1.” Because Illustrator is an object-based program, it is possible to have layers nested within layers. This is great for designing complex graphics within Illustrator. But in order to get After Effects to interpret the layers correctly, they must be un-nested and at the root level within the layers palette.

Select Layer 2 by single-clicking on it in the Layers palette.

Scroll all the way to the bottom of the layer stack and then shift-click on Layer 31. Layers 2 through 31 should now all be selected.

Scroll back to the top of the layer stack (being careful not to deselect the layers).

Click and hold on Layer 2 and carefully drag it above Layer 1. When you see the bolded black line above Layer 1, release the mouse. All the selected layers should now be un-nested and above Layer 1 in the stack. If it doesn’t work and the layers become deselected, repeat the last few steps.

Scroll to the bottom of the layer stack and locate Layer 1. There are now no objects on Layer 1. Delete it by dragging it to the little trashcan icon at the bottom of the palette. Save your file.

As a last step before taking the file to After Effects, select all and use the selection tool to make sure the entire stack of layers is located within, and not being clipped by the artboard (the black line around the edge of the page). Take care not to mess up the alignment of the individual layers. If necessary, you can use the Align palette to make sure that all the layers are centered both horizontally and vertically again, as in step 29 above.

Save and close your file.

That’s all for this issue. Next time, we’ll take this layered Illustrator file into After Effects and learn tricks and techniques for sequencing it, timing it out and adding effects.

Ben Bardens teaches After Effects at Glendale Community College and works as a freelance graphic artist. Learn more about his classes by visiting www.glendale.edu/~bbardens or by e-mailing him at bbardens@glendale.edu.

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