Adobe After Effects CS5 : Building a 3D object (part 2)

Positioning 3D elements

When you build a 3D object, you need to position the 3D layers in relationship to each other. You’ll position the spine of the book by moving its anchor point and then adjusting the front cover as necessary.

1.	Drag the AESpine.jpg item from the Project panel into the Timeline panel, placing it at the top of the layer stack.
2.	Select the 3D Layer switch () for the AESpine.jpg layer.
3.	Ctrl-click (Windows) or Command-click (Mac OS) the triangle in the Label column for the AESpine.jpg layer to display all of its Transform properties.
4.	Click the y-axis value (the middle value) for the Anchor Point property, and then add *2, so that its value is 617*2. Press Enter or Return to accept the calculation.

As with the front cover, moving the anchor point for the spine positions it to sit on the floor of the 3D space. However, the spine is facing the same direction as the front cover. You’ll need to rotate it.

Now the spine is facing the right direction, but it’s in the middle of the front cover. To move it into place, you’ll use the same simple math trick you used to position the book on the floor.

The AESpine.jpg layer currently intersects the middle of the AEFront.jpg layer. Therefore, moving the spine 500 pixels to the left will align it appropriately. To move an object to the left on the x axis, subtract pixels.

The spine moves to the end of the book. It’s close, but it protrudes from the front of the book. You’ll move the AEFront.jpg layer forward to fix that.

8.	In the Timeline panel, select the AEFront.jpg layer, and then press P to display its Position property.
9.	Click the z-axis value (the third value) for the Position property of the AEFront.jpg layer, and change the value to -56. A negative value on the z axis moves the layer toward the active camera view (forward).
10.	Close all properties for the AESpine.jpg and AEFront.jpg layers to keep the Timeline panel neat.

Replacing a 3D element with another

Instead of repeating all the steps to position the back cover, you’ll duplicate the front cover and replace it with the back cover.

1.	Select the AEFront.jpg layer in the Timeline panel, and press Ctrl+D (Windows) or Command+D (Mac OS) to duplicate the layer.
2.	With the duplicate layer selected, press P to display its Position property.
3.	Change the z-axis value to +56 to move the layer away from the active camera view. Because this will be the back cover, you want to position it at the back of the spine, which is 112 pixels wide.
4.	In the Composition panel, change the right view to Custom View 3 so you can see both ends of the book.
5.	With the duplicate layer selected in the Timeline panel, press R to display the layer’s Rotation properties, and change its Y Rotation value to 180 degrees. The rotation flips the layer.
6.	With the duplicate layer selected in the Timeline panel, press Alt (Windows) or Option (Mac OS) as you drag the AEBack.jpg item from the Project panel onto the duplicate layer. After Effects replaces the front cover with the back cover, and changes the layer name to AEBack.jpg.

Adjusting views with the camera tools

By definition, 3D objects can appear different from different angles. You can adjust the camera view to see the object from other directions so that you can identify gaps, make positioning adjustments, and otherwise evaluate and plan your project.

1.	Select the Track Z Camera tool (), hidden behind the Unified Camera tool () in the Tools panel. The Track Z Camera tool lets you zoom in and out of a composition view.
2.	Click in the left view (Custom View 1) in the Composition panel to ensure it’s active. Then click and drag to the left or down to zoom out from the scene and see the entire book. You may need to click and drag multiple times.
3.	Select the Orbit Camera tool (), hidden behind the Track Z Camera tool in the Tools panel. The Orbit Camera tool rotates the current 3D view by moving the camera around the point of interest.
4.	Drag the Orbit Camera tool to the left or right in the left view of the Composition window so that you can see the back of the book. Remember, when you’re using the Orbit Camera tool, you’re rotating the view, not the object itself.
5.	Drag the Orbit Camera tool again so that you are viewing the front of the book.
6.	Select the Selection tool () in the Tools panel, and choose File > Save to save your work so far.

Adding solid layers to a 3D object

You’ve assembled the front cover, back cover, and spine of the book. But it’s still lacking a top and right side (opposite the spine). Because these sides don’t require specific content, you can create them using solid layers.

1.	Click in the Timeline panel. Then press Ctrl+Y (Windows) or Command+Y (Mac OS) to create a new solid layer.
2.	In the Solid Settings dialog box, name the layer Top Pages, change the width to 1000 pixels (to match the cover width), and the height to 112 pixels (to match the width of the spine).
3.	Click the eyedropper, and click a white area of the book cover to sample it. Click OK to create the layer.
4.	Select the 3D Layer switch () for the Top Pages layer.
5.	Press R to display the Rotation properties, and change the X Rotation property to 90 degrees.
6.	Press P to display the Position property. Click the y-axis value, and type 240-1234. Press Enter or Return to accept the calculation.

Why those numbers? The current position is 240, and you want to move it up the height of the book, which is 1234 pixels.

7.	Press Ctrl+Y (Windows) or Command+Y (Mac OS) to create another solid layer for the right side of the book, representing the edges of the pages that are bound by the spine on the left side.
8.	In the Solid Settings dialog box, name the layer Pages, change the Width to 112 pixels (the width of the spine) and the Height to 1234 pixels (the height of the covers). Make sure the layer is white, and then click OK.
9.	Select the 3D Layer switch () for the Pages layer.

The Pages layer needs to be on the right side of the book. You’ll change its Anchor Point, Rotation, and Position properties to get it there.

10.	Ctrl-click (Windows) or Command-click (Mac OS) the triangle next to the Label column for the Pages layer to display all its Transform properties. Note For this project, it’s unlikely that anyone will see the bottom of the book. But if you want to add a bottom layer, duplicate the top layer and move it into position.
11.	Change the y-axis value for the Anchor Point property to 1234 (placing the layer on the virtual floor); change the Y Rotation amount to 90° to make it face the right direction; and change the x-axis value for the Position property to 360+500 to move the layer to the right side of the book. Tip Pressing the U key multiple times cycles through the reveal/hide options.
12.	With the Timeline panel active, press Ctrl+A (Windows) or Command+A (Mac OS) to select all the layers. Then press the U key to close all the properties for the layers.