How to Animate with Masks in Fireworks CS5
If you’re a Photoshop user, you’re probably familiar with masks. You can take masking a step further in Adobe Fireworks Creative Suite 5 by animating a mask.
Masks let you choose the viewable area of an image. The process is much like cutting a hole in a piece of paper and then placing an image under it. The hole in the paper shows only the area of the image below that you want to expose; the rest of the paper masks (covers) the parts of the image that you don’t want to expose.
Here is how to create a simple object and mask and then animate the mask.
Create an image and a mask
To create the image and mask for your animation, follow these steps:
Create a new document that measures 500 pixels by 500 pixels.
With the Star tool (hidden in the Rectangle tool), create lots of stars close together.
Use any colors and sizes you want for the stars. This step creates multiple layers.
Choose Window→Layers to open the Layers panel.
Click the top layer listed in the Layers panel and then Shift-click the bottom layer to select all the layers you created.
From the panel menu in the Layers panel, choose Flatten Selection.
The layers are flattened into one bitmap layer.
Select the Marquee tool in the Bitmap section of the Tools panel, make a narrow rectangular selection through the middle of the stars, and then click the Add Mask button at the bottom of the Layers panel.
Fireworks creates a mask based on the image area you selected.
Animate the mask
To animate the mask but not the stars, follow these steps:
In the Layers panel, click the chain icon that appears between the stars layer and the mask.
This chain lets you move the layer and mask independently.
In the Layers panel, click the mask to select it.
From the panel menu in the States panel, choose Duplicate State.
The Duplicate State dialog box appears.
Select the After Current State radio button and click OK.
State 2 appears.
With the Pointer tool, select the mask and then drag the mask down slightly on the canvas.
The stars stay in place; only the mask moves.
Repeat Steps 3–5 at least once.
Test your animation by clicking the Play button in the lower right section of the Fireworks workspace.
You can come up with some creative animations by using this technique, perhaps using a logo or other text as a mask.