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Layering Animated Objects
Part of the "art" of custom animation is in thinking about which objects should appear and disappear and in what order. Theoretically, you could layer all the objects for every slide in the entire presentation on a single slide and use custom animation to make them appear and disappear on cue.| Caution | If you are thinking about creating complex layers of animation where some objects disappear and are replaced by other objects on the same slide, first take a step back and consider whether it would be easier to simply use two or more separate slides. When there is no delay or animation defined in the transition between two slides (if their content is identical or very similar), the effect is virtually identical to that of layered animated objects-with much less time and effort to set up. |
Layering can be useful when you want part of a slide to change while the rest of it remains static. For example, you could create your own animated series of illustrations by stacking several photos and then animating them so that first the bottom one appears, then the next one on top of it, and so on. This can provide a rough simulation of motion video from stills, much like flipping through illustrations in the corners of a stack of pages. Set the animation speeds and delays between clips as needed to achieve the desired effect.When objects are stacked, the new object placed over the top of the old obscures the old one, so it is not necessary to include an exit action for the item beneath. However, if the item being placed on top is smaller than the one beneath, you will want to set up an exit effect for the one beneath and have it occur concurrently (that is, With Previous) with the entrance of the new one.An example may make this clearer. Suppose, you want to place a photo on the right side of a slide and some explanatory text for it at the left, and then you want it to be replaced by a different photo and different text (see Figure 13-22).
Figure 13-22: First the slide should appear as shown at top, and then it should change to show the content shown at bottom.
To set this up to occur all on the same slide, you would first place the content that should appear first, and then apply exit effects to the content, as shown in Figure 13-23. Notice that the picture is set to On Click for its exit effect, which will make the picture disappear when you click. The accompanying text box is set for With Previous, which means that it will disappear at the same time that the picture disappears.
Figure 13-23: Place the "bottom" layer object first and animate the objects with exit effects.
Next, I'll place the other text box and other picture over the top of the first items. The new photo obscures the old text box.Then, I'll animate the new text box, and the new picture with entrance effects that are set to With Previous, so that both will appear at the same time that the other two items are exiting (see Figure 13-24). Notice that they all have the same animation number, 1, because they all occur simultaneously.
Figure 13-24: Place the next layer of objects on the slide, and animate their entrances to be With Previous.
It's always a good idea to preview animation effects in Slide Show view after creating them. Click the Slide Show View icon in the bottom left corner of the screen to preview the active slide, then press Esc to return to PowerPoint.
