Deeper Modes of Expression, Part 7: Making Decisions

As your expressions become more complex, you will want to start making decisions in the middle of them – for example, if the current value is less than a certain number, do one thing; if it is greater than that number, do something different. Other decisions include “wait until the current time is past the next marker – then do this animation” or even “don’t freak out and give me an error message if you can’t find the marker, keyframe, or other layer you’re looking for.”

These sorts of decisions are often referred to as conditional statements, and expressions in After Effects supports them. The most common type of conditional is know it as an if/then or if/then/else statement. If you are not familiar with JavaScript, their format may be a bit different from what you expect, but they are easy to learn.

A variation on this theme is a do/while loop, which is an essential tool for overcoming expressions’ inability to remember what happened beforehand: You can use these loops to walk through every frame of the animation – accumulating information – until you get to the current frame.

From the Archives: Effective Sound Effects

A few years ago, I wrote an article for Virtual Instruments Magazine on how to use sound effects to help spice up sound tracks and underscores. These same techniques can be used to cover otherwise-awkward edits in soundtracks, and to help tie an otherwise generic piece of stock music more closely to the theme of your video. It has now been re-posted to the ProAudio Coalition channel; click here to view it.

Deeper Modes of Expression, Part 6: Managing Time, Layer Numbers, Speed, and Velocity

By default, expressions assume you are interested in values at the current time. If you need to know the current time, just use the keyword time in an expression, and After Effects will return the current time in seconds (not frames, as we discussed in the previous section).

However, expressions allow you to access values at different points in time. They also let you find out what time keyframes and markers are located at so you can have animations change as they approach or cross one of these keys, as well as reference what other layers are doing. In this installment, we’ll explore a couple of ways to exploit time.

Deeper Modes of Expression, Part 5: Comp, Footage, and Layer Attributes

If you can keyframe it, chances are you can control it with an expression, or use it as part of another property’s expression – usually by dragging the pick whip to it. However, there are additional properties you have access to – including those you can’t access with a pick whip, such as whether a layer’s audio or video switches are on, or its current in or out point. You’ll need to either manually type in code to access these, or get some help from the expression language menu. To give you a taste for what’s possible, let’s discuss a couple of comp and footage attributes of interest.

After Effects CS5

Adobe has officially launched Creative Suite 5, which includes major updates to virtually all of their applications. Adobe has seeded us with preliminary versions, and hired us to help create some documentation on the new release; we wanted to share with you our own impressions plus insights into the new features in After Effects CS5.
In addition to this preview, we also have a 2.5 hour course we’ve created for lynda.com on AE CS5 called After Effects CS5 New Creative Techniques. (If you don’t have a subscription, click here for a free 7-day all-access pass.) Later in June, we are also planning to offer a pair of webinars on the new features in AE CS5 through ProVideoCoalition.com (PVC). Finally, we are also working on the fifth edition of our book Creating Motion Graphics with After Effects (“CMG5” for short), which will cover the major new features in both CS4 and CS5; it should be available around the end of June. But until then, here’s some of the significant new features in After Effects CS5:

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Deeper Modes of Expression, Part 4: Space Conversions

We’re in the process of serializing the Deeper Modes of Expression bonus chapter from our book Creating Motion Graphics with After Effects into a set of 12 posts here on PVC. As you work with Position values and expressions, you will run into the problem of what the Position value really means: Is it a position relative to the layer (such as an effect point), is it a position relative to a parent layer, or is it a position relative to the overall comp (sometimes referred to as “world space”)?

Fortunately, After Effects has a number of layer space transform methods designed to help you move between these different definitions of Position. These are described in the online Help (press F1 to open). Most are straightforward, but there are a few useful transformations that need some extra thought.

Deeper Modes of Expression, Part 3: Deeper Into Arrays

We’re in the process of serializing the Deeper Modes of Expression bonus chapter from our book Creating Motion Graphics with After Effects into a set of 12 posts here on PVC. One of the more mystifying areas of expressions - especially for nonprogrammers - is dealing with arrays. Problems with arrays are the cause of a large bulk of the error messages you will encounter with expressions. Here we will recap the basics, dive into performing additional math operations on arrays, and end with a couple of nice expressions that can measure the distance between layers, or cause one layer to automatically face another.

On lynda.com: Extended Vignette Techniques

Our most recent video course is After Effects: Extended Vignette Techniques, available exclusively through lynda.com. Creating vignettes - darkening or otherwise treating areas of an image in order to focus the viewer’s attention on your desired point of interest - may not seem sexy on the surface, but it is one of the most universal techniques you can learn. This is another one of our “foundational” courses in that rather than going through one whiz-bang project, we demonstrate a basic technique that you can use over and over again in a variety of situations. Vignettes can be used to better frame your subject, fix a poorly-composed shot, give a vintage feel, create “quiet areas” to overlay text and other graphics, blend an image over a new background, or otherwise creatively treat footage.

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