Practical Rendered String Switching in Quartz Composer
I’ve been playing with Quartz Composer and have been able to figure out how to do time based transitions, that can be rendered by a timeline. It’s actually much easier that it seems. And I’m sure there are probably easier ways to get it done.
I was playing with doing title or string transitions, so that I could create a title sequence for lets say a movie or tv commercial. The way I was able to make it move at a precise time, is that I created a composition that had an array of strings, that go into a multiplexer. The source index of the multplexer is being controller by a javascript object that is receiving time from an interpolation object.
The javascript object watches the value that is being generated by the interpolation object, which goes from 0 to 31 – or whatever value you need it to be – with the repeat mode set to none, and the interpolation at linear. If you wanted to get fancy, you could change those to other values, like mirrored loop, or quadratic in and out. You also get the options of sinusoidal, exponential and cubic for interpolation. To make things easier I just picked linear.
Getting back to the javascript object – it essentially does a value comparison (greater than less than) between the signal and point at which I want to switch to a different string. If the value sits between this set of numbers, use this string. If it’s at another one, go to the next one.
And that’s it. With that simple set up, I can transition between a number of different titles a very specific points in time. What makes this useful to me, is the fact that this can be rendered as a quicktime movie. Before doing this I wasn’t ever really sure what was going to be rendered – movements were all very random. Now I have the ability to control the resulting animation with a higher level granularity and specificity.
What makes this even more exciting to me, is knowing that I can use this same composition and apply it to things like lipsync – which was one of the reasons I was thinking of getting a copy of ToonBoom Studio. If I can do it within Quartz Composer, then I won’t have to splash out for that package – and I’ll be in an environment that I’m much more comfortable in.
Links: Dr. Horrible's sing-along blog. Script magazine. Variety. The classic Hollywood rag. Sight and Sound. Classic UK movie magazine. The Internet Movie Script Database.
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