Recipe 54: Zoom

General Principles

  • Creating an endless zoom effect
  • Making a circular mask with Gen


This is a classic use of Jitter to create a sort of endless transition effect. This recipe is also a great example of how sometimes the best effects come from how something is controlled, not just advanced visual processing tricks.




To create a constant, overlapped zoom effect we use two identical being fed the same masked image. The object is just applying a circular, feathered mask to the alpha channel of the image to create a soft vignette.

Most of the action of this effect is centered around the counter object at the top. The on the left is getting scaled directly from the counter output. The expr is there to make the scaling look more like perspective zooming than just linear scaling, which would appear to slow down as it got bigger. As the counter reaches half of its range, the layers are swapped, and the loop of the righthand begins.

The overlap is accomplished by offsetting the counter output by half the range and then performing a modulo on that. This makes it so that each videoplane has the same looping time, but they are half of a loop offset from each other. By combining these simple attribute sequencing techniques, we get a nice perpetual zoom effect. To further develop this idea, you could create multiple videoplanes with loop offsets that are some ratio of the loop length and come up with a system for managing layer rotation. You could also think of other sorts of effects that use pairs or multiples of images that have overlapping attribute sequences.

June 10, 2012 | 12:20 pm

I’m really fascinated by gen/pix but, I don’t understand it clearly.

How can I give an offset to the radial gradient center?

Thank you very much.

June 10, 2012 | 9:42 pm

Hi there – Max user here, kinda curious (but also completely ignorant) about Jitter and Gen. Every time I have a bit of a sniff around (for example, by reading about this Zoom recipe) I’m still completely lost. And d’ya know what I reckon would help a LOT? (AN) EXAMPLE(S) OF THE PATCH BEING USED!!! (Please…)

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