Swink

This video is part of the official comprehensive video course about Duik Ángela

Swink stands for swing or blink¹. It can be used to make a property oscillate between two values, with many options to control the interpolation* between these values. For example, it makes it easy to animate a pendulum or a light blinking.

The first pendulum clock, drawing from Horologium,
Christiaan Huygens, 1658
Public domain.

1. Select the properties
2. Click the Swink button
   
3. Choose one of the presets

The choice between Swing or Blink just change the default values, the same effect is created in both cases.

Effect

The Swink can be adjusted in the effects of the first selected layer.

Duik automatically sets the two values A and B to oscillate around the current value of the selected property. You can adjust these values as you wish, or even animate them.

While the frequency changes the speed of the oscillation, the Cycle offset moves the whole oscillation in time to let you adjust exactly the value from which it starts at the beginning of the composition. This offset is set as a percentage of a complete cycle.

You can use the A/B ratio to let the oscillation spend more time on one or the other value. A ratio higher than 50 % makes the time spent on the A value longer than on the B value, and vice versa.

When the Plateau is set to 0 %, the oscillation never stops; with a higher value, the oscillation will stop some time on both values.

Finally, you can adjust the interpolation* between the A and B values:

• Hold (square) disables interpolation. The value will blink.
• Linear will result in a very simple interpoation without easing (a triangle).
• Smooth (sigmoid) is the smoothest interpolation, similar to a sine function but with the ability to change the easing with the Rate value.
  This interpolation is symetrical, like a sine function.
• Natural (gaussian) interpolates the value using the gaussian (bell) function, which results in an asymetrical acceleration and deceleration. With this interpolation, the motion is more dynamic, and the object looks alive; it is great for the arms swinging during a walk cycle for example.
• Slow down (logarithmic) makes the motion start as fast as possible and quickly slow down when getting to the other value.
• Speed up (exponential) does the opposite of Slow down, making the motion start very slowly and speeding up as much as possible.

With the Smooth, Natural, Slow down and Speed up interpolations, you can use the Rate value to adjust the easing (acceleration and deceleration rate) of the motion.