Automatic squash/stretch animated subclasses of UIView and CALayer.
SMSquashView and its backing class, SMSquashLayer, squash and stretch themselves automatically in response to motion. They will distort themselves longer in the direction of motion, and shorter in the perpendicular directions. The distortion is proportional to the velocity the object, and scaled such that the volume remains constant. In short: it does exactly what you’d want it to do, with no configuration required.
The math is pretty simple, if you like transformation matrices. Every time the layer’s position changes, we note the time and position delta from last time. Using that information we can calculate the velocity for the current frame of animation. We align a transformation matrix to the direction of travel using the same idea as gluLookAt, then scale according to the magnitude of the velocity.
Seriously, just drop it in. It supports all the customization you could want:
squashFactorrepresents the speed above which an object must move to be distortedmaxStretchputs a ceiling on the amount of stretching an object can dominSquashputs a floor on itsmoothMotionwill run a moving average filter to smooth out motion jaggies
…but these are all set to very reasonable values. You may not need to change them.
The original blog post for this project can be found here.
Copyright (C) 2013 by Spaceman Labs
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