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Your monitor paints a new picture 60 times
a second or more.
Imagine your
raspberry jiggles your eyes at exactly the same rate. Then
the screen will seem to move up and down exactly the same way
each time a new picture gets painted.
- The stretch will happen at just the same spot.
- The squish will happen at just the same spot.
In other words, the wave should seem to
stand still.
Now imagine
your eyes jiggle a little slower the monitor scans. The monitor
is gaining on you!
- Each time the scan line comes around, it gets a little closer
to the bottom of the screen before the screen image moves.
If the stretch happened near the top before, it will happen
a little further down next time. And further, and further...
That makes the wave pattern seem to move
downwards.
Now imagine
your eyes jiggle a little faster than the monitor scans. This
time you're gaining on the monitor!
- Each time the screen image moves, the moving scan line hasn't
quite made it as far as it did the last time.
So, the stretch and the squish happen a little closer to the
top each time.
That makes the wave pattern seem to move
upwards.
With a little
practice, you can make the moving wave pattern slow down,
stop, and move off the other way. But watch out you don't get
dizzy blowing all these raspberries! |
