Make the Sperm Swim Aimlessly

Noise is a very flexible tool to get some random variations in movement, colors and shape. Here we use noise to give squiggle shapes a random, non-repeating, but smooth path.

We use the noise1 CHOP to generate three channels, each different, containing a smooth random curve. The three channels will be the X, Y and Z of the path of the squiggle. The red curve is the original 10 seconds of noise. The white curve is noise made cyclic using a Cycle CHOP, so it repeats smoothly after 10 seconds.

We then trim the CHOP so that it gives us the most recent second (30 frames) of the noise for all 3 channels. Then we use the resample1 CHOP on the 30 frames to make it 8 samples long. We will use the 8 samples as the backbone of the squiggle.

The three channels with the 8 samples are sent to the SOP Editor, the procedural modeler. Here the 3 channels are brought in to be the XYZ points of an 8-point line. The sweep1 SOP takes that line as a backbone, and a set of 8 circles, and sweeps the 8 circles along the backbone, then skins them together into one surface.

Because the most recent 1-second of the trimmed CHOP changes every frame. the squiggle is changing shape every frame and appears to be following a path.