A layer is a curve wireframe and some parameters that tell Cycle how to process it.

Remember a wireframe is the network of vertices that defines a curve (which could be a filter or waveshape, for example) and the paths between vertices are like rungs along which the curve nodes can travel, morphing the curve.

For instance, a waveshape layer has a pan parameter which lets Cycle know where in the stereo image to put the signal from that layer.

Where are they?

Three places: the Time Surface and the two domains of the Spectrum Filter (harmonic magnitude and harmonic phase).

Each of these has an independent set of layers.

Layer Parameters

All layers have a pan parameter.

Harmonic Magnitude layers have a parameter called range. It controls amount of influence the curve has on the spectrum.

If the curve is in filtering mode, this is roughly equivalent to the steepness of a filter. If the curve forms a resonance peak, the range knob effectively controls the resonance strength.

In the harmonic phase domain, the equivalent parameter is called width, measured in radians.

In some future version of Cycle, fine-tune values for waveshape-layers will be introduced, effectively giving the synth unlimited true oscillators.

Spectral Layer Modes

Harmonic magnitude layers have two modes: additive and subtractive mode.

In additive mode, the curve adds harmonics, even if there were none to begin with.

Some presets do not start with a waveshape at all, and the sound is generated purely from adding harmonics to a blank spectrum.

Subtractive layers multiply with the harmonic spectrum of the layers beneath it, so such a layer at the bottom of the layer stack wouldn't do squat if there wasn't a spectrum for it to filter. So generally, you put the subtractive layers above the others.

Don't cross paths

So what's the point of layers? Well, you may have noticed that vertex paths aren't supposed to cross eachother. There's a good reason for this, and it's about not distorting the sound unintentionally.

If in the menu bar Edit->Collision Detection is turned off, and you move vertices around, it's hard to avoid their paths crossing eachother and causing "glitches" in the sound.

You can definitely make some cool noises that way, but in general use, it's not what you'd want.

However, sometimes you need patterns to cross, say if there are multiple resonance peaks (like in the Buddha preset). Also sometimes in the time domain you might want to simulate detuning and paths will overlap, so to do this in Cycle we need multiple layers.

Vertex paths on different layers don't interact with eachother, so there's no glitching problem.

Stereo Image

Another use for layers is to pan them to opposite sides and make a truly stereo tone.

You can pan layers in all domains. To make stereo noise, pan two waveshape layers each with a noise deformer to either side. In the harmonic phase domain, a similar pair of noise layers will make a nice stereo breathiness.

Scratch Channel Mapping

Another feature is that each layer can be routed to its own scratch envelope, or they can share one, depending.

In effect, different layers can loop at different speeds and transform independently.