Building on the previous post about iterators in Quartz Composer, here’s an example that shows how to draw a spiral.
Here’s what it looks like:
The spiral is composed of segments that progress outward radially from the origin. Each successive endpoint is computed as a polar coordinate (Degrees, Distance), then converted to a cartesian (X,Y) coordinate relative to the origin.
This also shows the basics of using LFOs (low frequency oscillators) to automate parameters that change over time: a Sawtooth LFO is used to rotate the spiral, and a Sine LFO is used to grow and shrink it.
You can download the source file here:
