Spirals

Define your own spiral as a function that takes the current radius and returns the current angle in radians

Your function is run for several evenly-distributed radii between 0 and 1. The number of sampled radii increases with time, which leads to interesting animations.

Inspired in part by "The Hypnotic World of Degenerate Spirals"

Functions are defined using a "Reverse Polish Notation" syntax. Here are the different operations it supports:

r the current radius between 0 and 1
n negate the previous value
m absolute value of the previous value
+ add the previous two values
* multiply the previous two values
- subtract the previous value from the one before it
/ divide the previous value from the one before it
& bitwise-and the previous two values
| bitwise-or the previous two values
^ bitwise-xor the previous two values
d duplicate the previous value
s take the sine of the previous value
c take the cosine of the previous value
e Raise the second-to-last value to the last value
P Pi

I use a similar expression format in other places:

TA
Bytebeat