This is the archetypal fractal used when generating perlin noise. It works
simply by adding successive values together to create a final value. As the
succesive values are often calculated at increasing frequencies and the
strength is often decreasing, it will create the impression of ever-smaller
details as you zoom in. This function is intended to be used in conjunction
with `fracture()`

`fbm(base, new, strength, ...)`

## Arguments

- base
The prior values to modify

- new
The new values to modify `base`

with

- strength
A value to modify `new`

with before applying it to `base`

- ...
ignored

## Examples

```
grid <- long_grid(seq(1, 10, length.out = 1000), seq(1, 10, length.out = 1000))
grid$simplex <- fracture(gen_simplex, fbm, octaves = 8, x = grid$x, y = grid$y)
plot(grid, simplex)
```