Billow (cloud-like, lumpy) fractal

The billow fractal is a slight modification of the fbm() fractal. Before adding the new layer onto the last, the new layer is modified by taking the absolute value, multiplying by 2, and subtracting one. The result is that the new value will not contain negative values and so will always add on top of the old values. This function is intended to be used in conjunction with fracture()

billow(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

See also

Other Fractal functions: clamped(), fbm(), ridged()

Examples

grid <- long_grid(seq(1, 10, length.out = 1000), seq(1, 10, length.out = 1000))

grid$simplex <- fracture(gen_simplex, billow, octaves = 8, x = grid$x,
                         y = grid$y)
plot(grid, simplex)