mollusc: Generate mollusc data
In marcusvolz/mathart: Create mathematical art with R

Generates data for plotting mollusc shells and stores it in a data frame with (x, y, z) coordinates. The shell model is described in the paper "Models for mollusc shell shape" by M.B. Cortie (1989).

mollusc(
  n_s = 1000,
  n_t = 4000,
  alpha = 80,
  beta = 40,
  phi = 55,
  mu = 30,
  Omega = 10,
  s_min = -270,
  s_max = 62,
  A = 25,
  a = 12,
  b = 16,
  P = 2,
  W_1 = 1,
  W_2 = 1,
  N = 0,
  L = 0,
  D = 1,
  theta_start = 0,
  theta_end = 10 * pi
)

`n_s`	Number of points to generate with respect to s
`n_t`	Number of points to generate with respect to theta
`alpha`	Equiangular angle of spiral (degrees)
`beta`	Angle between z-axis and line from aperture local origin to xyz origin (degrees)
`phi`	Tilt of ellipse major axis from horizontal plane (degrees)
`mu`	Amount of "leaning over" of aperture (degrees)
`Omega`	Amount of azimuthal rotation of aperture (degrees)
`s_min`	Angle at which aperture-generating curve begins (degrees)
`s_max`	Angle at which aperture-generating curve ends (degrees)
`A`	Distance from main origin to local origin of aperture at theta=0
`a`	Major radius of ellipse at theta=0
`b`	Minor radius of ellipse at theta=0
`P`	Position of nodule in terms of the angle, s (degrees)
`W_1`	Width of nodule in s-direction (degrees)
`W_2`	Width of nodule in theta-direction (degrees)
`N`	Number of nodules per whorl
`L`	Height of nodule at theta=0
`D`	Sense of coiling; 1=dextral, -1=sinistral
`theta_start`	Required for shells such as Dentalium or Diodora, which grow at one end while dissolving at the other. In all other cases set to -Inf
`theta_end`	Not important for self-similar shells, except very small or large values can cause computational problems