mathart (version 0.0.0.9000)

mollusc: Generate mollusc data

Description

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).

Usage

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
)

Arguments

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

Examples

# NOT RUN {
mollusc()
# }