Hair Material

hair(
  pigment = 1.3,
  red_pigment = 0,
  color = NA,
  sigma_a = NA,
  eta = 1.55,
  beta_m = 0.3,
  beta_n = 0.3,
  alpha = 2
)

Arguments

pigment: Default `1.3`. Concentration of the eumelanin pigment in the hair. Blonde hair has concentrations around 0.3, brown around 1.3, and black around 8.
red_pigment: Default `0`.Concentration of the pheomelanin pigment in the hair. Pheomelanin makes red hair red.
color: Default `NA`. Approximate color. Overrides `pigment`/`redness` arguments.
sigma_a: Default `NA`. Attenuation. Overrides `color` and `pigment`/`redness` arguments.
eta: Default `1.55`. Index of refraction of the hair medium.
beta_m: Default `0.3`. Longitudinal roughness of the hair. Should be between 0 and 1. This roughness controls the size and shape of the hair highlight.
beta_n: Default `0.3`. Azimuthal roughness of the hair. Should be between 0 and 1.
alpha: Default `2`. Angle of scales on the hair surface, in degrees.

Value

Single row of a tibble describing the hair material.

Examples

#Create a hairball
if(run_documentation()) {
#Generate rendom points on a sphere
lengthval = 0.5
theta = acos(2*runif(10000)-1.0);
phi = 2*pi*(runif(10000))
bezier_list = list()

#Grow the hairs
for(i in 1:length(phi)) {
  pointval = c(sin(theta[i]) * sin(phi[i]),
               cos(theta[i]),
               sin(theta[i]) * cos(phi[i]))
  bezier_list[[i]] = bezier_curve(width=0.01, width_end=0.008,
                                  p1 = pointval,
                                  p2 = (1+(lengthval*0.33))*pointval, 
                                  p3 = (1+(lengthval*0.66))*pointval,
                                  p4 = (1+(lengthval)) * pointval,
                                  material=hair(pigment = 0.3, red_pigment = 1.3,
                                                beta_m = 0.3, beta_n= 0.3),
                                  type="flat")
}
hairball = dplyr::bind_rows(bezier_list)

generate_ground(depth=-2,material=diffuse(color="grey20")) %>%
  add_object(sphere()) %>%
  add_object(hairball) %>%
  add_object(sphere(y=20,z=20,radius=5,material=light(color="white",intensity = 100))) %>%
  render_scene(samples=16, lookfrom=c(0,3,10),clamp_value = 10,
               fov=20, width=800, height=800)
}

if(run_documentation()) {         
               
#Specify the color directly and increase hair roughness
for(i in 1:length(phi)) {
  pointval = c(sin(theta[i]) * sin(phi[i]),
               cos(theta[i]),
               sin(theta[i]) * cos(phi[i]))
  bezier_list[[i]] = bezier_curve(width=0.01, width_end=0.008,
                                  p1 = pointval,
                                  p2 = (1+(lengthval*0.33))*pointval, 
                                  p3 = (1+(lengthval*0.66))*pointval,
                                  p4 = (1+(lengthval)) * pointval,
                                  material=hair(color="purple",
                                                beta_m = 0.5, beta_n= 0.5),
                                  type="flat")
}
hairball = dplyr::bind_rows(bezier_list)
generate_ground(depth=-2,material=diffuse(color="grey20")) %>%
  add_object(sphere()) %>%
  add_object(hairball) %>%
  add_object(sphere(y=20,z=20,radius=5,material=light(color="white",intensity = 100))) %>%
  render_scene(samples=16, lookfrom=c(0,3,10),clamp_value = 10,
               fov=20, width=800, height=800)
}