Arrow Object

Composite object (cone + segment)

arrow(
  start = c(0, 0, 0),
  end = c(0, 1, 0),
  radius_top = 0.2,
  radius_tail = 0.1,
  tail_proportion = 0.5,
  direction = NA,
  from_center = TRUE,
  material = diffuse(),
  flipped = FALSE,
  scale = c(1, 1, 1)
)

Arguments

start

Default `c(0, 0, 0)`. Base of the arrow, specifying `x`, `y`, `z`.

end

Default `c(0, 1, 0)`. Tip of the arrow, specifying `x`, `y`, `z`.

radius_top

Default `0.5`. Radius of the top of the arrow.

radius_tail

Default `0.2`. Radius of the tail of the arrow.

tail_proportion

Default `0.5`. Proportion of the arrow that is the tail.

direction

Default `NA`. Alternative to `start` and `end`, specify the direction (via a length-3 vector) of the arrow. Arrow will be centered at `start`, and the length will be determined by the magnitude of the direction vector.

from_center

Default `TRUE`. If orientation specified via `direction`, setting this argument to `FALSE` will make `start` specify the bottom of the cone, instead of the middle.

material

Default diffuse.The material, called from one of the material functions diffuse, metal, or dielectric.

flipped

Default `FALSE`. Whether to flip the normals.

scale

Default `c(1, 1, 1)`. Scale transformation in the x, y, and z directions. If this is a single value, number, the object will be scaled uniformly. Notes: this will change the stated start/end position of the cone. Emissive objects may not currently function correctly when scaled.

Value

Single row of a tibble describing the cone in the scene.

Examples

#Draw a simple arrow from x = -1 to x = 1
if(run_documentation()) {
generate_studio() %>% 
  add_object(arrow(start = c(-1,0,0), end = c(1,0,0), material=glossy(color="red"))) %>% 
  add_object(sphere(y=5,material=light(intensity=20))) %>% 
  render_scene(clamp_value=10,  samples=128)
}

if(run_documentation()) {
#Change the proportion of tail to top
generate_studio(depth=-2) %>% 
  add_object(arrow(start = c(-1,-1,0), end = c(1,-1,0), tail_proportion = 0.5,
                   material=glossy(color="red"))) %>% 
  add_object(arrow(start = c(-1,0,0), end = c(1,0,0), tail_proportion = 0.75,
                   material=glossy(color="red"))) %>% 
  add_object(arrow(start = c(-1,1,0), end = c(1,1,0), tail_proportion = 0.9,
                   material=glossy(color="red"))) %>% 
  add_object(sphere(y=5,z=5,x=2,material=light(intensity=30))) %>% 
  render_scene(clamp_value=10, fov=25,  samples=128)
}

if(run_documentation()) {
#Change the radius of the tail/top segments
generate_studio(depth=-1.5) %>% 
  add_object(arrow(start = c(-1,-1,0), end = c(1,-1,0), tail_proportion = 0.75,
                   radius_top = 0.1, radius_tail=0.03,
                   material=glossy(color="red"))) %>% 
  add_object(arrow(start = c(-1,0,0), end = c(1,0,0), tail_proportion = 0.75,
                   radius_top = 0.2, radius_tail=0.1,
                   material=glossy(color="red"))) %>% 
  add_object(arrow(start = c(-1,1,0), end = c(1,1,0), tail_proportion = 0.75,
                   radius_top = 0.3, radius_tail=0.2,
                   material=glossy(color="red"))) %>% 
  add_object(sphere(y=5,z=5,x=2,material=light(intensity=30))) %>% 
  render_scene(clamp_value=10, samples=128)
}

if(run_documentation()) {
#We can also specify arrows via a midpoint and direction:
generate_studio(depth=-1) %>% 
  add_object(arrow(start = c(-1,-0.5,0), direction = c(0,0,1),
                   material=glossy(color="green"))) %>% 
  add_object(arrow(start = c(1,-0.5,0), direction = c(0,0,-1),
                   material=glossy(color="red"))) %>% 
  add_object(arrow(start = c(0,-0.5,1), direction = c(1,0,0),
                   material=glossy(color="yellow"))) %>% 
  add_object(arrow(start = c(0,-0.5,-1), direction = c(-1,0,0),
                   material=glossy(color="purple"))) %>% 
  add_object(sphere(y=5,z=5,x=2,material=light(intensity=30))) %>% 
  render_scene(clamp_value=10, samples=128, 
               lookfrom=c(0,5,10), lookat=c(0,-0.5,0), fov=16)
}

if(run_documentation()) {
#Plot a 3D vector field for a gravitational well:

r = 1.5
theta_vals = seq(0,2*pi,length.out = 16)[-16]
phi_vals = seq(0,pi,length.out = 16)[-16][-1]
arrow_list = list()
counter = 1
for(theta in theta_vals) {
  for(phi in phi_vals) {
    rval = c(r*sin(phi)*cos(theta),r*cos(phi),r*sin(phi)*sin(theta)) 
    arrow_list[[counter]] = arrow(rval, direction = -1/2*rval/sqrt(sum(rval*rval))^3,
                                  tail_proportion = 0.66, radius_top=0.03, radius_tail=0.01,
                                  material = diffuse(color="red"))
    counter = counter + 1
  }
}
vector_field = do.call(rbind,arrow_list)
sphere(material=diffuse(noise=1,color="blue",noisecolor="darkgreen")) %>% 
  add_object(vector_field) %>% 
  add_object(sphere(y=0,x=10,z=5,material=light(intensity=200))) %>% 
  render_scene(fov=20, ambient=TRUE, samples=128,
               backgroundlow="black",backgroundhigh="white") 
}