Add Plane UV Mapping to Mesh

Applies a planar UV mapping to a mesh based on a given direction and set of U/V vectors. If full_mesh_bbox is true, the UV mapping is scaled based on the bounding box of the entire mesh. If false, each shape's bounding box is used. One of direction/u/v must be NULL and will be calculated from the others.

add_plane_uv_mesh(
  mesh,
  direction = c(0, 1, 0),
  u = NULL,
  v = NULL,
  override_existing = FALSE,
  full_mesh_bbox = TRUE
)

Arguments

mesh

The mesh to which the UV mapping will be applied.

direction

Default c(0, 1, 0). A vector specifying the direction for UV mapping. If not specified and u/v are both specified, this will be ignored.

u

Default NULL. A vector specifying the u direction.

v

Default NULL. A vector specifying the v direction.

override_existing

Default FALSE. Specifies whether existing UV coordinates should be overridden.

full_mesh_bbox

Default TRUE. Specifies whether the full mesh's bounding box is used for UV mapping.

Value

Modified mesh with added UV mapping.

Examples

if(run_documentation()) {
#Let's construct a mesh from the volcano dataset
#Build the vertex matrix
vertex_list = list()
counter = 1
for(i in 1:nrow(volcano)) {
  for(j in 1:ncol(volcano)) {
    vertex_list[[counter]] = matrix(c(j,volcano[i,j]/3,i), ncol=3)
    counter = counter + 1
  }
}
vertices = do.call(rbind,vertex_list)

#Build the index matrix
index_list = list()
counter = 0
for(i in 1:(nrow(volcano)-1)) {
  for(j in 1:(ncol(volcano)-1)) {
    index_list[[counter+1]] = matrix(c(counter,counter+ncol(volcano),counter+1,
                                       counter+ncol(volcano),counter+ncol(volcano)+1,counter + 1),
                                     nrow=2, ncol=3, byrow=TRUE)
    counter = counter + 1
  }
  counter = counter + 1
}
indices = do.call("rbind",index_list)

#Create a checkerboard image
create_checkerboard_texture = function(filename, n = 16) {
  old_par = par(no.readonly = TRUE)
  on.exit(par(old_par))
  plot.new()
  par(mar = c(0, 0, 0, 0))
  checkerboard = matrix(c(1, 0), nrow = n+1, ncol = n)
  png(filename, width = 800, height = 800)
  image(1:(n+1), 1:n, checkerboard, col = c("dodgerblue", "red"),
        axes = FALSE, xlab = "", ylab = "")
  dev.off()
}
checkerboard_file = tempfile(fileext = ".png")
create_checkerboard_texture(checkerboard_file)

#Construct the mesh
volc_mesh = construct_mesh(vertices = vertices, indices = indices,
                           material = material_list(type="phong", diffuse="darkred",
                                                    ambient = "darkred", ambient_intensity=0.2))


#Set the direction so that the checkerboard will be mapped to the surface like a carpet
uv = add_plane_uv_mesh(volc_mesh, direction=c(0,200,0), u = c(1,0,0))
uv = set_material(uv, texture_location = checkerboard_file,
                  ambient = "white", ambient_intensity=0.1)
#Rasterize the scene
rasterize_scene(center_mesh(uv), lookfrom=c(200,200,200),fov=0,width=1200,height=1200,
                light_info = directional_light(c(0,1,1)) |>
                  add_light(directional_light(c(1,1,-1))),ortho_dimensions=c(120,120))


#Set the direction so that the checkerboard will be mapped directly at the camera
uv = add_plane_uv_mesh(volc_mesh, direction=c(200,200,200), v = c(-1,1,-1))
uv = set_material(uv, texture_location = checkerboard_file,
                  ambient = "white", ambient_intensity=0.1)
#Rasterize the scene
rasterize_scene(center_mesh(uv), lookfrom=c(200,200,200),fov=0,width=1200,height=1200,
                light_info = directional_light(c(0,1,1)) |>
                add_light(directional_light(c(1,1,-1))), ortho_dimensions=c(120,120))
}
#> Setting `lookat` to: c(0.00, 0.00, 0.00)

#> Setting `lookat` to: c(0.00, 0.00, 0.00)