clipMesh: Clip a mesh

In MeshesTools: Some Tools for 3D Meshes

Clip a mesh

Description

Clip a mesh to the volume bounded by another mesh.

Usage

clipMesh(mesh, clipper, clipVolume = TRUE, normals = FALSE)

Arguments

mesh	a mesh given either as a list containing (at least) the fields vertices and faces, otherwise a rgl mesh (i.e. a mesh3d object)
clipper	a mesh given either as a list containing (at least) the fields vertices and faces, otherwise a rgl mesh (i.e. a mesh3d object)
clipVolume	Boolean, whether the clipping has to be done on the volume bounded by mesh rather than on its surface (i.e. mesh will be kept closed if it is closed)
normals	Boolean, whether to compute the vertex normals of the output mesh

Value

A triangle mesh of class cgalMesh (see Mesh for details).

Note

The clipping mesh (clipper) must be closed.

Examples

# cube clipped to sphere
library(MeshesTools)
library(rgl)
mesh    <- cube3d()
clipper <- sphereMesh(r= sqrt(2))
clippedMesh <- clipMesh(mesh, clipper)
open3d(windowRect = c(50, 50, 562, 562))
view3d(zoom = 0.9)
shade3d(toRGL(clippedMesh), color = "purple")

# Togliatti surface clipped to a ball ####
library(rmarchingcubes)
library(rgl)
library(MeshesTools)

# Togliatti surface equation: f(x,y,z) = 0
f <- function(x, y, z) {
  64*(x-1) *
    (x^4 - 4*x^3 - 10*x^2*y^2 - 4*x^2 + 16*x - 20*x*y^2 + 5*y^4 + 16 - 20*y^2) - 
    5*sqrt(5-sqrt(5))*(2*z - sqrt(5-sqrt(5))) * 
    (4*(x^2 + y^2 - z^2) + (1 + 3*sqrt(5)))^2
}

# grid
n <- 200L
x <- y <- seq(-5, 5, length.out = n)
z <- seq(-4, 4, length.out = n)
Grid <- expand.grid(X = x, Y = y, Z = z)
# calculate voxel
voxel <- array(with(Grid, f(X, Y, Z)), dim = c(n, n, n))
# calculate isosurface
contour_shape <- contour3d(
  griddata = voxel, level = 0, x = x, y = y, z = z
)
# make rgl mesh (plotted later)
mesh <- tmesh3d(
  vertices = t(contour_shape[["vertices"]]),
  indices  = t(contour_shape[["triangles"]]),
  normals  = contour_shape[["normals"]],
  homogeneous = FALSE
)

# clip to sphere of radius 4.8
clipper <- sphereMesh(r = 4.8)
clippedMesh <- clipMesh(mesh, clipper, clipVolume = FALSE, normals = TRUE)

# plot
open3d(windowRect = c(50, 50, 950, 500))
mfrow3d(1L, 2L)
view3d(0, -70, zoom = 0.8)
shade3d(mesh, color = "firebrick")
next3d()
view3d(0, -70, zoom = 0.8)
shade3d(toRGL(clippedMesh), color = "firebrick")

MeshesTools documentation built on Oct. 29, 2022, 9:05 a.m.