rgl: subdivision3d – R documentation

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subdivision3d

Subdivide a mesh

Description

The subdivision surface algorithm divides and refines (deforms) a given mesh recursively to certain degree (depth). The mesh3d algorithm consists of two stages: divide and deform. The divide step generates for each triangle or quad four new triangles or quads, the deform step drags the points (refinement step).

Usage

subdivision3d( x,  ...)
  ## S3 method for class 'mesh3d'
subdivision3d( x, depth = 1, normalize = FALSE, deform = TRUE, ... )
  divide.mesh3d(mesh,  vb = mesh$vb, ib = mesh$ib, it = mesh$it )
  normalize.mesh3d(mesh)
  deform.mesh3d(mesh, vb = mesh$vb, ib = mesh$ib, it = mesh$it )

Arguments

`x`	3d geometry mesh
`mesh`	3d geometry mesh
`depth`	recursion depth
`normalize`	normalize mesh3d coordinates after division if `deform` is `TRUE`
`deform`	deform mesh
`it`	indices for triangular faces
`ib`	indices for quad faces
`vb`	matrix of vertices: 4 x n matrix (rows x, y, z, h) or equivalent vector, where h indicates scaling of each plotted quad
`...`	other arguments (unused)

Details

subdivision3d takes a mesh object and replaces each triangle or quad with 4 new ones by adding vertices half-way along the edges (and one in the centre of a quad). The positions of the vertices are deformed so that the resulting surface is smoother than the original. These operations are repeated depth times.

The other functions do the individual steps of the subdivision. divide.mesh3d adds the extra vertices. deform.mesh3d does the smoothing by replacing each vertex with the average of each of its neighbours. normalize.mesh3d normalizes the homogeneous coordinates, by setting the 4th coordinate to 1. (The 4th coordinate is used as a weight in the deform step.)

Examples

open3d()
  shade3d( subdivision3d( cube3d(), depth = 3 ), color = "red", alpha = 0.5 )

rgl

3D Visualization Using OpenGL

v0.106.8

GPL

Authors

Duncan Murdoch [aut, cre], Daniel Adler [aut], Oleg Nenadic [ctb], Simon Urbanek [ctb], Ming Chen [ctb], Albrecht Gebhardt [ctb], Ben Bolker [ctb], Gabor Csardi [ctb], Adam Strzelecki [ctb], Alexander Senger [ctb], The R Core Team [ctb, cph], Dirk Eddelbuettel [ctb], The authors of Shiny [cph], The authors of knitr [cph], Jeroen Ooms [ctb], Yohann Demont [ctb], Joshua Ulrich [ctb], Xavier Fernandez i Marin [ctb], George Helffrich [ctb], Ivan Krylov [ctb]

Initial release