mesh3d: 3D Mesh objects

Description Usage Arguments Details Value See Also Examples

Description

3D triangle and quadrangle mesh object creation and a collection of sample objects.

Usage

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  qmesh3d(vertices, indices, homogeneous = TRUE, material = NULL, 
         normals = NULL, texcoords = NULL,
         meshColor = c("vertices", "edges", "faces", "legacy"))
  tmesh3d(vertices, indices, homogeneous = TRUE, material = NULL, 
         normals = NULL, texcoords = NULL,
         meshColor = c("vertices", "edges", "faces", "legacy"))
  
  cube3d(trans = identityMatrix(), ...)  
  tetrahedron3d(trans = identityMatrix(), ...)  
  octahedron3d(trans = identityMatrix(), ...)  
  icosahedron3d(trans = identityMatrix(), ...)
  dodecahedron3d(trans = identityMatrix(), ...)
  cuboctahedron3d(trans = identityMatrix(), ...)
  
  oh3d(trans = identityMatrix(), ...)    # an 'o' object
  
  dot3d(x, ...)   # draw dots at the vertices of an object
  ## S3 method for class 'mesh3d'
dot3d(x, ...,
                         front = "points", back = "points")
  wire3d(x, ...)  # draw a wireframe object
  ## S3 method for class 'mesh3d'
wire3d(x, ...,
                          front = "lines", back = "lines")
  shade3d(x, ...) # draw a shaded object
  ## S3 method for class 'mesh3d'
shade3d(x, override = TRUE, 
                           meshColor = c("vertices", "edges", "faces", "legacy"), 
                           texcoords = NULL, ...,
                           front = "filled", back = "filled")

Arguments

x

a mesh3d object (class qmesh3d or tmesh3d).

vertices

3- or 4-component vector of coordinates

indices

4-component vector of vertex indices

homogeneous

logical indicating if homogeneous (four component) coordinates are used.

material

material properties for later rendering

normals

normals at each vertex

texcoords

texture coordinates at each vertex

trans

transformation to apply to objects; see below for defaults

...

additional rendering parameters, or for dots3d and wire3d, parameters to pass to shade3d

override

should the parameters specified here override those stored in the object?

meshColor

how should colours be interpreted? See details below

front, back

Material properties for rendering.

Details

These functions create and work with mesh3d objects, which consist of a matrix of vertex coordinates together with a matrix of indices indicating which vertex is part of which face. Such objects may have triangular faces, planar quadrilateral faces, or both.

The sample objects optionally take a matrix transformation trans as an argument. This transformation is applied to all vertices of the default shape. The default is an identity transformation.

The "shape3d" class is a general class for shapes that can be plotted by dot3d, wire3d or shade3d.

The "mesh3d" class is a class of objects that form meshes: the vertices are in member vb, as a 3 or 4 by n matrix. Meshes with triangular faces will contain it, a 3 * n matrix giving the indices of the vertices in each face. Quad meshes will have vertex indices in ib, a 4 * n matrix. Individual meshes may have both types of faces.

The meshColor argument controls how material colours and textures are interpreted. This parameter was added in rgl version 0.100.1 (0.100.27 for dot3d, tmesh3d and qmesh3d; 0.102.19 for textures). Possible values are:

"vertices"

Colours and texture coordinates are applied by vertex, in the order they appear in the vb matrix.

"edges"

Colours and textures are applied to each edge: first to the 3 edges of each triangle in the it matrix, then the 4 edges of each quad in the ib matrix. This mode is only supported if both front and back materials are "lines".

"faces"

Colours and textures are applied to each face: first to the triangles in the it matrix, then to the quads in the ib matrix.

"legacy"

Colours and textures are applied in the same way as in rgl versions earlier than 0.100.1.

Unique partial matches of these values will be recognized.

If colours are specified but meshColor is not and options(rgl.meshColorWarning = TRUE), a warning will be given that their interpretation may have changed. In versions 0.100.1 to 0.100.26 of rgl, the default was to give the warning; now the default is for no warning.

Note that since version 0.102.10, meshColor = "edges" is only allowed when drawing lines (the wire3d default), and it may draw edges more than once. In general, if any rendering draws twice at the same location, which copy is visible depends on the order of drawing and the material3d("depth_test") setting.

Value

qmesh3d, cube3d, oh3d, tmesh3d, tetrahedron3d, octahedron3d, icosahedron3d and dodecahedron3d return objects of class c("mesh3d", "shape3d"). The first three of these are quad meshes, the rest are triangle meshes.

dot3d, wire3d, and shade3d are called for their side effect of drawing an object into the scene; they return an object ID (or vector of IDs, for some classes) invisibly.

See rgl.primitive for a discussion of texture coordinates.

See Also

r3d, par3d, shapelist3d for multiple shapes

Examples

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  # generate a quad mesh object

  vertices <- c( 
     -1.0, -1.0, 0, 1.0,
      1.0, -1.0, 0, 1.0,
      1.0,  1.0, 0, 1.0,
     -1.0,  1.0, 0, 1.0
  )
  indices <- c( 1, 2, 3, 4 )
  
  open3d()  
  wire3d( qmesh3d(vertices, indices) )
  
  # render 4 meshes vertically in the current view

  open3d()  
  bg3d("gray")
  l0 <- oh3d(tran = par3d("userMatrix"), color = "green" )
  shade3d( translate3d( l0, -6, 0, 0 ))
  l1 <- subdivision3d( l0 )
  shade3d( translate3d( l1 , -2, 0, 0 ), color = "red", override = FALSE )
  l2 <- subdivision3d( l1 )
  shade3d( translate3d( l2 , 2, 0, 0 ), color = "red", override = TRUE )
  l3 <- subdivision3d( l2 )
  shade3d( translate3d( l3 , 6, 0, 0 ), color = "red" )
  
  # render all of the Platonic solids
  open3d()
  shade3d( translate3d( tetrahedron3d(col = "red"), 0, 0, 0) )
  shade3d( translate3d( cube3d(col = "green"), 3, 0, 0) )
  shade3d( translate3d( octahedron3d(col = "blue"), 6, 0, 0) )
  shade3d( translate3d( dodecahedron3d(col = "cyan"), 9, 0, 0) )
  shade3d( translate3d( icosahedron3d(col = "magenta"), 12, 0, 0) )

rgl documentation built on Jan. 13, 2021, 3:25 p.m.