utilities.3d             package:lattice             R Documentation

Utility functions for 3-D plots

Description:

     These are (related to) the default panel functions for 'cloud' and
     'wireframe'.

Usage:

     ltransform3dMatrix(screen, R.mat)
     ltransform3dto3d(x, R.mat, dist)

Arguments:

       x: 'x' can be a numeric matrix with 3 rows for
          'ltransform3dto3d' 

  screen: list, as described in 'panel.cloud'

   R.mat: 4x4 transformation matrix in homogeneous coordinates

    dist: controls transformation to account for perspective viewing

Details:

     'ltransform3dMatrix' and 'ltransform3dto3d' are utility functions
     to help in computation of projections. These functions are used
     inside the panel functions for 'cloud' and 'wireframe'. They may
     be useful in user-defined panel functions as well.

     The first function takes a list of the form of the 'screen'
     argument in 'cloud' and 'wireframe' and a 'R.mat', a 4x4
     transformation matrix in homogeneous coordinates, to return a new
     4x4 transformation matrix that is the result of applying 'R.mat'
     followed by the rotations in 'screen'. The second function applies
     a 4x4 transformation matrix in homogeneous coordinates to a 3xn
     matrix representing points in 3-D space, and optionally does some
     perspective computations. (There has been no testing with
     non-trivial transformation matrices, and my knowledge of the
     homogeneous coordinate system is very limited, so there may be
     bugs here.)

Author(s):

     Deepayan Sarkar Deepayan.Sarkar@R-project.org

See Also:

     'cloud', 'panel.cloud'

