utilities.3d             package:lattice             R Documentation

_U_t_i_l_i_t_y _f_u_n_c_t_i_o_n_s _f_o_r _3-_D _p_l_o_t_s

_D_e_s_c_r_i_p_t_i_o_n:

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

_U_s_a_g_e:

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

_A_r_g_u_m_e_n_t_s:

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

  screen: list, as described in 'cloud'

   R.mat: 4x4 transformation matrix in homogeneous coordinates

    dist: controls transformation to account for perspective viewing

_D_e_t_a_i_l_s:

     '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.)

_A_u_t_h_o_r(_s):

     Deepayan Sarkar Deepayan.Sarkar@R-project.org

_S_e_e _A_l_s_o:

     'cloud', 'panel.cloud'

