gf_plot_slice

this function is used to plot a slice of mesh/mesh_fem

# Calling Sequence

    function [hfaces, htube, hquiver, hmesh]=gf_plot_slice(sl,varargin)

## Description

This function is used to plot a slice of mesh/mesh_fem (see gf_slice).

The options are specified as pairs of 'option name'/'option value':

- data [] data to be plotted (one value per slice node)

- convex_data [] data to be plotted (one value per mesh convex)

- mesh 'auto' :

  - 'on' -> show the mesh (faces of edges)

  - 'off' -> ignore mesh

- mesh_edges 'on' show mesh edges ?

- mesh_edges_color [0.60 0.60 1] color of mesh edges

- mesh_edges_width 0.70 width of mesh edges

- mesh_slice_edges 'on' show edges of the slice ?

- mesh_slice_edges_color [0.70 0 0]

- mesh_slice_edges_width 0.50

- mesh_faces 'off' 'on' -> fill mesh faces (otherwise they are transparent)

- mesh_faces_color [0.75 0.75 0.75]

- pcolor 'on' if the field is scalar, a color plot of its values is plotted

- quiver 'on' if the field is vector, represent arrows

- quiver_density 50 density of arrows in quiver plot

- quiver_scale 1 density of arrows in quiver plot

- tube 'on' use tube plot for 'filar' (1D) parts of the slice

- tube_color 'red' color of tubes (ignored if 'data' is not empty and 'pcolor' is on)

- tube_radius '0.05 tube radius; you can use a constant, or a vector of nodal values

- showoptions 'on' display the list of options

The 'data' and 'convex_data' are mutually exclusive.

## Examples

Consider that you have a 3D mesh fem mf and a vector field U defined on this mesh fem, solution of the Stokes problem in a tank (see the demo demo_stokes_3D_tank_draw.m in the tests directory).

    scf();
    // use a nice colormap
    c = [0 0 1; 0 .5 1; 0 1 .5; 0 1 0; .5 1 0; 1 .5 0; 1 .4 0; 1 0 0; 1 .2 0; 1 .4 0; 1 .6 0; 1 .8 0];
    h = gcf();
    h.color_map = colormap(c);
    // slice the mesh with two half spaces, and take the boundary of the resulting quarter-cylinder
    sl = gf_slice(list('boundary',list('intersection',list('planar',+1,[0;0;0],[0;1;0]},...
                                  list('planar',+1,[0;0;0],[1;0;0]))),m,6);
    Usl = gf_compute(pde('mf_u'),U,'interpolate on', sl); // interpolate the solution on the slice
    // show the norm of the displacement on this slice
    gf_plot_slice(sl,'mesh','on','data',sqrt(sum(Usl.^2,1)),'mesh_slice_edges','off');

    // another slice: now we take the lower part of the mesh
    sl = gf_slice(list('boundary',list('intersection',list('planar',+1,[0;0;6],[0;0;-1]},...
                                  list('planar',+1,[0;0;0],[0;1;0]))),m,6);
    Usl = gf_compute(pde('mf_u'),U,'interpolate on', sl);
    gf_plot_slice(sl,'mesh','on','data',sqrt(sum(Usl.^2,1)),'mesh_slice_edges','off');

    // this slice contains the transparent mesh faces displayed on the picture
    sl2 = gf_slice(list('boundary',list('planar',+1,[0;0;0],[0;1;0])),...
                   m,6,_setdiff(all_faces',TOPfaces','rows')');
    gf_plot_slice(sl2,'mesh_faces','off','mesh','on','pcolor','off');

    // last step is to plot the streamlines
    hh = [1 5 9 12.5 16 19.5]; // vertical position of the different starting points of the streamlines
    H  = [zeros(2,length(hh));hh];

    // compute the streamlines
    tsl  = gf_slice('streamlines',pde('mf_u'),U,H);
    Utsl = gf_compute(pde('mf_u'),U,'interpolate on', tsl);

    // render them with "tube plot"
    [a,h] = gf_plot_slice(tsl,'mesh','off','tube_radius',.2,'tube_color','white');

## See Also

- gf_slice