basic implementation for isosurface, isocolors, isonormals

[Thomas Treichl]

David Bateman schrieb:
> Ok, well it was a little bit harder than I thought for a few reasons
> 
> 1) gnuplot's depth order pm3d code only works for a single surface and 
> so a set of patches that need to be depth sorted need to be plotted with 
> a single splot command
> 2) The gnuplot binary file format doesn't support "index" for splot and 
> so constraint 1) means the data has to be written as ASCII
> 3) As pm3d uses the color palette, any fixed color patches need to have 
> their color added to the colormap, and then the other things plotted 
> with the colormap need to be treated carefully..
> 
> In any  case I committed the attached patch that appears to work fine 
> for all the tests I ran with the gnuplot CVS version. One issue I have 
> is with gnuplot 4.2.4 I see the attached for the command 
> "demo('patch',6); colorbar" for the X11 terminal. This appears to be a 
> gnuplot bug as it works for other terminals like png, eps, etc and it 
> works for the CVS version of gnuplot.. Should I care about this bug?

Hi David,

thanks for this work. However, I've some smaller problems running the new 
__patch__.m command. The function "field" you're using in lines 37, 39, 42 and 
further is undefined to me. Is this another function file you are using but 
maybe forgot to check in?

Next, if I try to run any of the demos from the help texts of isosurface or 
isocolors then none does work anymore because of an error that looks like this, 
for example

   octave:22> N = 15;    ## Increase number of vertices in each direction
   octave:23> iso = .4;  ## Change isovalue to .1 to display a sphere
   octave:24> lin = linspace (0, 2, N);
   octave:25> [x, y, z] = meshgrid (lin, lin, lin);
   octave:26> c = abs ((x-.5).^2 + (y-.5).^2 + (z-.5).^2);
   octave:27> figure (); ## Open another figure window
   octave:28>
   octave:28> subplot (2, 2, 1); view (-38, 20);
   octave:29> [f, v] = isosurface (x, y, z, c, iso);
   octave:30> p = patch ("Faces", f, "Vertices", v, "EdgeColor", "none");
   error: A(I): Index exceeds matrix dimension.
   error: called from:
   error:   /Users/Thomas/Development/octave/scripts/plot/__patch__.m at
   line 220, column 4
   error:   /Users/Thomas/Development/octave/scripts/plot/__patch__.m at
   line 138, column 12
   error: `tmp' undefined near line 59 column 14
   error: called from:
   error:   /Users/Thomas/Development/octave/scripts/plot/patch.m at line 59,
   column 12

Any ideas? Thanks,

   Thomas