[Octave-patch-tracker] [patch #9859] missing functions: stream2, stream3, streamline

[Hg200]

Follow-up Comment #5, patch #9859 (project octave):

Thank you very much for the thorough code review and especially for pointing
out to the resize method. In the attached patch you will find:

* completion with suggested changes (endif, ~->!, spaces etc) 
* added error exit on complex data input (as pointing to complex transpose)
* one sentence on streamtube color
* fix copyright / it is not necessary to mention my name in the docu
* cameraviewanglemode set to manual in streamtube demo

In CFD post-processing it is common practice not to change the size of an
object as it is rotated and viewed from different angles. The two questionable
statements freeze the current view settings and set the modes to manual. It
looks like it does work as well if you just set the FOV to manual


set (gca, 'cameraviewanglemode', 'manual');


But from my side we can also remove the line completely in order to keep the
demo as simple as possible (it is not so important for a demo).

To your screenshots: Here it looks exactly the same. This artifact is caused
when too many vertices are passed to the line () or plot3 () command. You can
run the following MWE and then run it again, where N is reduced to 1000, and
look for the differences in the plot output.


N = 20000;
r = linspace (1, 50, N);
phi = linspace (0, 20*2*pi(), N);
x = r.*cos (phi);
y = r.*sin (phi);
z = 20*sin (phi);
line ('xdata', x, 'ydata', y, 'zdata', z, 'color', 'r');
axis equal;
view (3);


I can do a fix in streamline.m. For example, we could pass only every N-th
vertex to the line () command. However, then the documentation of line () must
contain information about the maximum allowable number of vertices to create a
nice plot. Probably a better way would be to make a direct fix in the code of
line (but requires knowledge about what causes the rendering problem) because
this "feature" could be also beneficial for other programs. What do you think?

(file #47956)
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File name: patch_streamline-20191201.patch Size:45 KB
   
<https://savannah.gnu.org/file/patch_streamline-20191201.patch?file_id=47956>



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