## LaTeX forum ⇒ Graphics, Figures & Tables ⇒ Stereographic map projections for drawing ellipsoids

Information and discussion about graphics, figures & tables in LaTeX documents.
matsun
Posts: 4
Joined: Tue Sep 05, 2017 1:21 pm

### Stereographic map projections for drawing ellipsoids

I would need to plot with Tikz some 3D drawings of ellipsoids: I am trying to adapt the excellent code provided by Tomas M. Trzeciak for plotting spheres based on stereographic and cylindrical map projections.

Original code: http://www.texample.net/tikz/examples/map-projections/

I started to have a look at the functions but I do not know Tex very well.. Is there anyone skilled in math and Tex who's willing to help me?

I started to check the command `\LongitudePlane`:
`\newcommand\LongitudePlane[3][current plane]{%  \pgfmathsinandcos\sinEl\cosEl{#2} % elevation  \pgfmathsinandcos\sint\cost{#3} % azimuth  \tikzset{#1/.estyle={cm={\cost,\sint*\sinEl,0,\cosEl,(0,0)}}}}`

but I am already lost.. What does `[current plane]` stand for? What is the output of this function?

Thank you for the support!

Tags:

Stefan Kottwitz
Posts: 8541
Joined: Mon Mar 10, 2008 9:44 pm
Location: Hamburg, Germany
Contact:
Hi matsun,

welcome to the forum!

`current plane` is an parameter of this function. This function/macro is called several times with various planes, that are: `xzplane`, `pzplane`, `qzplane`, and `equator`.

`cm` may stand for "coordinate matrix", just a quick guess, as I could not look deeper into the code yet.

Stefan