Add gallery example for grdview

[liamtoney]

Description of proposed changes

Add an example use of grdview() to the gallery. Serves as an example for #433, as well as a refresher for me. 😝

Reminders

• Run make format and make check to make sure the code follows the style guide.
• Add tests for new features or tests that would have caught the bug that you're fixing.
• Add new public functions/methods/classes to doc/api/index.rst.
• Write detailed docstrings for all functions/methods.
• If adding new functionality, add an example to docstrings or tutorials.

[liamtoney]

Two minor comments on this:

1. I didn't actually preview the ReST of the docstring. Do we have the math extension? Otherwise the :math: directive won't render properly.

2. I tried to illuminate the surface, but I='+' gave a flat image with shading rather than an illuminated 3-D surface.

[weiji14]

1. I didn't actually preview the ReST of the docstring. Do we have the math extension? Otherwise the :math: directive won't render properly.

It might be tough for Scipy Sprint folks to preview the documentation locally, unless they've set up a PyGMT environment, instructions are at https://github.com/GenericMappingTools/pygmt/blob/master/CONTRIBUTING.md#documentation if anyone needs them.

Luckily we've got #344, which reminds me, I'll send you an email to invite you as an owner on the Vercel gmt team, since you're part of @GenericMappingTools/python now. Anyways, preview is at https://pygmt-git-fork-liamtoney-grdview-gallery.gmt.now.sh/gallery/grid/grdview_surface.html#plotting-a-surface, or you can click on the "View deployment" button

2. I tried to illuminate the surface, but I='+' gave a flat image with shading rather than an illuminated 3-D surface.

Haven't tried illumination with grdview before, maybe try with debug mode on using V="d"?

[liamtoney]

Anyways, you can preview things at https://pygmt-git-fork-liamtoney-grdview-gallery.gmt.now.sh/gallery/grid/grdview_surface.html#plotting-a-surface.

That is really nifty!

Haven't tried illumination with grdview before, maybe try with debug mode on using V="d"?

Didn't see anything obvious in the console output. Will have to table for later, it looks alright as is!

[liamtoney]

Didn't see anything obvious in the console output. Will have to table for later, it looks alright as is!

I was able to re-create the code in pure GMT, and the shading performs as expected, so it's a PyGMT grid I/O issue I think. I'll make an issue.

Edit: I think this issue is the same as #364, so I'll just comment there.

[seisman]

Looks good to me.

[seisman]

@weiji14 is the one implementing the grdview() functions. Any comments?

[liamtoney]

Whoops. I saw your approval and merged. Apologies if that was premature.

[seisman]

It's fine. We can fix it later if @weiji14 wants more.

[weiji14]

Oops, missed it by a few minutes. I actually really like this Ackley function example, definitely better than anything I could have come up with!

Aside from a few extra inline comments, I think it's fine as is. We can add them in when the shading works in GMT 6.1 😉

[liamtoney]

We can add them in when the shading works in GMT 6.1 😉

Yes the shaded version looks quite nice so I'd like to update this example once we get to 6.1!