Now that I have eliminated refraction and reflection
from the astronomy raytracer, there is no need for an
Optics class that represents matte, gloss, and index
of refraction.
I had lots of problems with using AU as my scale units.
By changing to 10000*km units, the vector equation solver
works correctly again, and I actually get an image of Jupiter
and its moons. However, it does not match the test photo:
Ganymede does not appear close to the planet, nor is there
a shadow of it on the planet. I will have to debug that
separately.
Starting to work through adaptation of existing
raytracer code to generate geometrically accurate
images of Jupiter and its moons. Not yet working,
but I believe I am at least aiming the camera in
the right direction.
The documentation for the Python function `SearchAltitude`
was missing a mention of the `altitude` parameter.
I searched for similar mistakes in Python, C#, and C,
having just completed the same exercise in the JavaScript code.
I also found several places where extraneous newlines
between the parameter documentation caused the Markdown
to be rendered incorrectly.
Added documentation about the missing `date` parameter
to the `Elongation` function in the JavaScript version.
I reviewed all the other JavaScript functions to make sure there
were no other similar mistakes with parameters or return types.
Along the way, I discovered and fixed some other issues:
Fixed miscellaneous typos in the documentation.
Consistently refer to enumeration values like `Body.Earth`
instead of strings like `"Earth"`. I want to encourage
use of the enumerations because they make type-checking easier,
especially for TypeScript code.
Reworked `AstroTime` parameters to `FlexibleDateTime` parameters
in all exported functions. This is completely backward-compatible,
and allows callers more flexibility with passing `AstroTime`,
`Date`, or numeric day values.
Now that Microsoft has officially released .NET 6,
I have upgraded the C# version of Astronomy Engine to use it.
No source code changes were needed. I just bumped the
version number in the project files, and targeted .NET 6
in the GitHub Actions continuous integration tests.
Fixed some obsolete wording in generate/README.md.
I used Cassini's Laws to derive an approximate solution
to the Moon's rotation axis. The error is on the order of
5 arcminutes. I still need to correct for physical libration.
I also need to find test data for the Moon's prime meridian
so that I can implement the spin angle calculation.
(I could use test data for all the planets' spins, for that matter.)
In Windows I am running Python 3.7.8.
For some reason, it fails to write Unicode Greek letters
I use in the Markdown documentation unless I explicitly
specify to use utf-8 encoding. I thought that was the default,
because it works fine in Linux running 3.9.2.
I'm not sure whether the issue is due to Windows or
to a change in the Python version. Regardless, I am
explicitly specifying the file encoding to make the
documentation translator I wrote (pydown.py) work.
This issue affected maintainers (mostly me) only.
Developers who are using Astronomy Engine do not need
to worry about this.
Running the source generator on Windows was broken because
I forgot to copy a step over from the Linux build that
prevents building tutorial pages in the master branch.
I didn't notice this until now because makedoc.bat also
had a bug where it detected an error but did not stop
execution... it just kept going and made it hard to
notice something was wrong.
I don't think it's a good idea to imply that the body constants
are always going to be consecutive, or that it makes sense to
iterate over them. The caller needs to understand the body enough
to know which operations are allowed and which aren't.
So I removed the constants MIN_BODY and MAX_BODY.
Calculate the vector that points in the direction
of the body's north pole.
The unit test now checks for excessive angle
between the expected north pole vector and the
calculated north pole vector.
I'm starting to implement formulas from the IAU 2015 report:
https://astropedia.astrogeology.usgs.gov/download/Docs/WGCCRE/WGCCRE2015reprint.pdf
This is a work in progress. The unit test is partially finished.
The C function Astronomy_RotationAxis() works only for the Sun and Mercury.
I want to also return a rotation matrix that reports the rotating
frame in a way more suited to graphics work. I will add this to
the type astro_axis_t later.
I am starting to work on calculation of the north pole
axes of various solar system bodies. Here I include a reference
source document, along with some test data, all described by
the README.md file.
Compare state vectors with the initial states used
to integrate the DE405 ephemeris.
This is just yet another confidence check that calculations
are correct.
When building Astronomy Engine for publication,
I was disabling generation of C documentation by default,
because I used to have issues getting deterministic output
in the CI tests (GitHub Actions). Now I have reason to believe
it will work reliably, so I am turning on C docs generation
by default.
If this fails the CI test, I will have to make the CI test
explicitly disable this step until I figure out how to fix it.
Otherwise (and preferably) the CI test will ensure that the
published C documentation is always up to date, and will fail
the build if there are any issues generating the docs.
I also had forgotten to enable installing dependencies for
my custom tool `hydrogen` in the Windows build. I added a fix
for that.
For now, I'm keeping beta/unfinished website and tutorial stuff
outside the master branch to reduce confusion for newcomers.
It will stay in the `tutorials` branch for any ongoing development.
If we finish it and make it ready for public use, then I will
bring it back into `master`.
Updated the `makedoc` script to gracefully skip steps
involving tutorials or website if they are absent.
Also, we were not installing packages needed for `hydrogen`
to generate C documentation. This broke document generation
on freshly-cloned repos.
I noticed on a freshly-cloned Astronomy Engine on Windows,
I started getting JavaScript test failures. The problem was the
script generate/test.js had an inconsistent way of reading text
from files and splitting it into lines. Some of the tests
did not account for \r\n line endings in Windows text files.
So I created a unified approach: a new function ReadLines
that works correctly for Linux and Windows, regardless
of the variant line endings.
This may not work on Mac OS, but I don't have an easy
way of testing that myself. But at least now I can fix
issues like that in one place.
I'm trying to make it easier for first-time visitors to
this project to find the source code and documentation
to get started quickly. Moved directories that are only
used by contributors (mostly myself) out of the root
and into the 'generate' directory where they are less
distracting.
