Added radius data for the Sun, Moon, and remaining planets.
Test the raytracer for all other bodies except the Earth and Sun.
There is a problem with Pluto that I still need to figure out.
Fixed an issue in the doxygen-to-markdown translator I wrote
(hydrogen.js): it did not handle when one #define referred
to another #define. Created a more generic markdown expansion
that works in all cases, and creates embedded hyperlinks.
Refactored the Jupiter imager to be a generic planet imager.
Added support for drawing an image of Venus.
Verified that its extreme crescent phase looks correct
for the current date.
I will add radius constants to astronomy.h for each body I support.
The raytracer now includes the option -s (without a numeric
spin angle on the command line) to automatically calculate
the spin angle needed to bring the planet's north pole
exactly upward in the generated image.
Improved the way I create the rotation matrix that
aims the virtual camera at Jupiter. The camera still
aims exactly at Jupiter, but this time it defaults
to having the left/right pixel direction aligning
with the Earth's equator. By experiment, I can spin
the longitudinal camera axis by -10 degrees and get
a good fit with Jupiter's equatorial plane. I will
adjust this more exactly in a future commit.
Now the raytracer requires the user to pass in
both the pixel width and pixel height on the command line.
This allows for generating non-square images, which will
be necessary for the general case of imaging the moons
with respect to the planet.
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.
