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ASCIIMoon: The moon's phase live in ASCII art

(asciimoon.com)
268 points zayat | 2 comments | 01 Jul 25 10:53 UTC | HN request time: 0s | source
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SlowTao ◴[02 Jul 25 21:41 UTC] No.44449154[source]▶
While I love the ASCII art, yeah... thats not how the moon phase works. At half moon it should be exactly half occluded, so like it was cut in half, not just a weird circle cut out.

This is something that partially bothered me about GTA San Andreas on Ps2. They used the same trick as here but I would give them a pass because it was just a small detail on a large simulation on an already very limited system.

There are some great bones here on the site, just need to tweak the shadow and it can be a 10 out of 10.

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kingstnap ◴[02 Jul 25 22:11 UTC] No.44449386[source]▶
Yeah they seem to have drawn it as a dark circle going across for some reason.

But earth's shadows aren't what create moon phases IRL. The real moon phases are from the sun lighting the moon from different angles so this is just super weird.

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andreareina ◴[03 Jul 25 01:09 UTC] No.44450585[source]▶
Some reason probably being that it's easier
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1. kingstnap ◴[03 Jul 25 06:50 UTC] No.44452348[source]▶
The math isn't that bad if anyone wants to do it properly.

Assume y vertical and x horizontal and z out of the page.

The moon is a disk. x^2 + y^2 <= R^2

For all the points, calculate z = sqrt(R^2 - y^2 - x^2)

Let the vector v(theta) = <sin(theta), 0, cos(theta)> point to the Sun.

Points <x,y,z> • v(theta) >= 0 should be bright, The rest dim.

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2. JdeBP ◴[03 Jul 25 07:45 UTC] No.44452628[source]▶
Now achieve that when your implementation constraint is that you're using JavaScript to style a <div/> element. (-:

* https://github.com/Sean-93/asciimoon/blob/main/src/component...