This would allow easy implementation of custom textures for moons.

Nice idea

I provided the texture in my pull request, though it might take some doing to get it so that you don't need *_phases.png for each moon.

What I'd think to do is, rather than drawing a celestial body onto the skybox then drawing the phase on top of it, you either combine the phase with the celestial body as a single sprite, then draw that sprite onto the skybox such that there's only one transparency, or generating *_phases.png assets as needed. If the mod generates the graphics itself, it will make adding celestial bodies easier. You may even be able to make phases inherent to Planet instead of Moon (though ringed or irregular planets might look a bit weird).

What I'd think to do is, rather than drawing a celestial body onto the skybox then drawing the phase on top of it, you either combine the phase with the celestial body as a single sprite, then draw that sprite onto the skybox such that there's only one transparency

Gonna be honest here, not even a clue where one would begin that with Minecraft.

or generating *_phases.png assets as needed

Or... it could just be a lot simpler and there would be one default file the game defaults to, no need to overcomplicate it.

Gonna be honest here, not even a clue where one would begin that with Minecraft.

That's the neat part. You use some sort of java image library or something. It might be simpler and easier to have one default file, at least in the short term, but it might be nice to have it so that, with only a single planet texture, it generates phases and halo phases (which just seems to be the same halo eight times anyway).

Gonna be honest here, not even a clue where one would begin that with Minecraft.

That's the neat part. You use some sort of java image library or something. It might be simpler and easier to have one default file, at least in the short term, but it might be nice to have it so that, with only a single planet texture, it generates phases and halo phases (which just seems to be the same halo eight times anyway).

The thing is, you don't render images in Minecraft. You call RenderSystem.setShaderTexture() and provide it with the ResourceLocation (path to the file) and RenderSystem does its own thing, no info related to what is on the image involved. The way more advanced rendering is achieved is by calling additional functions afterwards, like setting blending functions and shader properties. The image stays intact.

lol