Space Planets

[FabianHummel]

Idea

While the player is in space, I need to render planets with the correct size / rotation and translation. I think of these following options which all have different advantages and disadvantages:

1. Create a 3D planet model (basically a sphere, duh) with a fixed texture (different texture-presets like Orange-Desert, Green-Nature, planets with mixed biomes, etc...). Advantage: this approach is the most "vanilla", because it doesn't primarily use shaders for rendering the actual shape. However, a sphere is rather difficult to model with Minecraft's constraints, even without the 22.5° limitation.

2. Create a 2D billboard planet that changes the texture based on the direction the player is looking at. Maybe, the planet can be procedurally textured using a shader, but I probably can't pass enough parameters to create a complex texture.

3. Use SDFs to create a perfect 3D sphere and pair it with a procedural texture for the most immersion. However, similar to the billboard option, I probably don't have a way to procedurally texture the object. Maybe I find a way to paint the planet in the post processing shader? Then I could pass different planet textures with varying quality and colors.

Regardless of which option I'll use, planets definitely require a Halo-effect and must interact with the sunlight to create an immersive experience and use either a very high-resolution or even a procedural texture.

[FabianHummel]

I'll try to use https://github.com/godlander/objmc to convert a sphere model with high resolution texture to an entity. This way, I can move and rotate the planet to anywhere I want and benefit from interpolated translation as well. It should also be relatively easy to create the desired lighting effects.

[FabianHummel]

Objmc officially works! It was a bit hard to set up, because there were no examples really, and there were some minor issues with updating it to 1.21.11 + combining it with existing shader code.

Credits: NASA (https://science.nasa.gov/resource/earth-3d-model/)

[FabianHummel]

Objmc turns out to be a bit problematic, especially rotation

The autorotate feature seems to only work on a single axis and is very jittery, so I can't use it.

I could use the color channels for rotation, but this takes up all three parameters, so I won't be able to add the sun direction for atmospheric lighting and custom day night cycles.

However, I don't actually need to individually modify the rotation of each planet: I could simply use the player's rotation and calculate each planet's rotation based on that. On top of that I will also apply some relative rotation for the day night cycle based on the global GameTime. Translation can also be applied directly in the shader code, because I know all required parameters like the player's absolute position (CameraBlockPos + CameraOffset)