This adds some new JSON entries to custom levels so they can support
vanilla sky textures and the texture remapping tables, allowing for
proper textures on objects that use `generic`, like dark eco pools or
dying enemies.
The comments explain it in more detail, but the gist is:
For skies:
- `sky` needs to be a vanilla level that has sky textures.
- The alpha tpage (fourth entry in `tpages`) needs to be that vanilla
level's alpha tpage (if `tex_remap` is the same level as `sky`, this
will be handled automatically).
- The tpage needs to be added to the custom level `.gd` and to
`textures` in the JSON.
- In `level-info.gc`, `sky` needs to be `#t`, your level's mood needs to
call `update-mood-sky-texture` (the default mood, `update-mood-default`,
handles this as an example) and `sun-fade` needs to be nonzero for the
sun to show up.
For `generic` textures:
- `tex_remap` needs to be the name of a vanilla level.
- When using a vanilla level's remap table, you need to adhere to the
order of the files in that level's `.gd` in your own level.
- Code files are first.
- Then the tpages (in the order `tfrag`, `pris`, `shrub`, `alpha`,
`water`).
- Then the art groups.
- Lastly, the level file.
- The tpages need to be added to the `textures` in the JSON.
This only applies to the background for now:
- support for alpha for vertex colors in custom levels
- switch time of day palette generation from octree to k-d tree
- support for alpha masking in custom levels
- support for transparent textures
- support for envmap in custom levels
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Co-authored-by: water111 <awaterford1111445@gmail.com>