split_tilesets.sh

#!/bin/bash
set -ex

source=scenes/tileset.tres
declare -A targets=(
 [tiles/bridges.tres]="tiles for bridges (and their shadows)"
 [tiles/elevation.tres]="cliff tiles (plain and mines)"
 [tiles/exterior_floors.tres]="grass, sand, and dirt tiles"
 [tiles/foam.tres]="foam tiles"
 [tiles/void_chromakey.tres]="chromakey Void texture"
 [tiles/water.tres]="water tiles"
)

declare -a heads

for target in "${!targets[@]}"
do
  desc="${targets[$target]}"
  git switch --detach main
  git mv "$source" "$target"
  git commit --no-verify \
    -m "Move $source to $target" \
    -m "Subsequent commits will delete all unrelated tiles from the copy, then
restore the source."
  git show "split-tileset:$target" > "$target"
  git add "$target"
  git commit --no-verify \
    -m "Remove unrelated tiles from $target" \
    -m "This removes all atlas sources except the $desc,
and all unrelated patterns & terrains."
  heads+=($(git rev-parse HEAD))
done


git switch --detach main
git merge --no-verify --no-ff "${heads[@]}" \
    -m "Split $source into separate tilesets"

# Now restore the original
git checkout main "$source"
git add "$source"
git commit --no-verify -m "Restore $source"