encode_gid / decode_gid pack atlas_index (8 bits), tile_id (20 bits), and
rotation (2 bits) into a single u32; gid == 0 is reserved as the empty-cell
sentinel. Lua 5.4 native bitwise operators used throughout.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Sprite-mode in draw_map:
- tilemap-tiles with texture atlas-id render via
engine.render.draw_sprite_transform with rotation pivot at tile center
- tiles without texture continue to render via draw_rect with color
(Phase 1 mode preserved)
Tile rotation:
- maps support an optional tile_rotations parallel array in the map
JSON with per-cell 90-degree rotation values (0/90/180/270)
- absent or nil entries default to 0 (no rotation)
- enables 9-segment tile reuse via rotation rather than per-orientation
sprites
New API:
- maps.load_textures(asset_aliases) resolves the current tilemap's
tile atlas-ids to texture-handles via the asset-lib indirection
(asset_aliases[tilemap.asset_pack] -> lib-id -> atlas.json lookup
per tile)
Schema additions:
- tilemap.asset_pack (alias-key, optional)
- tile.texture (atlas-id, optional)
- map.tile_rotations (parallel array, optional)
All existing Phase 1 color-only tilemaps render unchanged.
Pre-existing bug: split_namespaced_id used first-dot-split. For modules
with dotted IDs (e.g. lib-core.maps-test), this misclassified
'<dotted-module-id>.<tilemap-name>' as cross-lib reference.
Replaced with split_local_tilemap() that matches by exact current-
module-id prefix. Module-id can now have arbitrary dots.
Surfaced by P.3.1 reference test-module 'lib-core.maps-test' which
has a dotted module-id.
