Resumed to project. INIT

notes/02-asset_loader.md

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+# Asset Loader
+
+## Current state
+
+TGA loading is implemented in `client/src/assets.rs`. `Image::from_tga(path)` reads the file,
+parses the 18-byte header, skips the colormap block, and returns an `Image` — supporting
+type 1 (uncompressed) and type 9 (RLE) via the private `decode_rle()` function in the same
+module. `game.rs` uses it directly: `Image::from_tga("assets/tilesets/overworld.tga")`.
+
+`Image` also provides `to_tileset() -> Vec<[u8; 64]>`, which splits the image into 8×8
+tiles row-major. Every tile is emitted; tile ID is the flat row-major index into the Vec,
+so tiles are never skipped or reordered. (Transparency is a per-pixel concern handled at
+blit time by `blit_tile`, not by the splitter.)
+
+`AssetStore` (a named registry) is **not yet implemented**. Assets are currently loaded
+inline in `Game::start()`.
+
+## Goal
+
+Add an `AssetStore` so that game code can ask for an asset by name rather than loading
+files directly at the call site.
+
+## Design notes
+
+- `Image` struct: `width: u32`, `height: u32`, `pixels: Vec<u8>` — done.
+- A simple `AssetStore` could be a `HashMap<&'static str, Image>` loaded at startup.
+- No streaming needed — the whole game is small enough to load everything upfront in `start()`.
+- Palette index 0 is transparent when blitting sprites. This convention is enforced by
+  `blit_tile()` in `pixelhelper.rs`; the loader itself does not need to handle it.
+- Pixel assets are stored as flat `Vec<u8>` of palette indices, row-major, width × height bytes.
+- Future: consider embedding assets with `include_bytes!` to produce a single binary.
+
+## Open questions
+
+- Should `AssetStore` hold pre-split tilesets too, or just raw `Image` values?