e1ca95c0af
Add three static PAK-format decoders in the Bevy-free formats crate and present them in the explorer: - t8ad.rs: linear 32bpp A8R8G8B8 2D texture (UI/HUD art). Dims at 0x14/0x18, header size keyed by the type field @0x1c (container-safe). Decodes the ~85% RGBA variants; defers the rest (likely DXT) rather than misdecoding. - ratc.rs: nested resource bundle — lists named children by magic scan. - lsta.rs: sprite list — walks the inline T8aD frames. Viewer: PakContent gains T8ad/Lsta/Ratc, decoded off-thread and bounded by an 8M-texel per-entry cap; detail views show the texture, a sprite grid, and a child list with thumbnails. Decoded images carry a "colours unverified" note — channel-order/sRGB stays on the dynamic-RE backlog. Tests: 12 new unit + 3 real-disc (T8aD >=70% decode over the hangar pack, LSTA frames, RATC named children incl. a decodable T8aD). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
79 lines
2.4 KiB
Rust
79 lines
2.4 KiB
Rust
//! `LSTA` — a sprite list: a header followed by N inline [`T8aD`](crate::t8ad)
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//! frames concatenated back-to-back.
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//!
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//! A `count` lives at `@0x04`, but a few entries disagree with the actual frame
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//! count, so we walk by the `T8aD` magic instead (robust) and decode each frame
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//! from its slice up to the next frame (or end).
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use crate::t8ad::{self, T8adImage, T8AD_MAGIC};
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/// Magic at the start of an LSTA sprite list.
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pub const LSTA_MAGIC: [u8; 4] = *b"LSTA";
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/// Whether `bytes` is an LSTA list.
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pub fn is_lsta(bytes: &[u8]) -> bool {
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bytes.len() >= 4 && bytes[0..4] == LSTA_MAGIC
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}
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/// Decode all inline T8aD frames. Frames that don't decode (unsupported T8aD
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/// variant) are skipped. Returns `None` only for non-LSTA input.
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pub fn parse(bytes: &[u8]) -> Option<Vec<T8adImage>> {
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if !is_lsta(bytes) {
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return None;
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}
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// Offsets of each inline T8aD frame (search past the 4-byte magic).
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let mut offs = Vec::new();
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let mut i = 4;
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while i + 4 <= bytes.len() {
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if bytes[i..i + 4] == T8AD_MAGIC {
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offs.push(i);
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i += 4;
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} else {
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i += 1;
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}
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}
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let mut frames = Vec::with_capacity(offs.len());
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for (idx, &off) in offs.iter().enumerate() {
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let next = offs.get(idx + 1).copied().unwrap_or(bytes.len());
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if let Some(img) = t8ad::parse(&bytes[off..next]) {
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frames.push(img);
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}
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}
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Some(frames)
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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fn t8ad_frame(w: u32, h: u32) -> Vec<u8> {
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let mut b = vec![0u8; 64];
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b[0..4].copy_from_slice(&T8AD_MAGIC);
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b[0x14..0x18].copy_from_slice(&w.to_be_bytes());
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b[0x18..0x1c].copy_from_slice(&h.to_be_bytes());
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b[0x1c..0x20].copy_from_slice(&1u32.to_be_bytes());
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b.extend_from_slice(&vec![0x80u8; (w * h * 4) as usize]);
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b
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}
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#[test]
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fn walks_inline_frames() {
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let mut b = LSTA_MAGIC.to_vec();
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b.extend_from_slice(&2u32.to_be_bytes());
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b.extend_from_slice(&[0u8; 15]); // header remainder
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b.extend_from_slice(&t8ad_frame(4, 4));
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b.extend_from_slice(&t8ad_frame(2, 3));
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let frames = parse(&b).unwrap();
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assert_eq!(frames.len(), 2);
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assert_eq!((frames[0].width, frames[0].height), (4, 4));
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assert_eq!((frames[1].width, frames[1].height), (2, 3));
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}
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#[test]
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fn rejects_non_lsta() {
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assert!(parse(b"T8aD....").is_none());
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}
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}
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