feat(render-core): add default UV scale and refactor UV mapping logic

- Introduced a constant `DEFAULT_UV_SCALE` for UV scaling.
- Refactored UV mapping in `build_render_mesh` to use the new constant.
- Simplified `compute_bounds` functions by extracting common logic into `compute_bounds_impl`.

test(render-core): add tests for rendering with empty and multi-node models

- Added tests to verify behavior when building render meshes from models with no slots and multiple nodes.
- Ensured UV scaling is correctly applied in tests.

feat(render-demo): add FOV argument and improve error handling

- Added a `--fov` command-line argument to set the field of view.
- Enhanced error messages for texture resolution failures.
- Updated MVP computation to use the new FOV parameter.

fix(rsli): improve error handling in LZH decompression

- Added checks to prevent out-of-bounds access in LZH decoding logic.

refactor(texm): streamline texture parsing and decoding tests

- Created a helper function `build_texm_payload` for constructing test payloads.
- Added tests for various texture formats including RGB565, RGB556, ARGB4444, and Luminance Alpha.
- Improved error handling for invalid TEXM headers and mip bounds.

4 files changed, 188 insertions, 57 deletions

diff --git a/crates/texm/Cargo.toml b/crates/texm/Cargo.toml
index 7085293..216bb44 100644
--- a/crates/texm/Cargo.toml
+++ b/crates/texm/Cargo.toml
@@ -3,5 +3,5 @@ name = "texm"
 version = "0.1.0"
 edition = "2021"
 
-[dependencies]
+[dev-dependencies]
 nres = { path = "../nres" }
diff --git a/crates/texm/src/error.rs b/crates/texm/src/error.rs
index 38e32ca..90d618d 100644
--- a/crates/texm/src/error.rs
+++ b/crates/texm/src/error.rs
@@ -1,6 +1,7 @@
 use core::fmt;
 
 #[derive(Debug)]
+#[non_exhaustive]
 pub enum Error {
     HeaderTooSmall {
         size: usize,
diff --git a/crates/texm/src/lib.rs b/crates/texm/src/lib.rs
index 5d8b594..7a166f3 100644
--- a/crates/texm/src/lib.rs
+++ b/crates/texm/src/lib.rs
@@ -36,6 +36,7 @@ impl PixelFormat {
         match self {
             Self::Indexed8 => 1,
             Self::Rgb565 | Self::Rgb556 | Self::Argb4444 | Self::LuminanceAlpha88 => 2,
+            // Parkan stores format 888 as 32-bit RGBX in texture payloads.
             Self::Rgb888 | Self::Argb8888 => 4,
         }
     }
@@ -173,14 +174,8 @@ pub fn parse_texm(payload: &[u8]) -> Result<Texture> {
             offset: level_offset,
             size: level_size,
         });
-        w = w.max(1) >> 1;
-        h = h.max(1) >> 1;
-        if w == 0 {
-            w = 1;
-        }
-        if h == 0 {
-            h = 1;
-        }
+        w = (w >> 1).max(1);
+        h = (h >> 1).max(1);
     }
 
     let page_rects = parse_page_tail(payload, offset)?;
@@ -240,7 +235,8 @@ pub fn decode_mip_rgba8(texture: &Texture, payload: &[u8], mip_index: usize) ->
                     break;
                 }
                 let poff = usize::from(index).saturating_mul(4);
-                if poff + 3 >= palette.len() {
+                // Keep this form to accept the last palette item (index 255).
+                if poff + 4 > palette.len() {
                     continue;
                 }
                 let out = i.saturating_mul(4);
diff --git a/crates/texm/src/tests.rs b/crates/texm/src/tests.rs
index 3d990bf..ba8aeeb 100644
--- a/crates/texm/src/tests.rs
+++ b/crates/texm/src/tests.rs
@@ -35,6 +35,36 @@ fn nres_test_files() -> Vec<PathBuf> {
         .collect()
 }
 
+fn build_texm_payload(
+    width: u32,
+    height: u32,
+    format_raw: u32,
+    flags5: u32,
+    palette: Option<[u8; 1024]>,
+    mip_levels: &[&[u8]],
+) -> Vec<u8> {
+    let mut payload = Vec::new();
+    payload.extend_from_slice(&TEXM_MAGIC.to_le_bytes());
+    payload.extend_from_slice(&width.to_le_bytes());
+    payload.extend_from_slice(&height.to_le_bytes());
+    payload.extend_from_slice(
+        &u32::try_from(mip_levels.len())
+            .expect("mip level count overflow in test")
+            .to_le_bytes(),
+    );
+    payload.extend_from_slice(&0u32.to_le_bytes()); // flags4
+    payload.extend_from_slice(&flags5.to_le_bytes());
+    payload.extend_from_slice(&0u32.to_le_bytes()); // unk6
+    payload.extend_from_slice(&format_raw.to_le_bytes());
+    if let Some(palette) = palette {
+        payload.extend_from_slice(&palette);
+    }
+    for level in mip_levels {
+        payload.extend_from_slice(level);
+    }
+    payload
+}
+
 #[test]
 fn texm_parse_all_game_textures() {
     let archives = nres_test_files();
@@ -97,16 +127,7 @@ fn texm_parse_all_game_textures() {
 
 #[test]
 fn texm_parse_minimal_argb8888_no_page() {
-    let mut payload = Vec::new();
-    payload.extend_from_slice(&TEXM_MAGIC.to_le_bytes());
-    payload.extend_from_slice(&1u32.to_le_bytes()); // width
-    payload.extend_from_slice(&1u32.to_le_bytes()); // height
-    payload.extend_from_slice(&1u32.to_le_bytes()); // mip_count
-    payload.extend_from_slice(&0u32.to_le_bytes()); // flags4
-    payload.extend_from_slice(&0u32.to_le_bytes()); // flags5
-    payload.extend_from_slice(&0u32.to_le_bytes()); // unk6
-    payload.extend_from_slice(&8888u32.to_le_bytes()); // format
-    payload.extend_from_slice(&[1, 2, 3, 4]); // one pixel
+    let payload = build_texm_payload(1, 1, 8888, 0, None, &[&[1, 2, 3, 4]]);
 
     let parsed = parse_texm(&payload).expect("failed to parse minimal texm");
     assert_eq!(parsed.header.width, 1);
@@ -117,17 +138,7 @@ fn texm_parse_minimal_argb8888_no_page() {
 
 #[test]
 fn texm_decode_minimal_argb8888_no_page() {
-    let mut payload = Vec::new();
-    payload.extend_from_slice(&TEXM_MAGIC.to_le_bytes());
-    payload.extend_from_slice(&1u32.to_le_bytes()); // width
-    payload.extend_from_slice(&1u32.to_le_bytes()); // height
-    payload.extend_from_slice(&1u32.to_le_bytes()); // mip_count
-    payload.extend_from_slice(&0u32.to_le_bytes()); // flags4
-    payload.extend_from_slice(&0u32.to_le_bytes()); // flags5
-    payload.extend_from_slice(&0u32.to_le_bytes()); // unk6
-    payload.extend_from_slice(&8888u32.to_le_bytes()); // format
-    payload.extend_from_slice(&[0x40, 0x11, 0x22, 0x33]); // A,R,G,B in little-endian order
-
+    let payload = build_texm_payload(1, 1, 8888, 0, None, &[&[0x40, 0x11, 0x22, 0x33]]);
     let parsed = parse_texm(&payload).expect("failed to parse minimal texm");
     let decoded = decode_mip_rgba8(&parsed, &payload, 0).expect("failed to decode mip");
     assert_eq!(decoded.width, 1);
@@ -136,18 +147,54 @@ fn texm_decode_minimal_argb8888_no_page() {
 }
 
 #[test]
+fn texm_decode_rgb565() {
+    let word = 0xFFE0u16; // r=31 g=63 b=0
+    let payload = build_texm_payload(1, 1, 565, 0, None, &[&word.to_le_bytes()]);
+    let parsed = parse_texm(&payload).expect("failed to parse rgb565 texm");
+    let decoded = decode_mip_rgba8(&parsed, &payload, 0).expect("failed to decode rgb565 texm");
+    assert_eq!(decoded.rgba8, vec![255, 255, 0, 255]);
+}
+
+#[test]
+fn texm_decode_rgb556() {
+    let word = 0xF800u16; // r=31 g=0 b=0
+    let payload = build_texm_payload(1, 1, 556, 0, None, &[&word.to_le_bytes()]);
+    let parsed = parse_texm(&payload).expect("failed to parse rgb556 texm");
+    let decoded = decode_mip_rgba8(&parsed, &payload, 0).expect("failed to decode rgb556 texm");
+    assert_eq!(decoded.rgba8, vec![255, 0, 0, 255]);
+}
+
+#[test]
+fn texm_decode_argb4444() {
+    let word = 0xF12Eu16; // a=F r=1 g=2 b=E
+    let payload = build_texm_payload(1, 1, 4444, 0, None, &[&word.to_le_bytes()]);
+    let parsed = parse_texm(&payload).expect("failed to parse argb4444 texm");
+    let decoded = decode_mip_rgba8(&parsed, &payload, 0).expect("failed to decode argb4444 texm");
+    assert_eq!(decoded.rgba8, vec![17, 34, 238, 255]);
+}
+
+#[test]
+fn texm_decode_luminance_alpha88() {
+    let word = 0x7F40u16; // luminance=0x7F alpha=0x40
+    let payload = build_texm_payload(1, 1, 88, 0, None, &[&word.to_le_bytes()]);
+    let parsed = parse_texm(&payload).expect("failed to parse la88 texm");
+    let decoded = decode_mip_rgba8(&parsed, &payload, 0).expect("failed to decode la88 texm");
+    assert_eq!(decoded.rgba8, vec![0x7F, 0x7F, 0x7F, 0x40]);
+}
+
+#[test]
+fn texm_decode_rgb888x() {
+    let payload = build_texm_payload(1, 1, 888, 0, None, &[&[0x11, 0x22, 0x33, 0x99]]);
+    let parsed = parse_texm(&payload).expect("failed to parse rgb888 texm");
+    let decoded = decode_mip_rgba8(&parsed, &payload, 0).expect("failed to decode rgb888 texm");
+    assert_eq!(decoded.rgba8, vec![0x11, 0x22, 0x33, 255]);
+}
+
+#[test]
 fn texm_parse_indexed_with_page_chunk() {
-    let mut payload = Vec::new();
-    payload.extend_from_slice(&TEXM_MAGIC.to_le_bytes());
-    payload.extend_from_slice(&2u32.to_le_bytes()); // width
-    payload.extend_from_slice(&2u32.to_le_bytes()); // height
-    payload.extend_from_slice(&1u32.to_le_bytes()); // mip_count
-    payload.extend_from_slice(&0u32.to_le_bytes()); // flags4
-    payload.extend_from_slice(&0u32.to_le_bytes()); // flags5
-    payload.extend_from_slice(&0u32.to_le_bytes()); // unk6
-    payload.extend_from_slice(&0u32.to_le_bytes()); // format indexed8
-    payload.extend_from_slice(&[0u8; 1024]); // palette
-    payload.extend_from_slice(&[1, 2, 3, 4]); // pixels
+    let mut palette = [0u8; 1024];
+    palette[4..8].copy_from_slice(&[10, 20, 30, 255]);
+    let mut payload = build_texm_payload(2, 2, 0, 0, Some(palette), &[&[1, 1, 1, 1]]);
     payload.extend_from_slice(&PAGE_MAGIC.to_le_bytes());
     payload.extend_from_slice(&1u32.to_le_bytes()); // rect_count
     payload.extend_from_slice(&0i16.to_le_bytes()); // x
@@ -170,26 +217,113 @@ fn texm_parse_indexed_with_page_chunk() {
 }
 
 #[test]
-fn texm_decode_indexed_with_palette() {
-    let mut payload = Vec::new();
-    payload.extend_from_slice(&TEXM_MAGIC.to_le_bytes());
-    payload.extend_from_slice(&2u32.to_le_bytes()); // width
-    payload.extend_from_slice(&1u32.to_le_bytes()); // height
-    payload.extend_from_slice(&1u32.to_le_bytes()); // mip_count
-    payload.extend_from_slice(&0u32.to_le_bytes()); // flags4
-    payload.extend_from_slice(&0u32.to_le_bytes()); // flags5
-    payload.extend_from_slice(&0u32.to_le_bytes()); // unk6
-    payload.extend_from_slice(&0u32.to_le_bytes()); // format indexed8
-
+fn texm_decode_indexed_with_palette_last_entry() {
     let mut palette = [0u8; 1024];
     palette[4..8].copy_from_slice(&[10, 20, 30, 255]); // index 1
     palette[8..12].copy_from_slice(&[40, 50, 60, 200]); // index 2
-    payload.extend_from_slice(&palette);
-    payload.extend_from_slice(&[1u8, 2u8]); // two pixels
+    palette[1020..1024].copy_from_slice(&[1, 2, 3, 4]); // index 255 (last)
+    let payload = build_texm_payload(3, 1, 0, 0, Some(palette), &[&[1u8, 2u8, 255u8]]);
 
     let parsed = parse_texm(&payload).expect("failed to parse indexed texm");
     let decoded = decode_mip_rgba8(&parsed, &payload, 0).expect("failed to decode indexed texm");
-    assert_eq!(decoded.width, 2);
+    assert_eq!(decoded.width, 3);
     assert_eq!(decoded.height, 1);
-    assert_eq!(decoded.rgba8, vec![10, 20, 30, 255, 40, 50, 60, 200]);
+    assert_eq!(
+        decoded.rgba8,
+        vec![10, 20, 30, 255, 40, 50, 60, 200, 1, 2, 3, 4]
+    );
+}
+
+#[test]
+fn texm_parse_multi_mip_offsets() {
+    let mip0 = [0x10u8; 32]; // 4*2*4
+    let mip1 = [0x20u8; 8]; // 2*1*4
+    let mip2 = [0x30u8; 4]; // 1*1*4
+    let payload = build_texm_payload(4, 2, 8888, 0, None, &[&mip0, &mip1, &mip2]);
+
+    let parsed = parse_texm(&payload).expect("failed to parse multi-mip texm");
+    assert_eq!(parsed.header.mip_count, 3);
+    assert_eq!(parsed.mip_levels.len(), 3);
+    assert_eq!(
+        parsed.mip_levels,
+        vec![
+            MipLevel {
+                width: 4,
+                height: 2,
+                offset: 32,
+                size: 32
+            },
+            MipLevel {
+                width: 2,
+                height: 1,
+                offset: 64,
+                size: 8
+            },
+            MipLevel {
+                width: 1,
+                height: 1,
+                offset: 72,
+                size: 4
+            },
+        ]
+    );
+}
+
+#[test]
+fn texm_preserves_flags5_for_mip_skip_metadata() {
+    let payload = build_texm_payload(1, 1, 8888, 0x0000_00A5, None, &[&[0, 0, 0, 0]]);
+    let parsed = parse_texm(&payload).expect("failed to parse texm");
+    assert_eq!(parsed.header.flags5, 0x0000_00A5);
+}
+
+#[test]
+fn texm_errors_for_invalid_header_values() {
+    let mut bad_magic = build_texm_payload(1, 1, 8888, 0, None, &[&[0, 0, 0, 0]]);
+    bad_magic[0..4].copy_from_slice(&0u32.to_le_bytes());
+    assert!(matches!(
+        parse_texm(&bad_magic),
+        Err(Error::InvalidMagic { .. })
+    ));
+
+    let zero_dims = build_texm_payload(0, 1, 8888, 0, None, &[&[]]);
+    assert!(matches!(
+        parse_texm(&zero_dims),
+        Err(Error::InvalidDimensions { .. })
+    ));
+
+    let mut bad_mips = build_texm_payload(1, 1, 8888, 0, None, &[&[0, 0, 0, 0]]);
+    bad_mips[12..16].copy_from_slice(&0u32.to_le_bytes());
+    assert!(matches!(
+        parse_texm(&bad_mips),
+        Err(Error::InvalidMipCount { .. })
+    ));
+
+    let bad_format = build_texm_payload(1, 1, 12345, 0, None, &[&[0, 0, 0, 0]]);
+    assert!(matches!(
+        parse_texm(&bad_format),
+        Err(Error::UnknownFormat { .. })
+    ));
+}
+
+#[test]
+fn texm_errors_for_page_chunk_and_mip_bounds() {
+    let mut bad_page = build_texm_payload(1, 1, 8888, 0, None, &[&[0, 0, 0, 0]]);
+    bad_page.extend_from_slice(b"X");
+    assert!(matches!(
+        parse_texm(&bad_page),
+        Err(Error::InvalidPageSize { .. })
+    ));
+
+    let payload = build_texm_payload(1, 1, 8888, 0, None, &[&[1, 2, 3, 4]]);
+    let parsed = parse_texm(&payload).expect("failed to parse valid texm");
+    assert!(matches!(
+        decode_mip_rgba8(&parsed, &payload, 7),
+        Err(Error::MipIndexOutOfRange { .. })
+    ));
+
+    let truncated = &payload[..payload.len() - 1];
+    assert!(matches!(
+        decode_mip_rgba8(&parsed, truncated, 0),
+        Err(Error::MipDataOutOfBounds { .. })
+    ));
 }