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.

2 files changed, 118 insertions, 20 deletions

diff --git a/crates/render-demo/src/lib.rs b/crates/render-demo/src/lib.rs
index c5c72b5..c82e055 100644
--- a/crates/render-demo/src/lib.rs
+++ b/crates/render-demo/src/lib.rs
@@ -1,5 +1,7 @@
+use encoding_rs::WINDOWS_1251;
 use msh_core::{parse_model_payload, Model};
 use nres::{Archive, EntryRef};
+use std::fmt;
 use std::path::{Path, PathBuf};
 use texm::{decode_mip_rgba8, parse_texm};
 
@@ -22,6 +24,37 @@ pub enum Error {
     InvalidMaterial(String),
 }
 
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Nres(err) => write!(f, "{err}"),
+            Self::Msh(err) => write!(f, "{err}"),
+            Self::Texm(err) => write!(f, "{err}"),
+            Self::Io(err) => write!(f, "{err}"),
+            Self::NoMshEntries => write!(f, "archive does not contain .msh entries"),
+            Self::ModelNotFound(name) => write!(f, "model not found: {name}"),
+            Self::NoTexmEntries => write!(f, "archive does not contain Texm entries"),
+            Self::TextureNotFound(name) => write!(f, "texture not found: {name}"),
+            Self::MaterialNotFound(name) => write!(f, "material not found: {name}"),
+            Self::WearNotFound(name) => write!(f, "wear entry not found: {name}"),
+            Self::InvalidWear(reason) => write!(f, "invalid WEAR payload: {reason}"),
+            Self::InvalidMaterial(reason) => write!(f, "invalid MAT0 payload: {reason}"),
+        }
+    }
+}
+
+impl std::error::Error for Error {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        match self {
+            Self::Nres(err) => Some(err),
+            Self::Msh(err) => Some(err),
+            Self::Texm(err) => Some(err),
+            Self::Io(err) => Some(err),
+            _ => None,
+        }
+    }
+}
+
 impl From<nres::error::Error> for Error {
     fn from(value: nres::error::Error) -> Self {
         Self::Nres(value)
@@ -280,7 +313,7 @@ fn find_material_entry_with_fallback<'a>(
 }
 
 fn parse_wear_material_names(payload: &[u8]) -> Result<Vec<String>> {
-    let text = String::from_utf8_lossy(payload).replace('\r', "");
+    let text = decode_cp1251(payload).replace('\r', "");
     let mut lines = text.lines();
     let Some(first) = lines.next() else {
         return Err(Error::InvalidWear(String::from("WEAR payload is empty")));
@@ -360,9 +393,7 @@ fn parse_primary_texture_name_from_mat0(payload: &[u8], attr2: u32) -> Result<Op
             .iter()
             .position(|&b| b == 0)
             .unwrap_or(name_raw.len());
-        let name = String::from_utf8_lossy(&name_raw[..name_end])
-            .trim()
-            .to_string();
+        let name = decode_cp1251(&name_raw[..name_end]).trim().to_string();
         if !name.is_empty() {
             return Ok(Some(name));
         }
@@ -371,6 +402,11 @@ fn parse_primary_texture_name_from_mat0(payload: &[u8], attr2: u32) -> Result<Op
     Ok(None)
 }
 
+fn decode_cp1251(bytes: &[u8]) -> String {
+    let (decoded, _, _) = WINDOWS_1251.decode(bytes);
+    decoded.into_owned()
+}
+
 fn load_texture_from_archive_by_name(archive: &Archive, name: &str) -> Result<LoadedTexture> {
     let Some(id) = archive.find(name) else {
         return Err(Error::TextureNotFound(name.to_string()));
@@ -524,4 +560,45 @@ mod tests {
         assert!(texture.width > 0 && texture.height > 0);
         assert!(!texture.rgba8.is_empty());
     }
+
+    #[test]
+    fn parse_wear_material_names_parses_counted_lines() {
+        let payload = b"2\r\n0 MAT_A\r\n1 MAT_B\r\n";
+        let materials =
+            parse_wear_material_names(payload).expect("failed to parse valid WEAR payload");
+        assert_eq!(materials, vec!["MAT_A".to_string(), "MAT_B".to_string()]);
+    }
+
+    #[test]
+    fn parse_wear_material_names_rejects_invalid_payload() {
+        let payload = b"2\n0 ONLY_ONE\n";
+        assert!(matches!(
+            parse_wear_material_names(payload),
+            Err(Error::InvalidWear(_))
+        ));
+    }
+
+    #[test]
+    fn parse_primary_texture_name_from_mat0_respects_attr2_layout() {
+        let mut payload = vec![0u8; 4 + 10 + 34];
+        payload[0..2].copy_from_slice(&1u16.to_le_bytes()); // phase_count
+                                                            // attr2=4 adds 10 bytes before phase table
+        let name = b"TEX_MAIN";
+        payload[4 + 10 + 18..4 + 10 + 18 + name.len()].copy_from_slice(name);
+
+        let parsed = parse_primary_texture_name_from_mat0(&payload, 4)
+            .expect("failed to parse MAT0 payload with attr2=4");
+        assert_eq!(parsed, Some("TEX_MAIN".to_string()));
+    }
+
+    #[test]
+    fn parse_primary_texture_name_from_mat0_decodes_cp1251_bytes() {
+        let mut payload = vec![0u8; 4 + 34];
+        payload[0..2].copy_from_slice(&1u16.to_le_bytes()); // phase_count
+        payload[4 + 18] = 0xC0; // 'А' in CP1251
+
+        let parsed =
+            parse_primary_texture_name_from_mat0(&payload, 0).expect("failed to parse MAT0");
+        assert_eq!(parsed, Some("А".to_string()));
+    }
 }
diff --git a/crates/render-demo/src/main.rs b/crates/render-demo/src/main.rs
index bb826d5..8d309d1 100644
--- a/crates/render-demo/src/main.rs
+++ b/crates/render-demo/src/main.rs
@@ -11,6 +11,7 @@ struct Args {
     group: usize,
     width: u32,
     height: u32,
+    fov_deg: f32,
     capture: Option<PathBuf>,
     angle: Option<f32>,
     spin_rate: f32,
@@ -32,6 +33,7 @@ fn parse_args() -> Result<Args, String> {
     let mut group = 0usize;
     let mut width = 1280u32;
     let mut height = 720u32;
+    let mut fov_deg = 60.0f32;
     let mut capture = None;
     let mut angle = None;
     let mut spin_rate = 0.35f32;
@@ -94,6 +96,17 @@ fn parse_args() -> Result<Args, String> {
                     return Err(String::from("--height must be > 0"));
                 }
             }
+            "--fov" => {
+                let value = it
+                    .next()
+                    .ok_or_else(|| String::from("missing value for --fov"))?;
+                fov_deg = value
+                    .parse::<f32>()
+                    .map_err(|_| String::from("invalid --fov value"))?;
+                if !(1.0..=179.0).contains(&fov_deg) {
+                    return Err(String::from("--fov must be in range [1, 179]"));
+                }
+            }
             "--capture" => {
                 let value = it
                     .next()
@@ -163,6 +176,7 @@ fn parse_args() -> Result<Args, String> {
         group,
         width,
         height,
+        fov_deg,
         capture,
         angle,
         spin_rate,
@@ -176,7 +190,7 @@ fn parse_args() -> Result<Args, String> {
 
 fn print_help() {
     eprintln!(
-        "parkan-render-demo --archive <path> [--model <name.msh>] [--lod N] [--group N] [--width W] [--height H]"
+        "parkan-render-demo --archive <path> [--model <name.msh>] [--lod N] [--group N] [--width W] [--height H] [--fov DEG]"
     );
     eprintln!("                  [--capture <out.png>] [--angle RAD] [--spin-rate RAD_PER_SEC]");
     eprintln!("                  [--texture <name>] [--texture-archive <path>] [--material-archive <path>] [--wear <name.wea>] [--no-texture]");
@@ -202,7 +216,7 @@ fn run(args: Args) -> Result<(), String> {
     let loaded_model = load_model_with_name_from_archive(&args.archive, args.model.as_deref())
         .map_err(|err| {
             format!(
-                "failed to load model from archive {}: {err:?}",
+                "failed to load model from archive {}: {err}",
                 args.archive.display()
             )
         })?;
@@ -289,6 +303,7 @@ fn run(args: Args) -> Result<(), String> {
         vertex_data.push(vertex.uv0[0]);
         vertex_data.push(vertex.uv0[1]);
     }
+    let vertex_bytes = f32_slice_to_ne_bytes(&vertex_data);
 
     let gl = unsafe {
         glow::Context::from_loader_function(|name| video.gl_get_proc_address(name) as *const _)
@@ -306,11 +321,7 @@ fn run(args: Args) -> Result<(), String> {
     let vbo = unsafe { gl.create_buffer().map_err(|e| e.to_string())? };
     unsafe {
         gl.bind_buffer(glow::ARRAY_BUFFER, Some(vbo));
-        gl.buffer_data_u8_slice(
-            glow::ARRAY_BUFFER,
-            cast_slice_u8(&vertex_data),
-            glow::STATIC_DRAW,
-        );
+        gl.buffer_data_u8_slice(glow::ARRAY_BUFFER, &vertex_bytes, glow::STATIC_DRAW);
         gl.bind_buffer(glow::ARRAY_BUFFER, None);
     }
 
@@ -388,11 +399,9 @@ fn resolve_texture(args: &Args, model_name: &str) -> Result<Option<LoadedTexture
                 || args.material_archive.is_some()
                 || args.wear.is_some()
             {
-                Err(format!("failed to resolve texture: {err:?}"))
+                Err(format!("failed to resolve texture: {err}"))
             } else {
-                eprintln!(
-                    "warning: auto texture resolve failed ({err:?}), fallback to solid color"
-                );
+                eprintln!("warning: auto texture resolve failed ({err}), fallback to solid color");
                 Ok(None)
             }
         }
@@ -451,7 +460,14 @@ fn run_capture(
     capture_path: &Path,
 ) -> Result<(), String> {
     let angle = args.angle.unwrap_or(0.0);
-    let mvp = compute_mvp(args.width, args.height, center, camera_distance, angle);
+    let mvp = compute_mvp(
+        args.width,
+        args.height,
+        args.fov_deg,
+        center,
+        camera_distance,
+        angle,
+    );
     unsafe {
         draw_frame(
             gl,
@@ -515,7 +531,7 @@ fn run_interactive(
         let angle = args
             .angle
             .unwrap_or(start.elapsed().as_secs_f32() * args.spin_rate);
-        let mvp = compute_mvp(w, h, center, camera_distance, angle);
+        let mvp = compute_mvp(w, h, args.fov_deg, center, camera_distance, angle);
 
         unsafe {
             draw_frame(
@@ -543,12 +559,13 @@ fn run_interactive(
 fn compute_mvp(
     width: u32,
     height: u32,
+    fov_deg: f32,
     center: [f32; 3],
     camera_distance: f32,
     angle_rad: f32,
 ) -> [f32; 16] {
     let aspect = (width as f32 / (height.max(1) as f32)).max(0.01);
-    let proj = mat4_perspective(60.0_f32.to_radians(), aspect, 0.01, camera_distance * 10.0);
+    let proj = mat4_perspective(fov_deg.to_radians(), aspect, 0.01, camera_distance * 10.0);
     let view = mat4_translation(0.0, 0.0, -camera_distance);
     let center_shift = mat4_translation(-center[0], -center[1], -center[2]);
     let rot = mat4_rotation_y(angle_rad);
@@ -733,8 +750,12 @@ void main() {
     Ok(program)
 }
 
-fn cast_slice_u8<T>(slice: &[T]) -> &[u8] {
-    unsafe { std::slice::from_raw_parts(slice.as_ptr() as *const u8, std::mem::size_of_val(slice)) }
+fn f32_slice_to_ne_bytes(slice: &[f32]) -> Vec<u8> {
+    let mut out = Vec::with_capacity(slice.len().saturating_mul(std::mem::size_of::<f32>()));
+    for &value in slice {
+        out.extend_from_slice(&value.to_ne_bytes());
+    }
+    out
 }
 
 fn mat4_identity() -> [f32; 16] {