1 files changed, 113 insertions, 0 deletions
diff --git a/crates/render-demo/src/lib.rs b/crates/render-demo/src/lib.rs
new file mode 100644
index 0000000..4c73c09
--- /dev/null
+++ b/crates/render-demo/src/lib.rs
@@ -0,0 +1,113 @@
+use msh_core::{parse_model_payload, Model};
+use nres::Archive;
+use std::path::Path;
+
+#[derive(Debug)]
+pub enum Error {
+    Nres(nres::error::Error),
+    Msh(msh_core::error::Error),
+    NoMshEntries,
+    ModelNotFound(String),
+}
+
+impl From<nres::error::Error> for Error {
+    fn from(value: nres::error::Error) -> Self {
+        Self::Nres(value)
+    }
+}
+
+impl From<msh_core::error::Error> for Error {
+    fn from(value: msh_core::error::Error) -> Self {
+        Self::Msh(value)
+    }
+}
+
+pub type Result<T> = core::result::Result<T, Error>;
+
+pub fn load_model_from_archive(path: &Path, model_name: Option<&str>) -> Result<Model> {
+    let archive = Archive::open_path(path)?;
+    let mut msh_entries = Vec::new();
+    for entry in archive.entries() {
+        if entry.meta.name.to_ascii_lowercase().ends_with(".msh") {
+            msh_entries.push((entry.id, entry.meta.name.clone()));
+        }
+    }
+    if msh_entries.is_empty() {
+        return Err(Error::NoMshEntries);
+    }
+
+    let target_id = if let Some(name) = model_name {
+        msh_entries
+            .iter()
+            .find(|(_, n)| n.eq_ignore_ascii_case(name))
+            .map(|(id, _)| *id)
+            .ok_or_else(|| Error::ModelNotFound(name.to_string()))?
+    } else {
+        msh_entries[0].0
+    };
+
+    let payload = archive.read(target_id)?;
+    Ok(parse_model_payload(payload.as_slice())?)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::fs;
+    use std::path::{Path, PathBuf};
+
+    fn collect_files_recursive(root: &Path, out: &mut Vec<PathBuf>) {
+        let Ok(entries) = fs::read_dir(root) else {
+            return;
+        };
+        for entry in entries.flatten() {
+            let path = entry.path();
+            if path.is_dir() {
+                collect_files_recursive(&path, out);
+            } else if path.is_file() {
+                out.push(path);
+            }
+        }
+    }
+
+    fn archive_with_msh() -> Option<PathBuf> {
+        let root = Path::new(env!("CARGO_MANIFEST_DIR"))
+            .join("..")
+            .join("..")
+            .join("testdata");
+        let mut files = Vec::new();
+        collect_files_recursive(&root, &mut files);
+        files.sort();
+        for path in files {
+            let Ok(bytes) = fs::read(&path) else {
+                continue;
+            };
+            if bytes.get(0..4) != Some(b"NRes") {
+                continue;
+            }
+            let Ok(archive) = Archive::open_path(&path) else {
+                continue;
+            };
+            if archive
+                .entries()
+                .any(|entry| entry.meta.name.to_ascii_lowercase().ends_with(".msh"))
+            {
+                return Some(path);
+            }
+        }
+        None
+    }
+
+    #[test]
+    fn load_model_from_real_archive() {
+        let Some(path) = archive_with_msh() else {
+            eprintln!("skipping load_model_from_real_archive: no .msh archives in testdata");
+            return;
+        };
+        let model = load_model_from_archive(&path, None)
+            .unwrap_or_else(|err| panic!("failed to load model from {}: {err:?}", path.display()));
+        assert!(model.node_count > 0);
+        assert!(!model.positions.is_empty());
+        assert!(!model.indices.is_empty());
+    }
+}