From 680b8123fa00ad4861c2e6a75b68673fa1df8ce0 Mon Sep 17 00:00:00 2001
From: HampusM <hampus@hampusmat.com>
Date: Tue, 15 Sep 2026 13:21:52 +0200
Subject: fix(engine): treat file paths in obj & mtl assets as relative to file

---
 engine/src/material/asset.rs | 13 ++++++++++---
 engine/src/model/asset.rs    | 13 ++++++++++---
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/engine/src/material/asset.rs b/engine/src/material/asset.rs
index b210154..31d4ce5 100644
--- a/engine/src/material/asset.rs
+++ b/engine/src/material/asset.rs
@@ -28,6 +28,10 @@ fn import_wavefront_mtl_asset(
     _settings: Option<&'_ Settings>,
 ) -> Result<(), Error>
 {
+    let parent_path = path
+        .parent()
+        .ok_or_else(|| Error::InvalidPath(path.to_path_buf()))?;
+
     let named_materials = crate::file_format::wavefront::mtl::parse(
         &read_to_string(path)
             .map_err(|err| Error::ReadFailed(err, path.to_path_buf()))?,
@@ -46,19 +50,19 @@ fn import_wavefront_mtl_asset(
 
         if let Some(ambient_map) = material.ambient_map {
             material_builder = material_builder.ambient_map(
-                asset_submitter.submit_load_other(ambient_map.path.as_path()),
+                asset_submitter.submit_load_other(parent_path.join(&ambient_map.path)),
             );
         }
 
         if let Some(diffuse_map) = material.diffuse_map {
             material_builder = material_builder.diffuse_map(
-                asset_submitter.submit_load_other(diffuse_map.path.as_path()),
+                asset_submitter.submit_load_other(parent_path.join(&diffuse_map.path)),
             );
         }
 
         if let Some(specular_map) = material.specular_map {
             material_builder = material_builder.specular_map(
-                asset_submitter.submit_load_other(specular_map.path.as_path()),
+                asset_submitter.submit_load_other(parent_path.join(&specular_map.path)),
             );
         }
 
@@ -81,6 +85,9 @@ fn import_wavefront_mtl_asset(
 #[derive(Debug, thiserror::Error)]
 enum Error
 {
+    #[error("Invalid path '{}'", .0.display())]
+    InvalidPath(PathBuf),
+
     #[error("Failed to read file {}", .1.display())]
     ReadFailed(#[source] std::io::Error, PathBuf),
 
diff --git a/engine/src/model/asset.rs b/engine/src/model/asset.rs
index dd9e60b..69a06aa 100644
--- a/engine/src/model/asset.rs
+++ b/engine/src/model/asset.rs
@@ -20,6 +20,10 @@ fn import_wavefront_obj_asset(
     _settings: Option<&'_ Settings>,
 ) -> Result<(), Error>
 {
+    let parent_path = path
+        .parent()
+        .ok_or_else(|| Error::InvalidPath(path.to_path_buf()))?;
+
     let obj = crate::file_format::wavefront::obj::parse(
         &read_to_string(path)
             .map_err(|err| Error::ReadFailed(err, path.to_path_buf()))?,
@@ -29,11 +33,11 @@ fn import_wavefront_obj_asset(
 
     let mesh_asset = asset_submitter.submit_store_named("mesh", mesh);
 
-    let mut material_asset_map_assets = Vec::with_capacity(obj.mtl_libs.iter().count());
+    let mut material_asset_map_assets = Vec::with_capacity(obj.mtl_libs.len());
 
     for mtl_lib_path in &obj.mtl_libs {
-        let mtl_lib_asset =
-            asset_submitter.submit_load_other::<MaterialAssetMap>(mtl_lib_path.as_path());
+        let mtl_lib_asset = asset_submitter
+            .submit_load_other::<MaterialAssetMap>(parent_path.join(mtl_lib_path));
 
         material_asset_map_assets.push(mtl_lib_asset);
     }
@@ -56,6 +60,9 @@ fn import_wavefront_obj_asset(
 #[derive(Debug, thiserror::Error)]
 enum Error
 {
+    #[error("Invalid path '{}'", .0.display())]
+    InvalidPath(PathBuf),
+
     #[error("Failed to read file {}", .1.display())]
     ReadFailed(#[source] std::io::Error, PathBuf),
 
-- 
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