feat(3d): Implement basic OBJ mesh asset pipeline

Added support for loading and rendering OBJ meshes.
- Updated asset_packer to parse .obj files into a binary format.
- Added MeshAsset and GetMeshAsset helper to asset_manager.
- Extended Object3D with mesh_asset_id and ObjectType::MESH.
- Implemented mesh rasterization pipeline in Renderer3D.
- Added a sample cube mesh and verified in test_3d_render.

1 files changed, 16 insertions, 0 deletions

diff --git a/src/util/asset_manager.h b/src/util/asset_manager.h
index a78447d..0c2cc63 100644
--- a/src/util/asset_manager.h
+++ b/src/util/asset_manager.h
@@ -39,6 +39,22 @@ struct TextureAsset {
   const uint8_t* pixels;
 };
 
+struct MeshVertex {
+  float p[3];
+  float n[3];
+  float u[2];
+};
+
+struct MeshAsset {
+  uint32_t num_vertices;
+  const MeshVertex* vertices;
+  uint32_t num_indices;
+  const uint32_t* indices;
+};
+
 // Helper to retrieve and parse a simple texture asset (from packer's
 // [w][h][pixels] format)
 TextureAsset GetTextureAsset(AssetId asset_id);
+
+// Helper to retrieve and parse a mesh asset (from packer's binary format)
+MeshAsset GetMeshAsset(AssetId asset_id);