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, 12 insertions, 0 deletions

diff --git a/src/3d/renderer.h b/src/3d/renderer.h
index db86b72..5caf19b 100644
--- a/src/3d/renderer.h
+++ b/src/3d/renderer.h
@@ -8,6 +8,7 @@
 #include "3d/scene.h"
 #include "3d/bvh.h"
 #include "gpu/gpu.h"
+#include <map>
 #include <vector>
 
 #if !defined(STRIP_ALL)
@@ -65,11 +66,19 @@ class Renderer3D {
   void SetBvhEnabled(bool enabled) { bvh_enabled_ = enabled; }
 
  private:
+  struct MeshGpuData {
+    WGPUBuffer vertex_buffer;
+    WGPUBuffer index_buffer;
+    uint32_t num_indices;
+  };
+
   void create_pipeline();
   WGPURenderPipeline create_pipeline_impl(bool use_bvh);
+  void create_mesh_pipeline();
   void create_skybox_pipeline();
   void create_default_resources();
   void update_uniforms(const Scene& scene, const Camera& camera, float time);
+  const MeshGpuData* get_or_create_mesh(AssetId asset_id);
 
   WGPUDevice device_ = nullptr;
   WGPUQueue queue_ = nullptr;
@@ -78,6 +87,7 @@ class Renderer3D {
   WGPURenderPipeline pipeline_ = nullptr;        // BVH enabled
   WGPURenderPipeline pipeline_no_bvh_ = nullptr; // BVH disabled
   WGPUBindGroup bind_group_ = nullptr;
+  WGPURenderPipeline mesh_pipeline_ = nullptr;
   WGPURenderPipeline skybox_pipeline_ = nullptr;
   WGPUBindGroup skybox_bind_group_ = nullptr;
   WGPUBuffer global_uniform_buffer_ = nullptr;
@@ -87,6 +97,8 @@ class Renderer3D {
   BVH cpu_bvh_; // Keep a CPU-side copy for building/uploading
   bool bvh_enabled_ = true;
 
+  std::map<AssetId, MeshGpuData> mesh_cache_;
+
   WGPUTextureView noise_texture_view_ = nullptr;
   WGPUTextureView sky_texture_view_ = nullptr;
   WGPUSampler default_sampler_ = nullptr;