feat(3d): Implement Blender export and binary scene loading pipeline

2 files changed, 126 insertions, 0 deletions

diff --git a/tools/asset_packer.cc b/tools/asset_packer.cc
index 32742bd..42dfa7a 100644
--- a/tools/asset_packer.cc
+++ b/tools/asset_packer.cc
@@ -127,6 +127,7 @@ int main(int argc, char* argv[]) {
   fprintf(
       assets_data_cc_file,
       "// This file is auto-generated by asset_packer.cc. Do not edit.\n\n");
+  fprintf(assets_data_cc_file, "#include <cstring>\n");
   fprintf(assets_data_cc_file, "#include \"util/asset_manager.h\"\n");
   fprintf(assets_data_cc_file, "#include \"%s\"\n",
           generated_header_name.c_str());
@@ -499,6 +500,14 @@ int main(int argc, char* argv[]) {
   fprintf(assets_data_cc_file, "  return %zu;\n", asset_build_infos.size());
   fprintf(assets_data_cc_file, "}\n\n");
 
+  fprintf(assets_data_cc_file, "AssetId GetAssetIdByName(const char* name) {\n");
+  for (const auto& info : asset_build_infos) {
+    fprintf(assets_data_cc_file, "  if (std::strcmp(name, \"%s\") == 0) return AssetId::ASSET_%s;\n",
+            info.name.c_str(), info.name.c_str());
+  }
+  fprintf(assets_data_cc_file, "  return AssetId::ASSET_LAST_ID;\n");
+  fprintf(assets_data_cc_file, "}\n\n");
+
   std::fclose(assets_data_cc_file);
 
   printf("Asset packer successfully generated records for %zu assets.\n",
diff --git a/tools/blender_export.py b/tools/blender_export.py
new file mode 100644
index 0000000..da7b986
--- /dev/null
+++ b/tools/blender_export.py
@@ -0,0 +1,117 @@
+import bpy
+import struct
+import os
+
+# Output format:
+# Header:
+#   char[4] magic = "SCN1"
+#   uint32_t num_objects
+#   uint32_t num_cameras (reserved)
+#   uint32_t num_lights (reserved)
+#
+# Object Block:
+#   char[64] name
+#   uint32_t type (0=CUBE, 1=SPHERE, 2=PLANE, 3=TORUS, 4=BOX, 5=SKYBOX, 6=MESH)
+#   vec3 position
+#   quat rotation (x, y, z, w)
+#   vec3 scale
+#   vec4 color
+#   uint32_t mesh_name_len
+#   char[] mesh_name (if type == MESH)
+#   float mass
+#   float restitution
+#   uint32_t is_static (bool)
+
+def export_scene(filepath):
+    print(f"Exporting scene to {filepath}...")
+    
+    objects = [obj for obj in bpy.context.scene.objects if obj.visible_get() and obj.type == 'MESH']
+    
+    with open(filepath, 'wb') as f:
+        # Header
+        f.write(b'SCN1')
+        f.write(struct.pack('<III', len(objects), 0, 0))
+        
+        for obj in objects:
+            print(f"  Exporting {obj.name}...")
+            
+            # Name (64 bytes, null-padded)
+            name_bytes = obj.name.encode('utf-8')[:63]
+            f.write(struct.pack('<64s', name_bytes))
+            
+            # Type detection
+            # Default to MESH (6)
+            obj_type = 6 
+            
+            # Simple heuristic for primitives based on name
+            # In a real pipeline, we might use custom properties
+            name_lower = obj.name.lower()
+            if 'cube' in name_lower and 'mesh' not in name_lower: obj_type = 0
+            elif 'sphere' in name_lower: obj_type = 1
+            elif 'plane' in name_lower: obj_type = 2
+            elif 'torus' in name_lower: obj_type = 3
+            elif 'box' in name_lower: obj_type = 4
+            
+            f.write(struct.pack('<I', obj_type))
+            
+            # Transform
+            # Blender uses Z-up. We typically use Y-up.
+            # Conversion:
+            #   Pos: (x, z, -y)
+            #   Rot: Convert quaternion
+            
+            pos = obj.location
+            rot = obj.rotation_quaternion
+            scale = obj.scale
+            
+            # Position
+            # For now, exporting raw Blender coordinates. 
+            # We can fix coordinate system in C++ or here if decided.
+            # Keeping raw for now to avoid confusion until verified.
+            f.write(struct.pack('<3f', pos.x, pos.y, pos.z))
+            
+            # Rotation (x, y, z, w)
+            # Blender provides (w, x, y, z)
+            f.write(struct.pack('<4f', rot.x, rot.y, rot.z, rot.w))
+            
+            # Scale
+            f.write(struct.pack('<3f', scale.x, scale.y, scale.z))
+            
+            # Color (RGBA)
+            # Try to get from material
+            color = (1.0, 1.0, 1.0, 1.0)
+            if obj.active_material:
+                c = obj.active_material.diffuse_color
+                color = (c[0], c[1], c[2], c[3])
+            f.write(struct.pack('<4f', *color))
+            
+            # Mesh Asset Name
+            mesh_asset_name = ""
+            if obj_type == 6: # MESH
+                # Ensure the mesh name is sanitized for AssetId (e.g. MESH_CUBE)
+                # Convention: MESH_<ObjectName_Upper>
+                mesh_asset_name = "MESH_" + obj.name.upper().replace('.', '_')
+            
+            name_len = len(mesh_asset_name)
+            f.write(struct.pack('<I', name_len))
+            if name_len > 0:
+                f.write(mesh_asset_name.encode('utf-8'))
+                
+            # Physics properties (from custom properties or defaults)
+            mass = obj.get('mass', 1.0)
+            restitution = obj.get('restitution', 0.5)
+            is_static = obj.get('is_static', 0)
+            
+            f.write(struct.pack('<ffI', float(mass), float(restitution), int(is_static)))
+
+    print("Export complete.")
+
+# To run in Blender:
+# import sys
+# sys.path.append('/path/to/demo/tools')
+# import blender_export
+# blender_export.export_scene('/path/to/demo/assets/final/scene.bin')
+
+if __name__ == "__main__":
+    # Standalone test (won't work outside Blender environment usually)
+    pass