From d08bd8ff81344e02649cc3bed02b95d895a66bcf Mon Sep 17 00:00:00 2001
From: Frederico Linhares <fred@linhares.blue>
Date: Tue, 11 Mar 2025 14:40:03 -0300
Subject: feat Add header to static mesh files

---
 src/blu_cat/com/binary_reader.hpp |   8 +++----
 src/blu_cat/gra/static_mesh.cpp   |  44 ++++++++++++++++++++++++++++++++------
 test/meshes/cube.cgmesh           | Bin 920 -> 932 bytes
 3 files changed, 41 insertions(+), 11 deletions(-)

diff --git a/src/blu_cat/com/binary_reader.hpp b/src/blu_cat/com/binary_reader.hpp
index fa5d495..a17dc88 100644
--- a/src/blu_cat/com/binary_reader.hpp
+++ b/src/blu_cat/com/binary_reader.hpp
@@ -23,8 +23,8 @@
 
 class BinaryReader
 {
-  I64F _pointer;
-  I64F _size;
+  UI64F _pointer;
+  UI64F _size;
   UI8 *data;
 
 public:
@@ -33,10 +33,10 @@ public:
   BinaryReader(const char *file_path);
   ~BinaryReader();
 
-  inline int
+  inline UI64F
   pointer(){return this->_pointer;};
 
-  inline int
+  inline UI64F
   size(){return this->_size;};
 
   UI8
diff --git a/src/blu_cat/gra/static_mesh.cpp b/src/blu_cat/gra/static_mesh.cpp
index 0d95590..b52d124 100644
--- a/src/blu_cat/gra/static_mesh.cpp
+++ b/src/blu_cat/gra/static_mesh.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright 2022-2024 Frederico de Oliveira Linhares
+ * Copyright 2022-2025 Frederico de Oliveira Linhares
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,6 +24,16 @@
 namespace
 {
 
+struct StaticMeshHeader
+{
+	char file_magic[8];
+	UI32 version;
+	UI32 num_vertexes;
+	UI32 num_indexes;
+};
+
+constexpr UI64F STATIC_MESH_HEADER_SIZE{20};
+
 // Data that is only needed for the command chain but not for the StaticMesh
 // goes here.
 struct MeshBuilder
@@ -51,16 +61,36 @@ load_mesh(void *obj)
 {
   auto self = static_cast<MeshBuilder*>(obj);
 
+  self->mesh->queue_family =
+    BluCat::INT::core.vk_device_with_swapchain->
+		get_queue_family_with_graphics();
+
+	StaticMeshHeader header;
   BinaryReader input{self->mesh_path};
 
-  self->mesh->queue_family =
-    BluCat::INT::core.vk_device_with_swapchain->get_queue_family_with_graphics();
+	{ // Read header
+		input.read_chars(header.file_magic, 8);
+		header.version = input.read_ui32();
+		header.num_vertexes = input.read_ui32();
+		header.num_indexes = input.read_ui32();
+
+		size_t total_file_size{
+			STATIC_MESH_HEADER_SIZE +
+			header.num_vertexes * 8 * 4 +
+			header.num_indexes * 4};
+
+		if(total_file_size != input.size())
+		{
+			std::string error{"File size does not match header information: "};
+			error += self->mesh_path;
+			throw CommandError{error};
+		}
+	}
 
   { // Load vertexes.
-    auto vertex_count{input.read_ui32()};
-    std::vector<BluCat::GRA::StaticMeshVertex> vertexes{vertex_count};
+    std::vector<BluCat::GRA::StaticMeshVertex> vertexes{header.num_vertexes};
 
-    for(auto i{0}; i < vertex_count; i++)
+    for(auto i{0}; i < header.num_vertexes; i++)
     {
       vertexes[i].position = input.read_vec3();
       vertexes[i].normal = input.read_vec3();
@@ -77,7 +107,7 @@ load_mesh(void *obj)
   }
 
   { // Load indexes
-    self->mesh->index_count = input.read_ui32();
+    self->mesh->index_count = header.num_indexes;
     std::vector<uint32_t> indexes(self->mesh->index_count);
 
     for(auto i{0}; i < self->mesh->index_count; i++)
diff --git a/test/meshes/cube.cgmesh b/test/meshes/cube.cgmesh
index a75185c..046a955 100644
Binary files a/test/meshes/cube.cgmesh and b/test/meshes/cube.cgmesh differ
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