From 21fa4c6d6fd2c97234a3ab9a79b77077daf5f205 Mon Sep 17 00:00:00 2001
From: tovjemam <zbyvaj@seznam.cz>
Date: Wed, 6 Aug 2025 20:21:16 +0200
Subject: [PATCH] Mesh loading

---
 CMakeLists.txt           |  7 ++--
 src/assets/load_mesh.cpp |  0
 src/assets/load_mesh.hpp | 15 ---------
 src/assets/mesh.cpp      | 73 ++++++++++++++++++++++++++++++++++++++++
 src/assets/mesh.hpp      | 44 ++++++++++++++++++++++++
 5 files changed, 120 insertions(+), 19 deletions(-)
 delete mode 100644 src/assets/load_mesh.cpp
 delete mode 100644 src/assets/load_mesh.hpp
 create mode 100644 src/assets/mesh.cpp
 create mode 100644 src/assets/mesh.hpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4a15727..ab61e14 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,8 +1,8 @@
 cmake_minimum_required(VERSION 3.15)
 project(PortalGame)
 
-# Enable C++17
-set(CMAKE_CXX_STANDARD 17)
+# Enable C++20
+set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 # Add src directory
@@ -12,8 +12,7 @@ add_executable(PortalGame
     "src/app.cpp"
     "src/gl.hpp"
     "src/utils.hpp"
-    "src/assets/load_mesh.hpp"
-    "src/assets/load_mesh.cpp"
+    "src/assets/mesh.cpp"
     "src/gfx/buffer_object.cpp"
     "src/gfx/buffer_object.hpp"
     "src/gfx/texture.cpp"
diff --git a/src/assets/load_mesh.cpp b/src/assets/load_mesh.cpp
deleted file mode 100644
index e69de29..0000000
diff --git a/src/assets/load_mesh.hpp b/src/assets/load_mesh.hpp
deleted file mode 100644
index a258cab..0000000
--- a/src/assets/load_mesh.hpp
+++ /dev/null
@@ -1,15 +0,0 @@
-#pragma once
-
-#include <memory>
-#include <string>
-
-#include "gfx/vertex_array.hpp"
-
-namespace assets
-{
-
-std::shared_ptr<VertexArray> LoadMesh(const std::string& filename);
-
-}
-
-
diff --git a/src/assets/mesh.cpp b/src/assets/mesh.cpp
new file mode 100644
index 0000000..fb0f104
--- /dev/null
+++ b/src/assets/mesh.cpp
@@ -0,0 +1,73 @@
+#include "mesh.hpp"
+#include <fstream>
+#include <sstream>
+#include <stdexcept>
+#include <vector>
+#include <map>
+
+std::shared_ptr<assets::Mesh> assets::Mesh::LoadFromFile(const std::string& filename)
+{
+    std::ifstream file(filename, std::ios::binary);
+
+    if (!file.is_open())
+    {
+        throw std::runtime_error("Failed to open mesh file: " + filename);
+    }
+
+    std::vector<MeshVertex> verts;
+    std::vector<MeshTriangle> tris;
+	std::vector<MeshMaterialSlot> materials;
+
+    std::string line;
+
+    while (std::getline(file, line))
+    {
+        if (line.empty() || line[0] == '#') // Skip empty lines and comments
+            continue;
+
+        std::istringstream iss(line);
+
+        std::string command;
+        iss >> command;
+
+        if (command == "v") // Vertex
+        {
+            MeshVertex& vertex = verts.emplace_back();
+            iss >> vertex.pos.x >> vertex.pos.y >> vertex.pos.z;
+            iss >> vertex.normal.x >> vertex.normal.y >> vertex.normal.z;
+            iss >> vertex.uv.x >> vertex.uv.y;
+            iss >> vertex.lightmap_uv.x >> vertex.lightmap_uv.y;
+        }
+        else if (command == "m") // Material switch
+        {
+            if (materials.size() > 0)
+            {
+				MeshMaterialSlot& last_material = materials.back();
+				last_material.num_tris = tris.size() - last_material.first_tri;
+            }
+
+			MeshMaterialSlot& material = materials.emplace_back();
+            iss >> material.name;
+			material.first_tri = tris.size();
+
+        }
+        else if (command == "f") // Face
+        {
+			MeshTriangle& tri = tris.emplace_back();
+			iss >> tri.vert[0] >> tri.vert[1] >> tri.vert[2];
+        }
+    }
+
+    if (materials.size() > 0)
+    {
+        MeshMaterialSlot& last_material = materials.back();
+        last_material.num_tris = tris.size() - last_material.first_tri;
+	}
+
+    file.close();
+    if (verts.empty() || tris.empty())
+    {
+        throw std::runtime_error("Mesh file is empty or malformed: " + filename);
+    }
+	return std::make_shared<Mesh>(verts, tris, materials);
+}
diff --git a/src/assets/mesh.hpp b/src/assets/mesh.hpp
new file mode 100644
index 0000000..2e0c4de
--- /dev/null
+++ b/src/assets/mesh.hpp
@@ -0,0 +1,44 @@
+#pragma once
+
+#include <memory>
+#include <string>
+#include <span>
+#include <glm/glm.hpp>
+
+#include "gfx/vertex_array.hpp"
+#include "gfx/texture.hpp"
+
+namespace assets
+{
+	struct MeshVertex
+	{
+		glm::vec3 pos;
+		glm::vec3 normal;
+		glm::vec2 uv;
+		glm::vec2 lightmap_uv;
+	};
+
+	struct MeshTriangle
+	{
+		uint32_t vert[3];
+	};
+
+	struct MeshMaterialSlot
+	{
+		std::string name;
+		std::shared_ptr<gfx::Texture> texture;
+		size_t first_tri = 0;
+		size_t num_tris = 0;
+	};
+
+	class Mesh
+	{
+		gfx::VertexArray va_;
+		std::vector<MeshMaterialSlot> materials_;
+
+	public:
+		Mesh(std::span<MeshVertex> verts, std::span<MeshTriangle> tris, std::span<MeshMaterialSlot> materials);
+
+		static std::shared_ptr<Mesh> LoadFromFile(const std::string& filename);
+	};
+}