feat: add RAII window class with OpenGL 4.1 context

- Add cbt::window class in cbt/ directory with RAII lifecycle
- Add setup_opengl and info_opengl for glad init and GL info
- Add Q key to quit the application
- Update CMakeLists.txt with glfw3 and glad dependencies
- Update AGENTS.md with snake_case naming and shell conventions

AGENTS.md

@@ -44,6 +44,8 @@ to the custom scripts instead of system-installed packages.
 - `auto` for obvious types (e.g. `auto main(...) -> int`)
 - `<>` includes only for system headers (std, OS, etc.)
 - `""` includes for third-party dependencies (e.g. `fmt`, `nlohmann/json`)
+- **Naming:** `snake_case` for variables, functions, and classes
+- **Naming:** `SCREAMING_SNAKE_CASE` only for macros and constants
 - Include order:
   1. C++ standard library headers (`<chrono>`, `<vector>`, etc.)
   2. *(blank line)*
@@ -86,6 +88,9 @@ Example:
 cuber/
   CMakeLists.txt      # Build configuration
   cuber.cpp           # Entry point
+  cbt/                # Project namespace
+    window.hpp        # Window RAII wrapper
+    window.cpp        # Window implementation
   deps/               # Custom Find*.cmake scripts
     Findfmt.cmake     # fmt library
 ```

CMakeLists.txt

@@ -9,8 +9,11 @@ list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/deps")
 
 # Dependencies
 find_package(fmt REQUIRED)
+find_package(glfw3 REQUIRED)
+find_package(glad REQUIRED)
 
 # Target setup
-add_executable(cuber "cuber.cpp")
+add_executable(cuber "cuber.cpp" "cbt/window.cpp")
+target_include_directories(cuber PRIVATE ".")
 target_compile_features(cuber PRIVATE cxx_std_23)
-target_link_libraries(cuber PRIVATE fmt::fmt)
+target_link_libraries(cuber PRIVATE fmt::fmt glfw::glfw glad::glad)

cbt/window.cpp

@@ -0,0 +1,92 @@
+#define GLFW_INCLUDE_NONE
+#include "GLFW/glfw3.h"
+
+#include "window.hpp"
+
+#include <string_view>
+
+#include "glad/glad.h"
+#include "fmt/std.h"
+
+namespace cbt {
+
+auto window::init() -> bool {
+    if (!glfwInit()) {
+        fmt::print("Failed to initialize GLFW\n");
+        return false;
+    }
+    return true;
+}
+
+auto window::terminate() -> void {
+    glfwTerminate();
+}
+
+auto window::setup_opengl() -> bool {
+    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
+        fmt::print("Failed to initialize GLAD\n");
+        return false;
+    }
+    info_opengl();
+    return true;
+}
+
+auto window::info_opengl() -> void {
+    fmt::print("OpenGL Info:\n");
+    fmt::print("  vendor  | {}\n", std::string_view(reinterpret_cast<const char*>(glGetString(GL_VENDOR))));
+    fmt::print("  renderer| {}\n", std::string_view(reinterpret_cast<const char*>(glGetString(GL_RENDERER))));
+    fmt::print("  version | {}\n", std::string_view(reinterpret_cast<const char*>(glGetString(GL_VERSION))));
+    fmt::print("  glsl    | {}\n", std::string_view(reinterpret_cast<const char*>(glGetString(GL_SHADING_LANGUAGE_VERSION))));
+}
+
+window::window(std::string title, int width, int height) {
+    if (!init()) {
+        return;
+    }
+    m_initialized = true;
+
+    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
+    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 1);
+    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
+
+    m_window = glfwCreateWindow(width, height, title.c_str(), nullptr, nullptr);
+    if (!m_window) {
+        fmt::print("Failed to create window\n");
+        terminate();
+        return;
+    }
+
+    glfwMakeContextCurrent(static_cast<GLFWwindow*>(m_window));
+
+    if (!setup_opengl()) {
+        terminate();
+        return;
+    }
+}
+
+window::~window() {
+    if (m_window) {
+        glfwDestroyWindow(static_cast<GLFWwindow*>(m_window));
+    }
+    if (m_initialized) {
+        terminate();
+    }
+}
+
+auto window::should_close() const -> bool {
+    return m_window && glfwWindowShouldClose(static_cast<GLFWwindow*>(m_window));
+}
+
+auto window::valid() const -> bool {
+    return m_window != nullptr;
+}
+
+auto window::swap_buffers() -> void {
+    glfwSwapBuffers(static_cast<GLFWwindow*>(m_window));
+}
+
+auto window::poll_events() -> void {
+    glfwPollEvents();
+}
+
+}

cbt/window.hpp

@@ -0,0 +1,27 @@
+#pragma once
+
+#include <string>
+
+namespace cbt {
+
+class window {
+    void* m_window = nullptr;
+    bool m_initialized = false;
+
+    static auto init() -> bool;
+    static auto terminate() -> void;
+    static auto setup_opengl() -> bool;
+    static auto info_opengl() -> void;
+
+public:
+    explicit window(std::string title, int width, int height);
+    ~window();
+
+    auto should_close() const -> bool;
+    auto valid() const -> bool;
+    auto swap_buffers() -> void;
+    auto poll_events() -> void;
+    auto raw() const -> void* { return m_window; }
+};
+
+}

cuber.cpp

@@ -1,26 +1,27 @@
-#include <chrono>
+#define GLFW_INCLUDE_NONE
-#include <thread>
+#include "GLFW/glfw3.h"
 
-#include "fmt/std.h"
+#include "cbt/window.hpp"
 
-auto main(int argc, char const* argv[]) -> int {
+#include "glad/glad.h"
-    using namespace std::chrono;
-    using namespace std::literals;
 
-    auto start = steady_clock::now();
+auto main(int, char const*[]) -> int {
+    auto w = cbt::window("cuber", 1280, 720);
 
-    while (true) {
+    if (!w.valid()) {
-        auto elapsed = steady_clock::now() - start;
+        return 1;
-        auto totalSec = duration_cast<seconds>(elapsed).count();
+    }
-        auto h = totalSec / 3600;
-        auto m = (totalSec % 3600) / 60;
-        auto s = totalSec % 60;
-        auto ms = duration_cast<milliseconds>(elapsed % 1s).count();
 
-        fmt::print("\033[32m{:02}:{:02}:{:02}\033[0m.\033[90m{:03}\033[0m\r",
+    while (!w.should_close()) {
-                   h, m, s, ms);
+        if (glfwGetKey(static_cast<GLFWwindow*>(w.raw()), GLFW_KEY_Q) == GLFW_PRESS) {
+            break;
+        }
 
-        std::this_thread::sleep_for(10ms);
+        glClearColor(0.6f, 0.8f, 1.0f, 1.0f);
+        glClear(GL_COLOR_BUFFER_BIT);
+
+        w.swap_buffers();
+        w.poll_events();
     }
 
     return 0;

deps/Findglad.cmake

@@ -0,0 +1,68 @@
+# ==============================================================================
+# Find glad
+# ==============================================================================
+# This module fetches the glad OpenGL loader library.
+#
+# Targets provided:
+#   glad::glad - The glad library target
+#
+# Variables set:
+#   glad_FOUND       - TRUE if glad is available
+#   glad_LIBRARIES   - The glad library target (glad::glad)
+#   glad_INCLUDE_DIR - Include directories for glad
+#   glad_VERSION     - Version of glad (commit hash or tag)
+# ==============================================================================
+
+if (DEFINED _FINDGLAD_INCLUDED)
+    return()
+endif()
+set(_FINDGLAD_INCLUDED TRUE)
+
+# Use the version passed to find_package(), or default to commit hash
+if (DEFINED glad_FIND_VERSION AND NOT glad_FIND_VERSION STREQUAL "")
+    set(GLAD_VERSION "${glad_FIND_VERSION}")
+else()
+    set(GLAD_VERSION "f4759d7c5143c0a23391ab05caaf43052cefdd65")
+endif()
+
+message(STATUS "Fetching glad ${GLAD_VERSION}")
+
+include(FetchContent)
+
+find_program(GIT_EXECUTABLE git)
+if (GIT_EXECUTABLE)
+    set(GLAD_FETCH_METHOD "GIT")
+else()
+    message(FATAL_ERROR "Fetch with zip not supported.")
+endif()
+
+if (GLAD_FETCH_METHOD STREQUAL "GIT")
+    FetchContent_Declare(
+        glad
+        GIT_REPOSITORY https://github.com/mononerv/glad.git
+        GIT_TAG        ${GLAD_VERSION}
+    )
+endif()
+
+FetchContent_MakeAvailable(glad)
+
+if (NOT TARGET glad::glad)
+    if (TARGET glad)
+        add_library(glad::glad ALIAS glad)
+    else()
+        message(FATAL_ERROR "Could not fetch glad; no target glad or glad::glad available")
+    endif()
+endif()
+
+set(glad_FOUND        TRUE)
+set(glad_LIBRARIES    glad::glad)
+set(glad_VERSION      "${GLAD_VERSION}")
+get_target_property(_glad_inc glad::glad INTERFACE_INCLUDE_DIRECTORIES)
+set(glad_INCLUDE_DIR  "${_glad_inc}")
+
+# Mark glad includes as SYSTEM to suppress warnings from its headers
+if (_glad_inc AND TARGET glad)
+    set_target_properties(glad PROPERTIES
+        INTERFACE_SYSTEM_INCLUDE_DIRECTORIES "${_glad_inc}"
+    )
+endif()

deps/Findglfw3.cmake

@@ -0,0 +1,81 @@
+# ==============================================================================
+# Find GLFW
+# ==============================================================================
+# This module fetches the GLFW library for window/input handling.
+#
+# Targets provided:
+#   glfw::glfw - The GLFW library target
+#   glfw       - The GLFW library target (non-namespaced)
+#
+# Variables set:
+#   GLFW_FOUND       - TRUE if GLFW is available
+#   GLFW_LIBRARIES   - The GLFW library target (glfw::glfw)
+#   GLFW_INCLUDE_DIR - Include directories for GLFW
+#   GLFW_VERSION     - Version of GLFW (if available)
+# ==============================================================================
+
+if (DEFINED _FINDGLFW_INCLUDED)
+    return()
+endif()
+set(_FINDGLFW_INCLUDED TRUE)
+
+# Use the version passed to find_package(), or default to 3.4
+if (DEFINED GLFW_FIND_VERSION AND NOT GLFW_FIND_VERSION STREQUAL "")
+    set(GLFW_VERSION "${GLFW_FIND_VERSION}")
+else()
+    set(GLFW_VERSION "3.4")
+endif()
+
+message(STATUS "Fetching GLFW ${GLFW_VERSION}")
+
+include(FetchContent)
+
+find_program(GIT_EXECUTABLE git)
+if (GIT_EXECUTABLE)
+    set(GLFW_FETCH_METHOD "GIT")
+else()
+    message(FATAL_ERROR "Fetch with zip not supported.")
+endif()
+
+if (GLFW_FETCH_METHOD STREQUAL "GIT")
+    # Disable GLFW extras to keep builds lightweight.
+    set(GLFW_BUILD_EXAMPLES OFF CACHE BOOL "" FORCE)
+    set(GLFW_BUILD_TESTS    OFF CACHE BOOL "" FORCE)
+    set(GLFW_BUILD_DOCS     OFF CACHE BOOL "" FORCE)
+    set(GLFW_INSTALL        OFF CACHE BOOL "" FORCE)
+    # Environment issue where a cross-compilation script
+    # set(GLFW_BUILD_WAYLAND      OFF CACHE BOOL "" FORCE)
+
+    FetchContent_Declare(
+        glfw
+        GIT_REPOSITORY https://github.com/glfw/glfw.git
+        GIT_TAG        ${GLFW_VERSION}
+    )
+endif()
+
+set(_glfw_suppress_prev ${CMAKE_SUPPRESS_DEVELOPER_WARNINGS})
+set(CMAKE_SUPPRESS_DEVELOPER_WARNINGS TRUE CACHE INTERNAL "")
+FetchContent_MakeAvailable(glfw)
+set(CMAKE_SUPPRESS_DEVELOPER_WARNINGS ${_glfw_suppress_prev} CACHE INTERNAL "")
+
+if (NOT TARGET glfw::glfw)
+    if (TARGET glfw)
+        add_library(glfw::glfw ALIAS glfw)
+    else()
+        message(FATAL_ERROR "Could not fetch GLFW; no target glfw or glfw::glfw available")
+    endif()
+endif()
+
+set(GLFW_FOUND        TRUE)
+set(GLFW_LIBRARIES    glfw::glfw)
+get_target_property(_glfw_inc glfw::glfw INTERFACE_INCLUDE_DIRECTORIES)
+set(GLFW_INCLUDE_DIR  "${_glfw_inc}")
+
+# Mark GLFW includes as SYSTEM to suppress warnings from its headers
+if (_glfw_inc AND TARGET glfw)
+    set_target_properties(glfw PROPERTIES
+        INTERFACE_SYSTEM_INCLUDE_DIRECTORIES "${_glfw_inc}"
+    )
+endif()
+
+set(GLFW_LICENSE_FILE "${glfw_SOURCE_DIR}/LICENSE.md" CACHE FILEPATH "Path to GLFW license file")