From 9bcb8385fe4f5374ef7c0a7a58c812ba56a00e1f Mon Sep 17 00:00:00 2001
From: Preston McGee <pmcgeee03@gmail.com>
Date: Sat, 16 May 2026 13:37:44 -0700
Subject: [PATCH] add device clas which enumerates availble gpu devices

---
 CMakeLists.txt |  1 +
 README.md      |  8 ++++++++
 src/Device.cpp | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++
 src/Device.hpp | 24 ++++++++++++++++++++++
 src/Engine.cpp |  7 ++++++-
 5 files changed, 95 insertions(+), 1 deletion(-)
 create mode 100644 src/Device.cpp
 create mode 100644 src/Device.hpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9e7c3d1..8dae3ac 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -33,6 +33,7 @@ add_library(maiden_core STATIC
     src/App.cpp
     src/Window.cpp
     src/Engine.cpp
+    src/Device.cpp
     # include extra source files here
 )
 
diff --git a/README.md b/README.md
index 98f0210..75fa95b 100644
--- a/README.md
+++ b/README.md
@@ -83,10 +83,18 @@ This seems like a WSL specific error and causes real issues with relaying graphi
 $ sudo add-apt-repository ppa:kisak/kisak-mesa
 $ sudo apt-get update && sudo apt upgrade
 ```
+
 Note: this resulted in the following erre "WARNING: dzn is not a conformant Vulkan implementation, testing use only." Running `$ vkcube` showed that this indeed was just a warning.
 
 (for those curious, dzn is a compaitibility layer between DirectX12 and Vulkan for that WSL conformity)
 
+### Could not locate a Nvidia GPU
+```bash
+$ sudo add-apt-repository ppa:kisak/turtle
+$ sudo apt update
+$ sudo apt upgrade
+```
+verify with `$ vulkaninfo --summary` to ensure your GPU is shown.
 
 ## Development Roadmap
 ### lots of todo here
diff --git a/src/Device.cpp b/src/Device.cpp
new file mode 100644
index 0000000..92caf16
--- /dev/null
+++ b/src/Device.cpp
@@ -0,0 +1,56 @@
+
+#include "Device.hpp"
+
+#include <iostream>
+
+Device::Device(vk::raii::Instance* instance): instance_(instance) {
+
+}
+
+Device::~Device() {
+
+}
+
+bool Device::selectPhysicalDevice() {
+
+    std::vector<vk::raii::PhysicalDevice> physicalDevices = instance_->enumeratePhysicalDevices();
+
+    if(physicalDevices.empty()) {
+        std::cout << "[" << __FUNCTION__ << ": " << __LINE__ << "] Error: no physical devices with Vulkan support found." << std::endl;
+        return false;
+    }
+
+    // validate found devices
+    uint32_t maxScore = 0;
+    for(vk::raii::PhysicalDevice& physicalDevice : physicalDevices) {
+        uint32_t capabilityScore = evaluatePhysicalDevice(physicalDevice);
+        if(capabilityScore > maxScore) {
+            maxScore = capabilityScore;
+            physicalDevice_ = physicalDevice;
+        }
+    }
+    if(maxScore = 0) {
+        std::cout << "[" << __FUNCTION__ << ": " << __LINE__ << "] Error: physical devices found, but none capable for this engine." << std::endl;
+        return false;
+    } else {
+        vk::PhysicalDeviceProperties deviceProperties = physicalDevice_.getProperties();
+        std::cout << "[" << __FUNCTION__ << ": " << __LINE__ << "] Physical device selected: " << deviceProperties.deviceName << std::endl;
+        return true;
+    }
+
+}
+
+uint32_t Device::evaluatePhysicalDevice(vk::raii::PhysicalDevice& device) {
+
+    vk::PhysicalDeviceProperties deviceProperties = device.getProperties();
+    vk::PhysicalDeviceFeatures deviceFeatures = device.getFeatures();
+
+    std::cout << "[" << __FUNCTION__ << ": " << __LINE__ << "] Physical device found: " << deviceProperties.deviceName << std::endl;
+
+    if(deviceProperties.deviceType == vk::PhysicalDeviceType::eDiscreteGpu) {
+        return 2;
+    } else {
+        return 1;
+    } // i.e. a descrete gpu is preferable to an integrated gpu
+
+}
diff --git a/src/Device.hpp b/src/Device.hpp
new file mode 100644
index 0000000..a70bfd2
--- /dev/null
+++ b/src/Device.hpp
@@ -0,0 +1,24 @@
+
+#pragma once
+
+#include <vulkan/vulkan_raii.hpp>
+
+class Device {
+
+    public:
+
+    Device(vk::raii::Instance* instance);
+    ~Device();
+
+    // assigns a capable gpu vkdevice to physicalDevice 
+    bool selectPhysicalDevice();
+
+    private:
+
+    // gives a device a score to attempt to select the most capable device
+    uint32_t evaluatePhysicalDevice(vk::raii::PhysicalDevice& device);
+
+    vk::raii::Instance* instance_ = nullptr;
+    vk::raii::PhysicalDevice physicalDevice_ = nullptr;
+    
+};
diff --git a/src/Engine.cpp b/src/Engine.cpp
index 35afc4f..2bcbebe 100644
--- a/src/Engine.cpp
+++ b/src/Engine.cpp
@@ -3,6 +3,8 @@
 
 #include <iostream>
 
+#include "Device.hpp"
+
 Engine::Engine(Window* window): window_(window) {
 
     // cleans up this constructor 
@@ -19,8 +21,11 @@ void Engine::init() {
         std::cout << "[" << __FUNCTION__ << ": " << __LINE__ << "] Error creating Vulkan instance." << std::endl;
     }
 
-    // next steps:
     // device selection and setup
+    Device device(&instance_);
+    device.selectPhysicalDevice();
+    
+    // next steps:
     // queue creation
     // vulkan memory allocator
     // create vulkan surface