Selecting a physical device

Hello_triangle/main.cpp

@@ -4,9 +4,6 @@
 
 */
 
-
-
-
 #define GLFW_INCLUDE_VULKAN
 #include <GLFW/glfw3.h>
 #include <iostream>
@@ -14,6 +11,7 @@
 #include <cstdlib>
 #include <vector>
 #include <cstring>
+#include <optional>
 
 
 const uint32_t WIDTH = 800;
@@ -46,6 +44,7 @@ class HelloTriangleApplication{
         GLFWwindow* window;
         VkInstance instance;
         VkDebugUtilsMessengerEXT debugMessenger;
+        VkPhysicalDevice physicalDevice = VK_NULL_HANDLE;
 
         void initWindow(){
             glfwInit();
@@ -59,8 +58,82 @@ class HelloTriangleApplication{
         void initVulkan(){
             createInstance();
             setupDebugMessenger();
+            pickPhysicalDevice();
         }
 
+        void pickPhysicalDevice(){
+            uint32_t deviceCount = 0;
+            vkEnumeratePhysicalDevices(instance, &deviceCount, nullptr);
+            
+            if(deviceCount == 0 ){
+                throw std::runtime_error("failed to find GPU's with Vulkan support!");
+            }
+            
+            std::vector<VkPhysicalDevice> devices(deviceCount);
+            vkEnumeratePhysicalDevices(instance, &deviceCount, devices.data());
+
+            for(const auto& device : devices){
+                if(isDeviceSuitable(device)){
+                    physicalDevice = device;
+                    break;
+                }
+            }
+
+            if(physicalDevice == VK_NULL_HANDLE){
+                throw std::runtime_error("failed to find a suitable GPU");
+            }
+        }
+
+        bool isDeviceSuitable(VkPhysicalDevice device){
+            VkPhysicalDeviceProperties deviceProperties;
+            vkGetPhysicalDeviceProperties(device, &deviceProperties);
+
+            VkPhysicalDeviceFeatures deviceFeatures;
+            vkGetPhysicalDeviceFeatures(device, &deviceFeatures);
+
+
+            QueueFamilyIndices indices = findQueueFamilies(device);
+
+            return indices.isComplete();
+        }
+
+        struct QueueFamilyIndices {
+            std::optional<uint32_t> graphicsFamily;
+
+            bool isComplete(){
+                return graphicsFamily.has_value();
+            }
+
+        };
+
+        QueueFamilyIndices findQueueFamilies (VkPhysicalDevice device ){
+            QueueFamilyIndices indices;
+
+            uint32_t queueFamilyCount = 0;
+            vkGetPhysicalDeviceQueueFamilyProperties(device, &queueFamilyCount, nullptr);
+
+            std::vector<VkQueueFamilyProperties> queueFamilies(queueFamilyCount);
+            vkGetPhysicalDeviceQueueFamilyProperties(device, &queueFamilyCount, queueFamilies.data());
+
+            int i = 0;
+            for (const auto& queueFamily : queueFamilies){
+                if(queueFamily.queueFlags & VK_QUEUE_GRAPHICS_BIT){
+                    indices.graphicsFamily = i;
+                }
+
+                if(indices.isComplete()){
+                    break;
+                }
+
+                i++;
+            }
+
+            return indices;
+        }
+
+
+
+
         VkResult CreateDebugUtilsMessengerEXT(VkInstance instance, const VkDebugUtilsMessengerCreateInfoEXT* pCreateInfo, const VkAllocationCallbacks* pAllocator, VkDebugUtilsMessengerEXT* pDebugMessenger) {
             auto func = (PFN_vkCreateDebugUtilsMessengerEXT) vkGetInstanceProcAddr(instance, "vkCreateDebugUtilsMessengerEXT");
             if (func != nullptr) {