main.cpp

#define GLFW_INCLUDE_VULKAN
#include <GLFW/glfw3.h>
#include <iostream>
#include <stdexcept>
#include <cstdlib>
#include <vector>
#include <cstring>
#include <map>
#include <optional>

const uint32_t WIDTH = 800;
const uint32_t HEIGHT = 600;

const std::vector<const char*> validationLayers = {
	"VK_LAYER_KHRONOS_validation",
	"VK_LAYER_LUNARG_monitor"
};

#ifdef NDEBUG
const bool enableValidationLayers = false;
#else
const bool enableValidationLayers = true;
#endif

class HelloTriangleApplication {
public:
	void run() {
		initWindow();
		initVulkan();
		mainLoop();
		cleanup();
	}

private:
	struct QueueFamilyIndices {
		std::optional<uint32_t> graphicsFamily;

		bool isComplete() {
			return graphicsFamily.has_value();
		}
	};

	GLFWwindow* window;
	VkInstance instance;
	void initWindow() {
		glfwInit();
		glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
		glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);
		window = glfwCreateWindow(WIDTH, HEIGHT, "Vulkan", nullptr, nullptr);
	}
	void initVulkan() {
		createInstance();
		pickPhysicalDevice();
	}

	void mainLoop() {
		while (!glfwWindowShouldClose(window)) {
			glfwPollEvents();
		}
	}

	void cleanup() {
		vkDestroyInstance(instance, nullptr);
		glfwDestroyWindow(window);
		glfwTerminate();
	}

	void createInstance()
	{
		if (enableValidationLayers && !checkValidationLayerSupport()) {
			throw std::runtime_error("validation layers requested, but not available!");
		}

		VkApplicationInfo appInfo{};
		appInfo.sType = VK_STRUCTURE_TYPE_APPLICATION_INFO;
		appInfo.pApplicationName = "Hello Triangle";
		appInfo.applicationVersion = VK_MAKE_VERSION(1, 0, 0);
		appInfo.pEngineName = "No Engine";
		appInfo.engineVersion = VK_MAKE_VERSION(1, 0, 0);
		appInfo.apiVersion = VK_API_VERSION_1_0;

		VkInstanceCreateInfo createInfo{};
		createInfo.sType = VK_STRUCTURE_TYPE_INSTANCE_CREATE_INFO;
		createInfo.pApplicationInfo = &appInfo;
		uint32_t glfwExtensionCount = 0;
		const char** glfwExtensions;
		glfwExtensions = glfwGetRequiredInstanceExtensions(&glfwExtensionCount);
		createInfo.enabledExtensionCount = glfwExtensionCount;
		createInfo.ppEnabledExtensionNames = glfwExtensions;

		if (enableValidationLayers) {
			createInfo.enabledLayerCount = static_cast<uint32_t>(validationLayers.size());
			createInfo.ppEnabledLayerNames = validationLayers.data();
		}
		else {
			createInfo.enabledLayerCount = 0;
		}

		//const VkAllocationCallbacks* pAllocator;
		//pAllocator.pUserData = 

		if (vkCreateInstance(&createInfo, nullptr, &instance) != VK_SUCCESS) {
			throw std::runtime_error("failed to create instance!");
		}

		uint32_t extensionCount = 0;
		vkEnumerateInstanceExtensionProperties(nullptr, &extensionCount, nullptr);

		std::vector<VkExtensionProperties> extensions(extensionCount);

		vkEnumerateInstanceExtensionProperties(nullptr, &extensionCount, extensions.data());

		std::cout << "available extensions:\n";

		for (const auto& extension : extensions) {
			std::cout << '\t' << extension.extensionName << '\n';
		}
	}

	bool checkValidationLayerSupport() {
		uint32_t layerCount;
		vkEnumerateInstanceLayerProperties(&layerCount, nullptr);

		std::vector<VkLayerProperties> availableLayers(layerCount);
		vkEnumerateInstanceLayerProperties(&layerCount, availableLayers.data());

		for (const char* layerName : validationLayers) {
			bool layerFound = false;

			for (const auto& layerProperties : availableLayers) {
				if (strcmp(layerName, layerProperties.layerName) == 0) {
					layerFound = true;
					break;
				}
			}

			if (!layerFound) {
				return false;
			}
		}

		return true;
	}

	void pickPhysicalDevice()
	{
		VkPhysicalDevice physicalDevice = VK_NULL_HANDLE;

		uint32_t deviceCount = 0;
		vkEnumeratePhysicalDevices(instance, &deviceCount, nullptr);

		if (deviceCount == 0) {
			throw std::runtime_error("failed to find GPUs with Vulkan support!");
		}

		std::vector<VkPhysicalDevice> devices(deviceCount);
		vkEnumeratePhysicalDevices(instance, &deviceCount, devices.data());
		// Use an ordered map to automatically sort candidates by increasing score
		
		std::multimap<int, VkPhysicalDevice> candidates;

		for (const auto& device : devices) {
			int score = rateDeviceSuitability(device);
			candidates.insert(std::make_pair(score, device));
		}

		// Check if the best candidate is suitable at all
		if (candidates.rbegin()->first > 0) {
			if (isDeviceSuitable(candidates.rbegin()->second))
			{
				physicalDevice = candidates.rbegin()->second;
			}
			else {
				throw std::runtime_error("failed to find a suitable GPU!");
			}
		}
		else {
			throw std::runtime_error("failed to find a suitable GPU!");
		}


	}

	int rateDeviceSuitability(VkPhysicalDevice device)
	{
		VkPhysicalDeviceProperties deviceProperties;
		VkPhysicalDeviceFeatures deviceFeatures;
		vkGetPhysicalDeviceProperties(device, &deviceProperties);
		vkGetPhysicalDeviceFeatures(device, &deviceFeatures);

		int score = 0;

		// Discrete GPUs have a significant performance advantage
		if (deviceProperties.deviceType == VK_PHYSICAL_DEVICE_TYPE_DISCRETE_GPU) {
			score += 1000;
		}

		// Maximum possible size of textures affects graphics quality
		score += deviceProperties.limits.maxImageDimension2D;

		// Application can't function without geometry shaders
		if (!deviceFeatures.geometryShader) {
			return 0;
		}

		return score;
	}

	bool isDeviceSuitable(VkPhysicalDevice device) {
		QueueFamilyIndices indices = findQueueFamilies(device);

		return indices.isComplete();
	}


	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;
	}
};

int main() {
	HelloTriangleApplication app;

	try {
		app.run();
	}
	catch (const std::exception& e) {
		std::cerr << e.what() << std::endl;
		return EXIT_FAILURE;
	}

	return EXIT_SUCCESS;
}