HelloTriangleApplication.cpp

#define GLFW_INCLUDE_VULKAN
#include <GLFW/glfw3.h>
//#include <vulkan/vulkan.h>
#include <iostream>
#include <stdexcept>
#include <functional>	// lambda functions 
#include <cstdlib>		// EXIT_FAILURE / SUCCESS
#include <optional>		// used in QueueFamilyIndices struct
#include <set>
#include <cstdint>		// Necessary for UINT32_MAX
#include <algorithm>	// std::clamp
#include <fstream>		// to load in shader files
#include <glm/glm.hpp>	// linear algrebra stuff
#include <array>
#define GLM_FORCE_RADIANS
#define GLM_FORCE_DEPTH_ZERO_TO_ONE
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <chrono>
#define STB_IMAGE_IMPLEMENTATION
#include <stb_image.h>
#define TINYOBJLOADER_IMPLEMENTATION
#include <tiny_obj_loader.h>

#include "Vertex.h"
#include "RenderObject.h"

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

//const std::string MODEL_PATH = "models/water.obj";
//const std::string TEXTURE_PATH = "textures/water_texture.png";

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

const std::vector<const char*> deviceExtensions = { 
	VK_KHR_SWAPCHAIN_EXTENSION_NAME 
};

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

//struct Vertex {
//	glm::vec3 pos;
//	glm::vec3 color;
//	glm::vec2 texCoord;
//
//	static VkVertexInputBindingDescription getBindingDescription() {
//		VkVertexInputBindingDescription bindingDescription{};
//		bindingDescription.binding = 0;			// start index
//		bindingDescription.stride = sizeof(Vertex);
//		bindingDescription.inputRate = VK_VERTEX_INPUT_RATE_VERTEX;		// move per vertex (or per instance)
//		return bindingDescription;
//	}
//
//	static std::array<VkVertexInputAttributeDescription, 3> getAttributeDescriptions() {
//		std::array<VkVertexInputAttributeDescription, 3> attributeDescriptions{};
//
//		attributeDescriptions[0].binding = 0;
//		attributeDescriptions[0].location = 0;
//		attributeDescriptions[0].format = VK_FORMAT_R32G32B32_SFLOAT;
//		attributeDescriptions[0].offset = offsetof(Vertex, pos);
//
//		attributeDescriptions[1].binding = 0;
//		attributeDescriptions[1].location = 1;
//		attributeDescriptions[1].format = VK_FORMAT_R32G32B32_SFLOAT;
//		attributeDescriptions[1].offset = offsetof(Vertex, color);
//
//		attributeDescriptions[2].binding = 0;
//		attributeDescriptions[2].location = 2;
//		attributeDescriptions[2].format = VK_FORMAT_R32G32_SFLOAT;
//		attributeDescriptions[2].offset = offsetof(Vertex, texCoord);
//
//		return attributeDescriptions;
//	}
//};

struct UniformBufferObject {
	glm::mat4 model;
	glm::mat4 view;
	glm::mat4 proj;
};


class HelloTriangleApplication {
public:
	void run() {
		std::cout << "started program\n";
		initWindow();
		initVulkan();
		mainLoop();
		cleanup();
		std::cout << "closed program\n";
	}

private:
	GLFWwindow* window;
	VkInstance instance;
	
	VkPhysicalDevice physicalDevice = VK_NULL_HANDLE;		// physical gpu, implicitly cleaned
	VkDevice device;			// logical gpu to interface to physical
	
	VkQueue graphicsQueue;		// graphics pipeline command queue / implicitly cleaned
	VkSurfaceKHR surface;		// abstract surface to display rendered images
	VkQueue presentQueue;
	VkSwapchainKHR swapChain;
	std::vector<VkImage> swapChainImages;	// handles of swap chain images for rendering / implicitly cleaned
	VkFormat swapChainImageFormat;	// color format (32bit rgba)
	VkExtent2D swapChainExtent;		// swap chain image resolution
	std::vector<VkImageView> swapChainImageViews;
	VkRenderPass renderPass;
	VkDescriptorSetLayout descriptorSetLayout;
	VkPipelineLayout pipelineLayout;
	VkPipeline graphicsPipeline;
	std::vector<VkFramebuffer> swapChainFramebuffers;

	VkCommandPool commandPool;
	std::vector<VkCommandBuffer> commandBuffers;	// command buffer for rendering / one for every Framebuffer

	const int MAX_FRAMES_IN_FLIGHT = 2;			// frames to process concurrently
	size_t currentFrame = 0;
	std::vector<VkSemaphore> imageAvailableSemaphores;
	std::vector<VkSemaphore> renderFinishedSemaphores;
	std::vector<VkFence> inFlightFences;		// to sync cpu / gpu
	std::vector<VkFence> imagesInFlight;		// keep images in order

	std::vector<RenderObject> renderObjects;

	VkImage depthImage;
	VkDeviceMemory depthImageMemory;
	VkImageView depthImageView;

	float zoomLevel = 3.0f;
	int whichMolecule = 0;

	bool framebufferResized = false;		// flag if window resized (will recreate swapchain)
	bool keysHeld[1024];

	std::chrono::steady_clock::time_point prevTime;
	std::chrono::steady_clock::time_point currTime;


	// initialize desktop window (glfw)
	void initWindow() {
		glfwInit();		//initialize glfw library

		glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);	//dont create opengl context
		//glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);		//disable window resize
		
		window = glfwCreateWindow(WIDTH, HEIGHT, "Vulkan", nullptr, nullptr);
		glfwSetWindowUserPointer(window, this);
		glfwSetFramebufferSizeCallback(window, framebufferResizeCallback);
		glfwSetKeyCallback(window, key_callback);
	}

	static void framebufferResizeCallback(GLFWwindow* window, int width, int height) {
		auto app = reinterpret_cast<HelloTriangleApplication*>(glfwGetWindowUserPointer(window));
		app->framebufferResized = true;
	}

	static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
	{
		auto app = reinterpret_cast<HelloTriangleApplication*>(glfwGetWindowUserPointer(window));
		if (key >= 0 && key < 1024)
		{
			if (action == GLFW_PRESS)
			{
				app->keysHeld[key] = true;
			}
			else if (action == GLFW_RELEASE)
				app->keysHeld[key] = false;
		}
	}

	// initialize vulkan library 
	void initVulkan() {
		createInstance();
		createSurface();
		pickPhysicalDevice();
		createLogicalDevice();
		createSwapChain();
		createImageViews();
		createRenderPass();
		createDescriptorSetLayout();
		createGraphicsPipeline();
		createCommandPool();
		createDepthResources();
		createFramebuffers();
		createResources();
		createCommandBuffers();
		createSyncObjects();
	}

	void createResources() {
		RenderObject water_molecule = createRenderObject("models/water.obj", "textures/water_texture.png");
		water_molecule.shouldRender = true;
		renderObjects.push_back(water_molecule);

		RenderObject water_desc = createRenderObject("models/quad.obj", "textures/water_desc.png");
		water_desc.modelMatrix = glm::scale(water_desc.modelMatrix, glm::vec3(0.25f));
		water_desc.modelMatrix = glm::translate(water_desc.modelMatrix, glm::vec3(0.0, -3.0, 0.0));
		water_desc.shouldRender = true;
		renderObjects.push_back(water_desc);

		RenderObject propane_molecule = createRenderObject("models/propane.obj", "textures/propane_texture.png");
		renderObjects.push_back(propane_molecule);

		RenderObject propane_desc = createRenderObject("models/quad.obj", "textures/propane_desc.png");
		propane_desc.modelMatrix = glm::scale(propane_desc.modelMatrix, glm::vec3(0.25f));
		propane_desc.modelMatrix = glm::translate(propane_desc.modelMatrix, glm::vec3(0.0, -3.0, 0.0));
		renderObjects.push_back(propane_desc);

		RenderObject bernstein_molecule = createRenderObject("models/bernstein.obj", "textures/bernstein_texture.png");
		renderObjects.push_back(bernstein_molecule);

		RenderObject bernstein_desc = createRenderObject("models/quad.obj", "textures/bernstein_desc.png");
		bernstein_desc.modelMatrix = glm::scale(bernstein_desc.modelMatrix, glm::vec3(0.25f));
		bernstein_desc.modelMatrix = glm::translate(bernstein_desc.modelMatrix, glm::vec3(0.0, -3.0, 0.0));
		renderObjects.push_back(bernstein_desc);

		std::cout << "created " << renderObjects.size() << " render objects\n";
	}

	RenderObject createRenderObject(std::string modelPath, std::string texturePath) {
		RenderObject renderObject;
		createTextureImage(renderObject.textureImage, renderObject.textureImageMemory, texturePath);
		createTextureImageView(renderObject.textureImageView, renderObject.textureImage);
		createTextureSampler(renderObject.textureSampler);
		loadModel(renderObject.vertices, renderObject.indices, modelPath);
		createVertexBuffer(renderObject.vertexBuffer, renderObject.vertexBufferMemory, renderObject.vertices);
		createIndexBuffer(renderObject.indexBuffer, renderObject.indexBufferMemory, renderObject.indices);
		createUniformBuffers(renderObject.uniformBuffers, renderObject.uniformBuffersMemory);
		createDescriptorPool(renderObject.descriptorPool);
		createDescriptorSets(renderObject.descriptorSets, renderObject.descriptorPool, renderObject.uniformBuffers, renderObject.textureImageView, renderObject.textureSampler);
		renderObject.modelMatrix = glm::mat4(1.0f);
		return renderObject;
	}

	void mainLoop() {
		while (!glfwWindowShouldClose(window)) {
			glfwPollEvents();
			gameLogic();
			drawFrame();
		}
		vkDeviceWaitIdle(device);
	}

	void gameLogic() {
		prevTime = currTime;
		currTime = std::chrono::high_resolution_clock::now();
		float time = std::chrono::duration<float, std::chrono::seconds::period>(currTime - prevTime).count();

		if (keysHeld[GLFW_KEY_D])
			renderObjects[whichMolecule].modelMatrix = glm::rotate(renderObjects[whichMolecule].modelMatrix, time * glm::radians(45.0f), glm::vec3(0.0f, 1.0f, 0.0f));
		if (keysHeld[GLFW_KEY_A])
			renderObjects[whichMolecule].modelMatrix = glm::rotate(renderObjects[whichMolecule].modelMatrix, time * glm::radians(-45.0f), glm::vec3(0.0f, 1.0f, 0.0f));
		if (keysHeld[GLFW_KEY_W])
			renderObjects[whichMolecule].modelMatrix = glm::rotate(renderObjects[whichMolecule].modelMatrix, time * glm::radians(-45.0f), glm::vec3(1.0f, 0.0f, 0.0f));
		if (keysHeld[GLFW_KEY_S])
			renderObjects[whichMolecule].modelMatrix = glm::rotate(renderObjects[whichMolecule].modelMatrix, time * glm::radians(45.0f), glm::vec3(1.0f, 0.0f, 0.0f));
		if (keysHeld[GLFW_KEY_Q])
			renderObjects[whichMolecule].modelMatrix = glm::rotate(renderObjects[whichMolecule].modelMatrix, time * glm::radians(45.0f), glm::vec3(0.0f, 0.0f, 1.0f));
		if (keysHeld[GLFW_KEY_E])
			renderObjects[whichMolecule].modelMatrix = glm::rotate(renderObjects[whichMolecule].modelMatrix, time * glm::radians(-45.0f), glm::vec3(0.0f, 0.0f, 1.0f));
		if (keysHeld[GLFW_KEY_Z])
			zoomLevel += 0.1;
		if (keysHeld[GLFW_KEY_X])
			zoomLevel -= 0.1;

		if (keysHeld[GLFW_KEY_1]) {
			renderObjects[0].shouldRender = true;
			renderObjects[1].shouldRender = true;
			renderObjects[2].shouldRender = false;
			renderObjects[3].shouldRender = false;
			renderObjects[4].shouldRender = false;
			renderObjects[5].shouldRender = false;
			whichMolecule = 0;
		}
		else if (keysHeld[GLFW_KEY_2]) {
			renderObjects[0].shouldRender = false;
			renderObjects[1].shouldRender = false;
			renderObjects[2].shouldRender = true;
			renderObjects[3].shouldRender = true;
			renderObjects[4].shouldRender = false;
			renderObjects[5].shouldRender = false;
			whichMolecule = 2;
		}
		else if (keysHeld[GLFW_KEY_3]) {
			renderObjects[0].shouldRender = false;
			renderObjects[1].shouldRender = false;
			renderObjects[2].shouldRender = false;
			renderObjects[3].shouldRender = false;
			renderObjects[4].shouldRender = true;
			renderObjects[5].shouldRender = true;
			whichMolecule = 4;
		}
	}

	void drawFrame() {
		// wait for frame to be finished
		vkWaitForFences(device, 1, &inFlightFences[currentFrame], VK_TRUE, UINT64_MAX);

		uint32_t imageIndex;
		VkResult result = vkAcquireNextImageKHR(device, swapChain, UINT64_MAX, imageAvailableSemaphores[currentFrame], VK_NULL_HANDLE, &imageIndex);

		// check if swapchain needs to be recreated
		if (result == VK_ERROR_OUT_OF_DATE_KHR) {
			recreateSwapChain();
			return;
		}
		else if (result != VK_SUCCESS && result != VK_SUBOPTIMAL_KHR)
			throw std::runtime_error("failed to acquire swapchain image!");

		if (imagesInFlight[imageIndex] != VK_NULL_HANDLE)	// check if previous frame is using this image (if there is fence to wait on)
			vkWaitForFences(device, 1, &imagesInFlight[imageIndex], VK_TRUE, UINT64_MAX);
		imagesInFlight[imageIndex] = inFlightFences[currentFrame];		// mark image as now being in use by this frame

		updateUniformBuffer(imageIndex, renderObjects[0]);
		updateUniformBufferUI(imageIndex, renderObjects[1]);
		updateUniformBuffer(imageIndex, renderObjects[2]);
		updateUniformBufferUI(imageIndex, renderObjects[3]);
		updateUniformBuffer(imageIndex, renderObjects[4]);
		updateUniformBufferUI(imageIndex, renderObjects[5]);
		
		VkSubmitInfo submitInfo{};
		submitInfo.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;
		VkSemaphore waitSemaphores[] = { imageAvailableSemaphores[currentFrame] };
		VkPipelineStageFlags waitStages[] = { VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT };
		submitInfo.waitSemaphoreCount = 1;
		submitInfo.pWaitSemaphores = waitSemaphores;
		submitInfo.pWaitDstStageMask = waitStages;
		submitInfo.commandBufferCount = 1;
		submitInfo.pCommandBuffers = &commandBuffers[imageIndex];
		VkSemaphore signalSemaphores[] = { renderFinishedSemaphores[currentFrame] };
		submitInfo.signalSemaphoreCount = 1;
		submitInfo.pSignalSemaphores = signalSemaphores;

		vkResetFences(device, 1, &inFlightFences[currentFrame]);

		if (vkQueueSubmit(graphicsQueue, 1, &submitInfo, inFlightFences[currentFrame]) != VK_SUCCESS)
			throw std::runtime_error("failed to submit draw command buffer!");

		// submit result back to swap chain
		VkPresentInfoKHR presentInfo{};
		presentInfo.sType = VK_STRUCTURE_TYPE_PRESENT_INFO_KHR;
		presentInfo.waitSemaphoreCount = 1;
		presentInfo.pWaitSemaphores = signalSemaphores;
		VkSwapchainKHR swapChains[] = { swapChain };
		presentInfo.swapchainCount = 1;
		presentInfo.pSwapchains = swapChains;
		presentInfo.pImageIndices = &imageIndex;
		presentInfo.pResults = nullptr;

		result = vkQueuePresentKHR(presentQueue, &presentInfo);
		// remake swapchain before presenting if needed
		if (result == VK_ERROR_OUT_OF_DATE_KHR || result == VK_SUBOPTIMAL_KHR || framebufferResized) {
			framebufferResized = false;
			recreateSwapChain();
		}
		else if (result != VK_SUCCESS)
			throw std::runtime_error("failed to present swap chain image!");

		vkQueueWaitIdle(presentQueue);

		currentFrame = (currentFrame + 1) & MAX_FRAMES_IN_FLIGHT;
	}

	void updateUniformBuffer(uint32_t currentImage, RenderObject renderObject) {
		UniformBufferObject ubo{};
		ubo.model = renderObject.modelMatrix;
		ubo.view = glm::lookAt(glm::vec3(0.0f, 0.0f, zoomLevel), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f));
		ubo.proj = glm::perspective(glm::radians(45.0f), swapChainExtent.width / (float)swapChainExtent.height, 0.1f, 10.0f);
		ubo.proj[1][1] *= -1;	// was made for opengl which has Y coord inverted vs Vulkan

		if (!renderObject.shouldRender)
			ubo.model = glm::mat4(0.0f);

		void* data;
		vkMapMemory(device, renderObject.uniformBuffersMemory[currentImage], 0, sizeof(ubo), 0, &data);
		memcpy(data, &ubo, sizeof(ubo));
		vkUnmapMemory(device, renderObject.uniformBuffersMemory[currentImage]);
	}

	void updateUniformBufferUI(uint32_t currentImage, RenderObject renderObject) {
		float aspect = (float)swapChainExtent.width / (float)swapChainExtent.height;
		UniformBufferObject ubo{};
		ubo.model = glm::rotate(renderObject.modelMatrix, glm::radians(180.0f), glm::vec3(0.0f, 0.0f, 1.0f));
		ubo.view = glm::mat4(1.0f);
		ubo.proj = glm::ortho(-aspect, aspect, -1.0f, 1.0f);
		ubo.proj[1][1] *= -1;	// was made for opengl which has Y coord inverted vs Vulkan

		if (!renderObject.shouldRender)
			ubo.model = glm::mat4(0.0f);

		void* data;
		vkMapMemory(device, renderObject.uniformBuffersMemory[currentImage], 0, sizeof(ubo), 0, &data);
		memcpy(data, &ubo, sizeof(ubo));
		vkUnmapMemory(device, renderObject.uniformBuffersMemory[currentImage]);
	}

	void cleanup() {
		cleanupSwapChain();

		for (int i = 0; i < renderObjects.size(); i++) {
			vkDestroySampler(device, renderObjects[i].textureSampler, nullptr);
			vkDestroyImageView(device, renderObjects[i].textureImageView, nullptr);
			vkDestroyImage(device, renderObjects[i].textureImage, nullptr);
			vkFreeMemory(device, renderObjects[i].textureImageMemory, nullptr);
			vkDestroyBuffer(device, renderObjects[i].indexBuffer, nullptr);
			vkFreeMemory(device, renderObjects[i].indexBufferMemory, nullptr);
			vkDestroyBuffer(device, renderObjects[i].vertexBuffer, nullptr);
			vkFreeMemory(device, renderObjects[i].vertexBufferMemory, nullptr);
		}
		vkDestroyDescriptorSetLayout(device, descriptorSetLayout, nullptr);

		for (size_t i = 0; i < MAX_FRAMES_IN_FLIGHT; i++) {
			vkDestroySemaphore(device, renderFinishedSemaphores[i], nullptr);
			vkDestroySemaphore(device, imageAvailableSemaphores[i], nullptr);
			vkDestroyFence(device, inFlightFences[i], nullptr);
		}

		vkDestroyCommandPool(device, commandPool, nullptr);
		vkDestroyDevice(device, nullptr);
		vkDestroySurfaceKHR(instance, surface, nullptr);
		vkDestroyInstance(instance, nullptr);
		glfwDestroyWindow(window);
		glfwTerminate();
	}

	void cleanupSwapChain() {
		vkDestroyImageView(device, depthImageView, nullptr);
		vkDestroyImage(device, depthImage, nullptr);
		vkFreeMemory(device, depthImageMemory, nullptr);
		for (size_t i = 0; i < swapChainFramebuffers.size(); i++)
			vkDestroyFramebuffer(device, swapChainFramebuffers[i], nullptr);
		vkFreeCommandBuffers(device, commandPool, static_cast<uint32_t>(commandBuffers.size()), commandBuffers.data());
		vkDestroyPipeline(device, graphicsPipeline, nullptr);
		vkDestroyPipelineLayout(device, pipelineLayout, nullptr);
		vkDestroyRenderPass(device, renderPass, nullptr);
		for (auto imageView : swapChainImageViews)
			vkDestroyImageView(device, imageView, nullptr);
		vkDestroySwapchainKHR(device, swapChain, nullptr);
		for (int x = 0; x < renderObjects.size(); x++) {
			for (size_t i = 0; i < swapChainImages.size(); i++) {
				vkDestroyBuffer(device, renderObjects[x].uniformBuffers[i], nullptr);
				vkFreeMemory(device, renderObjects[x].uniformBuffersMemory[i], nullptr);
			}
			vkDestroyDescriptorPool(device, renderObjects[x].descriptorPool, nullptr);
		}
	}

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

		VkApplicationInfo appInfo = {};		//info to driver to optimize app
		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 = {};	//which global ext and avlidation layers to use
		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;
		createInfo.enabledLayerCount = 0;
		if (enableValidationLayers) {
			createInfo.enabledLayerCount = static_cast<uint32_t>(validationLayers.size());
			createInfo.ppEnabledLayerNames = validationLayers.data();
		}

		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:" << std::endl;
		//for (const auto& extension : extensions) {
		//	std::cout << "\t" << extension.extensionName << std::endl;
		//}
	}

	// check for all validation layers in vulkan to use in debugging
	bool checkValidationLayerSupport() {
		uint32_t layerCount;
		vkEnumerateInstanceLayerProperties(&layerCount, nullptr);
		std::vector<VkLayerProperties> availableLayers(layerCount);
		vkEnumerateInstanceLayerProperties(&layerCount, availableLayers.data());
		
		// check if all of the layers in validationLayers exist in the availableLayers list
		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 createSurface() {
		if (glfwCreateWindowSurface(instance, window, nullptr, &surface) != VK_SUCCESS)
			throw std::runtime_error("failed to create window surface!");
	}

	// pick gpu to use for vulkan
	void pickPhysicalDevice() {
		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());

		for (const auto& device : devices) {	// select first gpu that supports vulkan
			if (isDeviceSuitable(device)) {		// check device support for command queues and features
				physicalDevice = device;
				break;
			}
		}
		if (physicalDevice == VK_NULL_HANDLE)
			throw std::runtime_error("failed to find a suitable GPU!");
	}

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

		bool extensionsSupported = checkDeviceExtensionSupport(device);

		bool swapChainAdequate = false;
		if (extensionsSupported) {
			SwapChainSupportDetails swapChainSupport = querySwapChainSupport(device);
			swapChainAdequate = !swapChainSupport.formats.empty() && !swapChainSupport.presentModes.empty();
		}

		VkPhysicalDeviceFeatures supportedFeatures;
		vkGetPhysicalDeviceFeatures(device, &supportedFeatures);

		return indices.isComplete() && extensionsSupported && swapChainAdequate && supportedFeatures.samplerAnisotropy;
	}

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

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

	// check if device supports input command queues (graphics queue)
	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;

			VkBool32 presentSupport = false;
			vkGetPhysicalDeviceSurfaceSupportKHR(device, i, surface, &presentSupport);
			if (presentSupport)
				indices.presentFamily = i;

			i++;
		}

		return indices;
	}

	// check for swapchain compatibility 
	bool checkDeviceExtensionSupport(VkPhysicalDevice device) {
		uint32_t extensionCount;
		vkEnumerateDeviceExtensionProperties(device, nullptr, &extensionCount, nullptr);
		std::vector<VkExtensionProperties> availableExtensions(extensionCount);
		vkEnumerateDeviceExtensionProperties(device, nullptr, &extensionCount, availableExtensions.data());

		std::set<std::string> requiredExtensions(deviceExtensions.begin(), deviceExtensions.end());
		for (const auto& extension : availableExtensions)
			requiredExtensions.erase(extension.extensionName);

		return requiredExtensions.empty();
	}

	void createLogicalDevice() {
		QueueFamilyIndices indices = findQueueFamilies(physicalDevice);
		
		std::vector<VkDeviceQueueCreateInfo> queueCreateInfos;
		std::set<uint32_t> uniqueQueueFamilies = { indices.graphicsFamily.value(), indices.presentFamily.value() };
		float queuePriority = 1.0f;		// scheduling priority of queue [0.0, 1.0]
		for (uint32_t queueFamily : uniqueQueueFamilies) {
			VkDeviceQueueCreateInfo queueCreateInfo = {};
			queueCreateInfo.sType = VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO;
			queueCreateInfo.queueFamilyIndex = queueFamily;
			queueCreateInfo.queueCount = 1;
			queueCreateInfo.pQueuePriorities = &queuePriority;
			queueCreateInfos.push_back(queueCreateInfo);
		}

		VkPhysicalDeviceFeatures deviceFeatures = {};	// will be used for checking features

		VkDeviceCreateInfo createInfo = {};
		createInfo.sType = VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO;
		createInfo.queueCreateInfoCount = static_cast<uint32_t>(queueCreateInfos.size());
		createInfo.pQueueCreateInfos = queueCreateInfos.data();
		createInfo.pEnabledFeatures = &deviceFeatures;
		createInfo.enabledExtensionCount = static_cast<uint32_t>(deviceExtensions.size());
		createInfo.ppEnabledExtensionNames = deviceExtensions.data();
		createInfo.enabledLayerCount = 0;
		if (enableValidationLayers) {
			createInfo.enabledLayerCount = static_cast<uint32_t>(validationLayers.size());
			createInfo.ppEnabledLayerNames = validationLayers.data();
		} 

		if (vkCreateDevice(physicalDevice, &createInfo, nullptr, &device) != VK_SUCCESS)
			throw std::runtime_error("failed to create logical device!");

		vkGetDeviceQueue(device, indices.graphicsFamily.value(), 0, &graphicsQueue);
		vkGetDeviceQueue(device, indices.presentFamily.value(), 0, &presentQueue);
	}

	void createSwapChain() {
		SwapChainSupportDetails swapChainSupport = querySwapChainSupport(physicalDevice);

		VkSurfaceFormatKHR surfaceFormat = chooseSwapSurfaceFormat(swapChainSupport.formats);
		VkPresentModeKHR presentMode = chooseSwapPresentMode(swapChainSupport.presentModes);
		VkExtent2D extent = chooseSwapExtent(swapChainSupport.capabilities);

		uint32_t imageCount = swapChainSupport.capabilities.minImageCount + 1;		// images in swap chain ( +1 for no waiting if minimum)
		if (swapChainSupport.capabilities.maxImageCount > 0 && imageCount > swapChainSupport.capabilities.maxImageCount)	// dont exceed max ( 0 == no limit)
			imageCount = swapChainSupport.capabilities.maxImageCount;

		VkSwapchainCreateInfoKHR createInfo = {};
		createInfo.sType = VK_STRUCTURE_TYPE_SWAPCHAIN_CREATE_INFO_KHR;
		createInfo.surface = surface;
		createInfo.minImageCount = imageCount;
		createInfo.imageFormat = surfaceFormat.format;
		createInfo.imageColorSpace = surfaceFormat.colorSpace;
		createInfo.imageExtent = extent;
		createInfo.imageArrayLayers = 1;	// layers in image (always 1 unless steroscopic 3D)
		createInfo.imageUsage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT;	// specify operation on images (render directly to them)
		QueueFamilyIndices indices = findQueueFamilies(physicalDevice);
		uint32_t queueFamilyIndices[] = { indices.graphicsFamily.value(), indices.presentFamily.value() };
		if (indices.graphicsFamily != indices.presentFamily) {	// if not same, draw in graphics queue and submit to present queue
			createInfo.imageSharingMode = VK_SHARING_MODE_CONCURRENT;	// images can be used across queues without ownership transfer
			createInfo.queueFamilyIndexCount = 2;
			createInfo.pQueueFamilyIndices = queueFamilyIndices;
		} else {
			createInfo.imageSharingMode = VK_SHARING_MODE_EXCLUSIVE;	// image must be explicitly transfered to another queue family (best performance)
			createInfo.queueFamilyIndexCount = 0;		// optional
			createInfo.pQueueFamilyIndices = nullptr;	// optional
		}
		createInfo.preTransform = swapChainSupport.capabilities.currentTransform;	// can specify transformations (leave current)
		createInfo.compositeAlpha = VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR;		// can make window transparent (dont/opaque)
		createInfo.presentMode = presentMode;
		createInfo.clipped = VK_TRUE;	// dont care about obscured pixels (window in front of it)
		createInfo.oldSwapchain = VK_NULL_HANDLE;	// if swapchain becomes invalid (resize) recreate (we omit this functionality)

		if (vkCreateSwapchainKHR(device, &createInfo, nullptr, &swapChain) != VK_SUCCESS)
			throw std::runtime_error("failed to create swap chain!");

		// retrieve swap chain image handles
		vkGetSwapchainImagesKHR(device, swapChain, &imageCount, nullptr);
		swapChainImages.resize(imageCount);
		vkGetSwapchainImagesKHR(device, swapChain, &imageCount, swapChainImages.data());

		swapChainImageFormat = surfaceFormat.format;
		swapChainExtent = extent;
	}

	void recreateSwapChain() {
		// pause if window is minimized
		int width = 0, height = 0;
		glfwGetFramebufferSize(window, &width, &height);
		while (width == 0 || height == 0) {			// if minimized width/height == 0
			glfwGetFramebufferSize(window, &width, &height);
			glfwWaitEvents();
		}

		vkDeviceWaitIdle(device);	// dont touch resources that may still be in use

		cleanupSwapChain();

		createSwapChain();
		createImageViews();			// based directly on swap chain
		createRenderPass();			// based on swap chain image format
		createGraphicsPipeline();	// viewport and scissor rect are changed
		createDepthResources();
		createFramebuffers();		// depend directly on swapchain images
		for (int i = 0; i < renderObjects.size(); i++) {
			createUniformBuffers(renderObjects[i].uniformBuffers, renderObjects[i].uniformBuffersMemory);		// depends on number of swapchain images
			createDescriptorPool(renderObjects[i].descriptorPool);		// depends on number of swapchain images
			createDescriptorSets(renderObjects[i].descriptorSets, 
				renderObjects[i].descriptorPool, 
				renderObjects[i].uniformBuffers, 
				renderObjects[i].textureImageView, 
				renderObjects[i].textureSampler);		// depends on number of swapchain images
		}
		createCommandBuffers();		// depend directly on swapchain images
	}

	struct SwapChainSupportDetails {
		VkSurfaceCapabilitiesKHR capabilities;
		std::vector<VkSurfaceFormatKHR> formats;
		std::vector<VkPresentModeKHR> presentModes;
	};

	// check device for swapchain support
	SwapChainSupportDetails querySwapChainSupport(VkPhysicalDevice device) {
		SwapChainSupportDetails details;
		vkGetPhysicalDeviceSurfaceCapabilitiesKHR(device, surface, &details.capabilities);
		
		uint32_t formatCount;
		vkGetPhysicalDeviceSurfaceFormatsKHR(device, surface, &formatCount, nullptr);
		if (formatCount != 0) {
			details.formats.resize(formatCount);
			vkGetPhysicalDeviceSurfaceFormatsKHR(device, surface, &formatCount, details.formats.data());
		}

		uint32_t presentModeCount;
		vkGetPhysicalDeviceSurfacePresentModesKHR(device, surface, &presentModeCount, nullptr);
		if (presentModeCount != 0) {
			details.presentModes.resize(presentModeCount);
			vkGetPhysicalDeviceSurfacePresentModesKHR(device, surface, &presentModeCount, details.presentModes.data());
		}
		
		return details;
	}

	// choose 32 bit rgba color format if possible, else just get the first format in list
	VkSurfaceFormatKHR chooseSwapSurfaceFormat(const std::vector<VkSurfaceFormatKHR>& availableFormats) {
		for (const auto& availableFormat : availableFormats) {
			if (availableFormat.format == VK_FORMAT_B8G8R8A8_SRGB && availableFormat.colorSpace == VK_COLOR_SPACE_SRGB_NONLINEAR_KHR) {
				return availableFormat;
			}
		}
		return availableFormats[0];
	}

	// choose v-sync (garuanteed) or triple buffer if available
	VkPresentModeKHR chooseSwapPresentMode(const std::vector<VkPresentModeKHR>& availablePresentModes) {
		for (const auto& availablePresentMode : availablePresentModes) {
			if (availablePresentMode == VK_PRESENT_MODE_MAILBOX_KHR) {
				return availablePresentMode;
			}
		}
		return VK_PRESENT_MODE_FIFO_KHR;
	}

	// set resolution of swap chain images (size of window)
	VkExtent2D chooseSwapExtent(const VkSurfaceCapabilitiesKHR& capabilities) {
		if (capabilities.currentExtent.width != UINT32_MAX) {
			return capabilities.currentExtent;
		} else {
			int width, height;
			glfwGetFramebufferSize(window, &width, &height);

			VkExtent2D actualExtent = { static_cast<uint32_t>(width), static_cast<uint32_t>(height) };
			actualExtent.width = std::clamp(actualExtent.width, capabilities.minImageExtent.width, capabilities.maxImageExtent.width);
			actualExtent.height = std::clamp(actualExtent.height, capabilities.minImageExtent.height, capabilities.maxImageExtent.height);
			return actualExtent;
		}
	}

	void createImageViews() {
		swapChainImageViews.resize(swapChainImages.size());

		for (size_t i = 0; i < swapChainImages.size(); i++) {
			swapChainImageViews[i] = createImageView(swapChainImages[i], swapChainImageFormat, VK_IMAGE_ASPECT_COLOR_BIT);
		}
	}

	// specify framebuffer attachments for rendering wrapped in renderPass object
	void createRenderPass() {
		VkAttachmentDescription colorAttachment{};
		colorAttachment.format = swapChainImageFormat;
		colorAttachment.samples = VK_SAMPLE_COUNT_1_BIT;
		colorAttachment.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;	// clear values to constant at start
		colorAttachment.storeOp = VK_ATTACHMENT_STORE_OP_STORE;	// renders stored in memory and can be read later
		colorAttachment.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;	// we're not using stencil buffer
		colorAttachment.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;	// we're not using stencil buffer
		colorAttachment.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
		colorAttachment.finalLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR;	// images to be presented in swap chain
		VkAttachmentReference colorAttachmentRef{};
		colorAttachmentRef.attachment = 0;		// references index 0 of VkAttachmentDescription
		colorAttachmentRef.layout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;

		VkAttachmentDescription depthAttachment{};
		depthAttachment.format = findDepthFormat();
		depthAttachment.samples = VK_SAMPLE_COUNT_1_BIT;
		depthAttachment.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;
		depthAttachment.storeOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
		depthAttachment.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
		depthAttachment.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
		depthAttachment.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
		depthAttachment.finalLayout = VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL;
		VkAttachmentReference depthAttachmentRef{};
		depthAttachmentRef.attachment = 1;
		depthAttachmentRef.layout = VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL;

		VkSubpassDescription subpass{};
		subpass.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;
		subpass.colorAttachmentCount = 1;
		subpass.pColorAttachments = &colorAttachmentRef;
		subpass.pDepthStencilAttachment = &depthAttachmentRef;

		VkSubpassDependency dependency{};		// wait on swap chain to finish reading before accessing
		dependency.srcSubpass = VK_SUBPASS_EXTERNAL;
		dependency.dstSubpass = 0;
		dependency.srcStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
		dependency.srcAccessMask = 0;
		dependency.dstStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
		dependency.dstAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;

		std::array<VkAttachmentDescription, 2> attachments = { colorAttachment, depthAttachment };
		VkRenderPassCreateInfo renderPassInfo{};
		renderPassInfo.sType = VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO;
		renderPassInfo.attachmentCount = static_cast<uint32_t>(attachments.size());;
		renderPassInfo.pAttachments = attachments.data();
		renderPassInfo.subpassCount = 1;
		renderPassInfo.pSubpasses = &subpass;
		renderPassInfo.dependencyCount = 1;
		renderPassInfo.pDependencies = &dependency;		

		if (vkCreateRenderPass(device, &renderPassInfo, nullptr, &renderPass) != VK_SUCCESS)
			throw std::runtime_error("failed to create render pass!");
	}

	void createDescriptorSetLayout() {
		VkDescriptorSetLayoutBinding uboLayoutBinding{};
		uboLayoutBinding.binding = 0;		// the binding from shader
		uboLayoutBinding.descriptorType = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER;
		uboLayoutBinding.descriptorCount = 1;
		uboLayoutBinding.stageFlags = VK_SHADER_STAGE_VERTEX_BIT;		// which shader stage it will be referenced

		VkDescriptorSetLayoutBinding samplerLayoutBinding{};
		samplerLayoutBinding.binding = 1;
		samplerLayoutBinding.descriptorCount = 1;
		samplerLayoutBinding.descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER;
		samplerLayoutBinding.pImmutableSamplers = nullptr;
		samplerLayoutBinding.stageFlags = VK_SHADER_STAGE_FRAGMENT_BIT;

		std::array<VkDescriptorSetLayoutBinding, 2> bindings = { uboLayoutBinding, samplerLayoutBinding };
		VkDescriptorSetLayoutCreateInfo layoutInfo{};
		layoutInfo.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_LAYOUT_CREATE_INFO;
		layoutInfo.bindingCount = static_cast<uint32_t>(bindings.size());
		layoutInfo.pBindings = bindings.data();

		if (vkCreateDescriptorSetLayout(device, &layoutInfo, nullptr, &descriptorSetLayout) != VK_SUCCESS)
			throw std::runtime_error("failed to create descriptor set layout!");
	}

	// create graphics pipeline by loading shader files
	void createGraphicsPipeline() {
		auto vertShaderCode = readFile("shaders/vert.spv");
		auto fragShaderCode = readFile("shaders/frag.spv");
		VkShaderModule vertShaderModule = createShaderModule(vertShaderCode);
		VkShaderModule fragShaderModule = createShaderModule(fragShaderCode);

		VkPipelineShaderStageCreateInfo vertShaderStageInfo = {};
		vertShaderStageInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
		vertShaderStageInfo.stage = VK_SHADER_STAGE_VERTEX_BIT;
		vertShaderStageInfo.module = vertShaderModule;
		vertShaderStageInfo.pName = "main";		// entry point

		VkPipelineShaderStageCreateInfo fragShaderStageInfo = {};
		fragShaderStageInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
		fragShaderStageInfo.stage = VK_SHADER_STAGE_FRAGMENT_BIT;
		fragShaderStageInfo.module = fragShaderModule;
		fragShaderStageInfo.pName = "main";

		VkPipelineShaderStageCreateInfo shaderStages[] = { vertShaderStageInfo, fragShaderStageInfo };

		VkPipelineVertexInputStateCreateInfo vertexInputInfo{};
		vertexInputInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO;
		auto bindingDescription = Vertex::getBindingDescription();
		auto attributeDescriptions = Vertex::getAttributeDescriptions();
		vertexInputInfo.vertexBindingDescriptionCount = 1;
		vertexInputInfo.vertexAttributeDescriptionCount = static_cast<uint32_t>(attributeDescriptions.size());
		vertexInputInfo.pVertexBindingDescriptions = &bindingDescription;
		vertexInputInfo.pVertexAttributeDescriptions = attributeDescriptions.data();

		VkPipelineInputAssemblyStateCreateInfo inputAssembly{};
		inputAssembly.sType = VK_STRUCTURE_TYPE_PIPELINE_INPUT_ASSEMBLY_STATE_CREATE_INFO;
		inputAssembly.topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST;
		inputAssembly.primitiveRestartEnable = VK_FALSE;

		VkViewport viewport{};
		viewport.x = 0.0f;
		viewport.y = 0.0f;
		viewport.width = (float)swapChainExtent.width;
		viewport.height = (float)swapChainExtent.height;
		viewport.minDepth = 0.0f;
		viewport.maxDepth = 1.0f;

		VkRect2D scissor{};
		scissor.offset = { 0, 0 };
		scissor.extent = swapChainExtent;

		VkPipelineViewportStateCreateInfo viewportState{};
		viewportState.sType = VK_STRUCTURE_TYPE_PIPELINE_VIEWPORT_STATE_CREATE_INFO;
		viewportState.viewportCount = 1;
		viewportState.pViewports = &viewport;
		viewportState.scissorCount = 1;
		viewportState.pScissors = &scissor;

		VkPipelineRasterizationStateCreateInfo rasterizer{};
		rasterizer.sType = VK_STRUCTURE_TYPE_PIPELINE_RASTERIZATION_STATE_CREATE_INFO;
		rasterizer.depthClampEnable = VK_FALSE;				// if true clamp z depth frags instead of discard
		rasterizer.rasterizerDiscardEnable = VK_FALSE;		// if true disable rasterizer
		rasterizer.polygonMode = VK_POLYGON_MODE_FILL;
		rasterizer.lineWidth = 1.0f;						// wider than 1.0f requies wideLines gpu feature
		rasterizer.cullMode = VK_CULL_MODE_BACK_BIT;
		rasterizer.frontFace = VK_FRONT_FACE_COUNTER_CLOCKWISE;
		rasterizer.depthBiasEnable = VK_FALSE;

		VkPipelineMultisampleStateCreateInfo multisampling{};	// left disabled so far
		multisampling.sType = VK_STRUCTURE_TYPE_PIPELINE_MULTISAMPLE_STATE_CREATE_INFO;
		multisampling.sampleShadingEnable = VK_FALSE;
		multisampling.rasterizationSamples = VK_SAMPLE_COUNT_1_BIT;

		VkPipelineDepthStencilStateCreateInfo depthStencil{};
		depthStencil.sType = VK_STRUCTURE_TYPE_PIPELINE_DEPTH_STENCIL_STATE_CREATE_INFO;
		depthStencil.depthTestEnable = VK_TRUE;
		depthStencil.depthWriteEnable = VK_TRUE;
		depthStencil.depthCompareOp = VK_COMPARE_OP_LESS;
		depthStencil.depthBoundsTestEnable = VK_FALSE;
		depthStencil.minDepthBounds = 0.0f; // Optional
		depthStencil.maxDepthBounds = 1.0f; // Optional
		depthStencil.stencilTestEnable = VK_FALSE;

		VkPipelineColorBlendAttachmentState colorBlendAttachment{};		// left disabled, blends new and old rasterized pixel per framebuffer
		colorBlendAttachment.colorWriteMask = VK_COLOR_COMPONENT_R_BIT | VK_COLOR_COMPONENT_G_BIT | VK_COLOR_COMPONENT_B_BIT | VK_COLOR_COMPONENT_A_BIT;
		colorBlendAttachment.blendEnable = VK_FALSE;

		VkPipelineColorBlendStateCreateInfo colorBlending{};		// left disabled, blends new and old rasterized pixel for every frambuffer, overrides prev blend
		colorBlending.sType = VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_STATE_CREATE_INFO;
		colorBlending.logicOpEnable = VK_FALSE;
		colorBlending.logicOp = VK_LOGIC_OP_COPY; // Optional
		colorBlending.attachmentCount = 1;
		colorBlending.pAttachments = &colorBlendAttachment;
		colorBlending.blendConstants[0] = 0.0f; // Optional
		colorBlending.blendConstants[1] = 0.0f; // Optional
		colorBlending.blendConstants[2] = 0.0f; // Optional
		colorBlending.blendConstants[3] = 0.0f; // Optional

		VkPipelineLayoutCreateInfo pipelineLayoutInfo{};
		pipelineLayoutInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO;
		pipelineLayoutInfo.setLayoutCount = 1;
		pipelineLayoutInfo.pSetLayouts = &descriptorSetLayout;

		if (vkCreatePipelineLayout(device, &pipelineLayoutInfo, nullptr, &pipelineLayout) != VK_SUCCESS)
			throw std::runtime_error("failed to create pipeline layout!");

		VkGraphicsPipelineCreateInfo pipelineInfo{};
		pipelineInfo.sType = VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO;
		pipelineInfo.stageCount = 2;
		pipelineInfo.pStages = shaderStages;
		pipelineInfo.pVertexInputState = &vertexInputInfo;
		pipelineInfo.pInputAssemblyState = &inputAssembly;
		pipelineInfo.pViewportState = &viewportState;
		pipelineInfo.pRasterizationState = &rasterizer;
		pipelineInfo.pMultisampleState = &multisampling;
		pipelineInfo.pDepthStencilState = &depthStencil;
		pipelineInfo.pColorBlendState = &colorBlending;
		pipelineInfo.layout = pipelineLayout;
		pipelineInfo.renderPass = renderPass;
		pipelineInfo.subpass = 0;
		pipelineInfo.basePipelineHandle = VK_NULL_HANDLE;	// for deriving new pipeline from another
		pipelineInfo.basePipelineIndex = -1;				// for deriving new pipeline from another

		if (vkCreateGraphicsPipelines(device, VK_NULL_HANDLE, 1, &pipelineInfo, nullptr, &graphicsPipeline) != VK_SUCCESS)
			throw std::runtime_error("failed to create graphics pipeline!");

		vkDestroyShaderModule(device, vertShaderModule, nullptr);
		vkDestroyShaderModule(device, fragShaderModule, nullptr);
	}

	// read file as binary
	static std::vector<char> readFile(const std::string& filename) {
		std::ifstream file(filename, std::ios::ate | std::ios::binary);	// start AtTheEnd to get size of file
		if (!file.is_open())
			throw std::runtime_error("failed to open file!" + filename);

		size_t fileSize = (size_t)file.tellg();
		std::vector<char> buffer(fileSize);
		file.seekg(0);
		file.read(buffer.data(), fileSize);
		file.close();

		std::cout << "filesize " << fileSize << "\n";

		return buffer;
	}

	// wrap a shader byte code in vulkan object and return
	VkShaderModule createShaderModule(const std::vector<char>& code) {
		VkShaderModuleCreateInfo createInfo = {};
		createInfo.sType = VK_STRUCTURE_TYPE_SHADER_MODULE_CREATE_INFO;
		createInfo.codeSize = code.size();
		createInfo.pCode = reinterpret_cast<const uint32_t*>(code.data());	// must convert from char* to uint32_t*

		VkShaderModule shaderModule;
		if (vkCreateShaderModule(device, &createInfo, nullptr, &shaderModule) != VK_SUCCESS)
			throw std::runtime_error("failed to create shader module!");
		return shaderModule;
	}

	void createFramebuffers() {
		swapChainFramebuffers.resize(swapChainImageViews.size());
		for (size_t i = 0; i < swapChainImageViews.size(); i++) {
			std::array<VkImageView, 2> attachments = {
				swapChainImageViews[i],
				depthImageView
			};
			VkFramebufferCreateInfo framebufferInfo{};
			framebufferInfo.sType = VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO;
			framebufferInfo.renderPass = renderPass;
			framebufferInfo.attachmentCount = static_cast<uint32_t>(attachments.size());;
			framebufferInfo.pAttachments = attachments.data();
			framebufferInfo.width = swapChainExtent.width;
			framebufferInfo.height = swapChainExtent.height;
			framebufferInfo.layers = 1;

			if (vkCreateFramebuffer(device, &framebufferInfo, nullptr, &swapChainFramebuffers[i]) != VK_SUCCESS)
				throw std::runtime_error("failed to create framebuffer!");
		}
	}

	void createCommandPool() {
		QueueFamilyIndices queueFamilyIndices = findQueueFamilies(physicalDevice);

		VkCommandPoolCreateInfo poolInfo{};
		poolInfo.sType = VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO;
		poolInfo.queueFamilyIndex = queueFamilyIndices.graphicsFamily.value();
		if (vkCreateCommandPool(device, &poolInfo, nullptr, &commandPool) != VK_SUCCESS)
			throw std::runtime_error("failed to create command pool");
	}

	void createDepthResources() {
		VkFormat depthFormat = findDepthFormat();
		createImage(swapChainExtent.width, swapChainExtent.height, depthFormat, VK_IMAGE_TILING_OPTIMAL, VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT, depthImage, depthImageMemory);
		depthImageView = createImageView(depthImage, depthFormat, VK_IMAGE_ASPECT_DEPTH_BIT);
	}

	VkFormat findDepthFormat() {
		return findSupportedFormat(
			{ VK_FORMAT_D32_SFLOAT, VK_FORMAT_D32_SFLOAT_S8_UINT, VK_FORMAT_D24_UNORM_S8_UINT },
			VK_IMAGE_TILING_OPTIMAL,
			VK_FORMAT_FEATURE_DEPTH_STENCIL_ATTACHMENT_BIT
		);
	}

	VkFormat findSupportedFormat(const std::vector<VkFormat>& candidates, VkImageTiling tiling, VkFormatFeatureFlags features) {
		for (VkFormat format : candidates) {
			VkFormatProperties props;
			vkGetPhysicalDeviceFormatProperties(physicalDevice, format, &props);

			if (tiling == VK_IMAGE_TILING_LINEAR && (props.linearTilingFeatures & features) == features) {
				return format;
			}
			else if (tiling == VK_IMAGE_TILING_OPTIMAL && (props.optimalTilingFeatures & features) == features) {
				return format;
			}
		}

		throw std::runtime_error("failed to find supported format!");
	}

	bool hasStencilComponent(VkFormat format) {
		return format == VK_FORMAT_D32_SFLOAT_S8_UINT || format == VK_FORMAT_D24_UNORM_S8_UINT;
	}

	void createTextureImage(VkImage& textureImage, VkDeviceMemory& textureImageMemory, std::string imagePath) {
		// load jpg from disk to ram
		int texWidth, texHeight, texChannels;
		stbi_uc* pixels = stbi_load(imagePath.c_str(), &texWidth, &texHeight, &texChannels, STBI_rgb_alpha);
		VkDeviceSize imageSize = texWidth * texHeight * 4;
		if (!pixels)
			throw std::runtime_error("failed to load texture image!");

		// load from ram to cpu accessable gpu memory
		VkBuffer stagingBuffer;
		VkDeviceMemory stagingBufferMemory;
		createBuffer(imageSize, VK_BUFFER_USAGE_TRANSFER_SRC_BIT, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT, stagingBuffer, stagingBufferMemory);

		void* data;
		vkMapMemory(device, stagingBufferMemory, 0, imageSize, 0, &data);
		memcpy(data, pixels, static_cast<size_t>(imageSize));
		vkUnmapMemory(device, stagingBufferMemory);
		stbi_image_free(pixels);

		createImage(texWidth, texHeight, VK_FORMAT_R8G8B8A8_SRGB, VK_IMAGE_TILING_OPTIMAL, VK_IMAGE_USAGE_TRANSFER_DST_BIT | VK_IMAGE_USAGE_SAMPLED_BIT, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT, textureImage, textureImageMemory);
		transitionImageLayout(textureImage, VK_FORMAT_R8G8B8A8_SRGB, VK_IMAGE_LAYOUT_UNDEFINED, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL);
		copyBufferToImage(stagingBuffer, textureImage, static_cast<uint32_t>(texWidth), static_cast<uint32_t>(texHeight));
		transitionImageLayout(textureImage, VK_FORMAT_R8G8B8A8_SRGB, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL);

		vkDestroyBuffer(device, stagingBuffer, nullptr);
		vkFreeMemory(device, stagingBufferMemory, nullptr);
	}

	void createImage(uint32_t width, uint32_t height, VkFormat format, VkImageTiling tiling, VkImageUsageFlags usage, VkMemoryPropertyFlags properties, VkImage& image, VkDeviceMemory& imageMemory) {
		VkImageCreateInfo imageInfo{};
		imageInfo.sType = VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO;
		imageInfo.imageType = VK_IMAGE_TYPE_2D;
		imageInfo.extent.width = width;
		imageInfo.extent.height = height;
		imageInfo.extent.depth = 1;
		imageInfo.mipLevels = 1;
		imageInfo.arrayLayers = 1;
		imageInfo.format = format;
		imageInfo.tiling = tiling;
		imageInfo.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
		imageInfo.usage = usage;
		imageInfo.samples = VK_SAMPLE_COUNT_1_BIT;
		imageInfo.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
		if (vkCreateImage(device, &imageInfo, nullptr, &image) != VK_SUCCESS)
			throw std::runtime_error("failed to create image!");

		VkMemoryRequirements memRequirements;
		vkGetImageMemoryRequirements(device, image, &memRequirements);
		VkMemoryAllocateInfo allocInfo{};
		allocInfo.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
		allocInfo.allocationSize = memRequirements.size;
		allocInfo.memoryTypeIndex = findMemoryType(memRequirements.memoryTypeBits, properties);
		if (vkAllocateMemory(device, &allocInfo, nullptr, &imageMemory) != VK_SUCCESS)
			throw std::runtime_error("failed to allocate image memory!");
		vkBindImageMemory(device, image, imageMemory, 0);
	}

	// set image buffer to be in right format before putting in VkImage
	void transitionImageLayout(VkImage image, VkFormat format, VkImageLayout oldLayout, VkImageLayout newLayout) {
		VkCommandBuffer commandBuffer = beginSingleTimeCommands();

		VkImageMemoryBarrier barrier{};		// syncronize access to resource
		barrier.sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER;
		barrier.oldLayout = oldLayout;
		barrier.newLayout = newLayout;
		barrier.srcQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
		barrier.dstQueueFamilyIndex = VK_QUEUE_FAMILY_IGNORED;
		barrier.image = image;
		barrier.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
		barrier.subresourceRange.baseMipLevel = 0;
		barrier.subresourceRange.levelCount = 1;
		barrier.subresourceRange.baseArrayLayer = 0;
		barrier.subresourceRange.layerCount = 1;
		VkPipelineStageFlags sourceStage;
		VkPipelineStageFlags destinationStage;

		if (oldLayout == VK_IMAGE_LAYOUT_UNDEFINED && newLayout == VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL) {
			barrier.srcAccessMask = 0;
			barrier.dstAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT;

			sourceStage = VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT;
			destinationStage = VK_PIPELINE_STAGE_TRANSFER_BIT;
		}
		else if (oldLayout == VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL && newLayout == VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL) {
			barrier.srcAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT;
			barrier.dstAccessMask = VK_ACCESS_SHADER_READ_BIT;

			sourceStage = VK_PIPELINE_STAGE_TRANSFER_BIT;
			destinationStage = VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT;
		}
		else {
			throw std::invalid_argument("unsupported image layout transition!");
		}

		vkCmdPipelineBarrier(commandBuffer, sourceStage, destinationStage, 0, 0, nullptr, 0, nullptr, 1, &barrier);

		endSingleTimeCommands(commandBuffer);
	}

	void copyBufferToImage(VkBuffer buffer, VkImage image, uint32_t width, uint32_t height) {
		VkCommandBuffer commandBuffer = beginSingleTimeCommands();

		VkBufferImageCopy region{};
		region.bufferOffset = 0;
		region.bufferRowLength = 0;
		region.bufferImageHeight = 0;
		region.imageSubresource.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
		region.imageSubresource.mipLevel = 0;
		region.imageSubresource.baseArrayLayer = 0;
		region.imageSubresource.layerCount = 1;
		region.imageOffset = { 0, 0, 0 };
		region.imageExtent = { width, height, 1	};
		vkCmdCopyBufferToImage(commandBuffer, buffer, image, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, 1, &region);

		endSingleTimeCommands(commandBuffer);

	}

	void createTextureImageView(VkImageView& textureImageView, VkImage& textureImage) {
		textureImageView = createImageView(textureImage, VK_FORMAT_R8G8B8A8_SRGB, VK_IMAGE_ASPECT_COLOR_BIT);
	}

	// create distinct object to extract colors from texture
	void createTextureSampler(VkSampler& textureSampler) {
		VkSamplerCreateInfo samplerInfo{};
		samplerInfo.sType = VK_STRUCTURE_TYPE_SAMPLER_CREATE_INFO;
		samplerInfo.magFilter = VK_FILTER_LINEAR;
		samplerInfo.minFilter = VK_FILTER_LINEAR;
		samplerInfo.addressModeU = VK_SAMPLER_ADDRESS_MODE_REPEAT;
		samplerInfo.addressModeV = VK_SAMPLER_ADDRESS_MODE_REPEAT;
		samplerInfo.addressModeW = VK_SAMPLER_ADDRESS_MODE_REPEAT;
		samplerInfo.anisotropyEnable = VK_FALSE;
		samplerInfo.maxAnisotropy = 16;
		samplerInfo.borderColor = VK_BORDER_COLOR_INT_OPAQUE_BLACK;
		samplerInfo.unnormalizedCoordinates = VK_FALSE;		// we use normalized [0, 1)
		samplerInfo.compareEnable = VK_FALSE;
		samplerInfo.compareOp = VK_COMPARE_OP_ALWAYS;
		samplerInfo.mipmapMode = VK_SAMPLER_MIPMAP_MODE_LINEAR;

		if (vkCreateSampler(device, &samplerInfo, nullptr, &textureSampler) != VK_SUCCESS)
			throw std::runtime_error("failed to create texture sampler!");
	}

	VkImageView createImageView(VkImage image, VkFormat format, VkImageAspectFlags aspectFlags) {
		VkImageViewCreateInfo viewInfo{};
		viewInfo.sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO;
		viewInfo.image = image;
		viewInfo.viewType = VK_IMAGE_VIEW_TYPE_2D;
		viewInfo.format = format;
		viewInfo.subresourceRange.aspectMask = aspectFlags;
		viewInfo.subresourceRange.baseMipLevel = 0;
		viewInfo.subresourceRange.levelCount = 1;
		viewInfo.subresourceRange.baseArrayLayer = 0;
		viewInfo.subresourceRange.layerCount = 1;

		VkImageView imageView;
		if (vkCreateImageView(device, &viewInfo, nullptr, &imageView) != VK_SUCCESS) {
			throw std::runtime_error("failed to create texture image view!");
		}

		return imageView;
	}

	// load an obj model into array of vertices, etc.
	void loadModel(std::vector<Vertex>& vertices, std::vector<uint32_t>& indices, std::string modelPath) {
		tinyobj::attrib_t attrib;
		std::vector<tinyobj::shape_t> shapes;
		std::vector<tinyobj::material_t> materials;
		std::string warn, err;

		if (!tinyobj::LoadObj(&attrib, &shapes, &materials, &warn, &err, modelPath.c_str())) {
			throw std::runtime_error(warn + err);
		}

		for (const auto& shape : shapes) {
			for (const auto& index : shape.mesh.indices) {
				Vertex vertex{};

				vertex.pos = {
					attrib.vertices[3 * index.vertex_index + 0],
					attrib.vertices[3 * index.vertex_index + 1],
					attrib.vertices[3 * index.vertex_index + 2]
				};

				vertex.texCoord = {
					attrib.texcoords[2 * index.texcoord_index + 0],
					1.0f - attrib.texcoords[2 * index.texcoord_index + 1]
				};

				//vertex.color = { 1.0f, 1.0f, 1.0f };
				vertex.color = { 
					attrib.normals[3 * index.normal_index + 0], 
					attrib.normals[3 * index.normal_index + 1],
					attrib.normals[3 * index.normal_index + 2]
				};

				vertices.push_back(vertex);

				indices.push_back(indices.size());
			}
		}
	}

	void createVertexBuffer(VkBuffer& vertexBuffer, VkDeviceMemory& vertexBufferMemory, std::vector<Vertex>& vertices) {
		VkDeviceSize bufferSize = sizeof(vertices[0]) * vertices.size();

		// create cpu accessable staging vertex buffer
		VkBuffer stagingBuffer;
		VkDeviceMemory stagingBufferMemory;
		createBuffer(bufferSize, VK_BUFFER_USAGE_TRANSFER_SRC_BIT, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT, stagingBuffer, stagingBufferMemory);

		// fill memory with data
		void* data;		// cpu accessable memory
		vkMapMemory(device, stagingBufferMemory, 0, bufferSize, 0, &data);
		memcpy(data, vertices.data(), (size_t)bufferSize);
		vkUnmapMemory(device, stagingBufferMemory);

		// create gpu only accessable vertex buffer
		createBuffer(bufferSize, VK_BUFFER_USAGE_TRANSFER_DST_BIT | VK_BUFFER_USAGE_VERTEX_BUFFER_BIT, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT, vertexBuffer, vertexBufferMemory);
		copyBuffer(stagingBuffer, vertexBuffer, bufferSize);

		vkDestroyBuffer(device, stagingBuffer, nullptr);
		vkFreeMemory(device, stagingBufferMemory, nullptr);
	}

	void createIndexBuffer(VkBuffer& indexBuffer, VkDeviceMemory& indexBufferMemory, std::vector<uint32_t>& indices) {
		VkDeviceSize bufferSize = sizeof(indices[0]) * indices.size();

		VkBuffer stagingBuffer;
		VkDeviceMemory stagingBufferMemory;
		createBuffer(bufferSize, VK_BUFFER_USAGE_TRANSFER_SRC_BIT, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT, stagingBuffer, stagingBufferMemory);

		void* data;
		vkMapMemory(device, stagingBufferMemory, 0, bufferSize, 0, &data);
		memcpy(data, indices.data(), (size_t)bufferSize);
		vkUnmapMemory(device, stagingBufferMemory);

		createBuffer(bufferSize, VK_BUFFER_USAGE_TRANSFER_DST_BIT | VK_BUFFER_USAGE_INDEX_BUFFER_BIT, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT, indexBuffer, indexBufferMemory);
		copyBuffer(stagingBuffer, indexBuffer, bufferSize);

		vkDestroyBuffer(device, stagingBuffer, nullptr);
		vkFreeMemory(device, stagingBufferMemory, nullptr);
	}

	void createUniformBuffers(std::vector<VkBuffer>& uniformBuffers, std::vector<VkDeviceMemory>& uniformBuffersMemory) {
		VkDeviceSize bufferSize = sizeof(UniformBufferObject);

		uniformBuffers.resize(swapChainImages.size());
		uniformBuffersMemory.resize(swapChainImages.size());

		for (size_t i = 0; i < swapChainImages.size(); i++) {
			createBuffer(bufferSize, VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT, uniformBuffers[i], uniformBuffersMemory[i]);
		}
	}

	void createDescriptorPool(VkDescriptorPool& descriptorPool) {
		std::array<VkDescriptorPoolSize, 2> poolSizes{};
		poolSizes[0].type = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER;
		poolSizes[0].descriptorCount = static_cast<uint32_t>(swapChainImages.size());
		poolSizes[1].type = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER;
		poolSizes[1].descriptorCount = static_cast<uint32_t>(swapChainImages.size());

		VkDescriptorPoolCreateInfo poolInfo{};
		poolInfo.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_POOL_CREATE_INFO;
		poolInfo.poolSizeCount = static_cast<uint32_t>(poolSizes.size());
		poolInfo.pPoolSizes = poolSizes.data();
		poolInfo.maxSets = static_cast<uint32_t>(swapChainImages.size());

		if (vkCreateDescriptorPool(device, &poolInfo, nullptr, &descriptorPool) != VK_SUCCESS)
			throw std::runtime_error("failed to create descriptor pool!");
	}

	// configures information for rendering object like MVP and texture
	void createDescriptorSets(std::vector<VkDescriptorSet>& descriptorSets, VkDescriptorPool& descriptorPool, std::vector<VkBuffer>& uniformBuffers, VkImageView& textureImageView, VkSampler& textureSampler) {
		std::vector<VkDescriptorSetLayout> layouts(swapChainImages.size(), descriptorSetLayout);
		VkDescriptorSetAllocateInfo allocInfo{};
		allocInfo.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_ALLOCATE_INFO;
		allocInfo.descriptorPool = descriptorPool;
		allocInfo.descriptorSetCount = static_cast<uint32_t>(swapChainImages.size());
		allocInfo.pSetLayouts = layouts.data();
		descriptorSets.resize(swapChainImages.size());
		if (vkAllocateDescriptorSets(device, &allocInfo, descriptorSets.data()) != VK_SUCCESS)
			throw std::runtime_error("failed to allocate descriptor sets!");

		// configure descriptors
		for (size_t i = 0; i < swapChainImages.size(); i++) {
			VkDescriptorBufferInfo bufferInfo{};
			bufferInfo.buffer = uniformBuffers[i];
			bufferInfo.offset = 0;
			bufferInfo.range = sizeof(UniformBufferObject);

			VkDescriptorImageInfo imageInfo{};
			imageInfo.imageLayout = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
			imageInfo.imageView = textureImageView;
			imageInfo.sampler = textureSampler;

			std::array<VkWriteDescriptorSet, 2> descriptorWrites{};

			descriptorWrites[0].sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET;
			descriptorWrites[0].dstSet = descriptorSets[i];
			descriptorWrites[0].dstBinding = 0;
			descriptorWrites[0].dstArrayElement = 0;
			descriptorWrites[0].descriptorType = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER;
			descriptorWrites[0].descriptorCount = 1;
			descriptorWrites[0].pBufferInfo = &bufferInfo;

			descriptorWrites[1].sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET;
			descriptorWrites[1].dstSet = descriptorSets[i];
			descriptorWrites[1].dstBinding = 1;
			descriptorWrites[1].dstArrayElement = 0;
			descriptorWrites[1].descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER;
			descriptorWrites[1].descriptorCount = 1;
			descriptorWrites[1].pImageInfo = &imageInfo;

			vkUpdateDescriptorSets(device, static_cast<uint32_t>(descriptorWrites.size()), descriptorWrites.data(), 0, nullptr);
		}
	}

	void createBuffer(VkDeviceSize size, VkBufferUsageFlags usage, VkMemoryPropertyFlags properties, VkBuffer& buffer, VkDeviceMemory& bufferMemory) {
		// allocate buffer
		VkBufferCreateInfo bufferInfo{};
		bufferInfo.sType = VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO;
		bufferInfo.size = size;
		bufferInfo.usage = usage;
		bufferInfo.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
		if (vkCreateBuffer(device, &bufferInfo, nullptr, &buffer) != VK_SUCCESS)
			throw std::runtime_error("failed to create vertex buffer!");

		// allocate memory in gpu
		VkMemoryRequirements memRequirements;
		vkGetBufferMemoryRequirements(device, buffer, &memRequirements);
		VkMemoryAllocateInfo allocInfo{};
		allocInfo.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
		allocInfo.allocationSize = memRequirements.size;
		allocInfo.memoryTypeIndex = findMemoryType(memRequirements.memoryTypeBits, properties);
		if (vkAllocateMemory(device, &allocInfo, nullptr, &bufferMemory) != VK_SUCCESS)
			throw std::runtime_error("failed to allocate vertex buffer memory!");

		// bind buffer to allocated memory
		vkBindBufferMemory(device, buffer, bufferMemory, 0);
	}

	uint32_t findMemoryType(uint32_t typeFilter, VkMemoryPropertyFlags properties) {
		VkPhysicalDeviceMemoryProperties memProperties;
		vkGetPhysicalDeviceMemoryProperties(physicalDevice, &memProperties);
		// find memory that is (suiatable for vertex data) && (CPU can write to it)
		for (uint32_t i = 0; i < memProperties.memoryTypeCount; i++) {
			if ((typeFilter & (1 << i)) && (memProperties.memoryTypes[i].propertyFlags & properties) == properties) {
				return i;
			}
		}
		throw std::runtime_error("failed to find suitable memory type!");
	}

	// copy data from one buffer to another buffer
	void copyBuffer(VkBuffer srcBuffer, VkBuffer dstBuffer, VkDeviceSize size) {
		VkCommandBuffer commandBuffer = beginSingleTimeCommands();

		VkBufferCopy copyRegion{};
		copyRegion.size = size;
		vkCmdCopyBuffer(commandBuffer, srcBuffer, dstBuffer, 1, &copyRegion);

		endSingleTimeCommands(commandBuffer);
	}

	// create rendering command  buffers
	void createCommandBuffers() {
		commandBuffers.resize(swapChainFramebuffers.size());

		VkCommandBufferAllocateInfo allocInfo{};
		allocInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO;
		allocInfo.commandPool = commandPool;
		allocInfo.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY;
		allocInfo.commandBufferCount = (uint32_t)commandBuffers.size();
		if (vkAllocateCommandBuffers(device, &allocInfo, commandBuffers.data()) != VK_SUCCESS)
			throw std::runtime_error("failed to allocate command buffers!");

		for (size_t i = 0; i < commandBuffers.size(); i++) {
			VkCommandBufferBeginInfo beginInfo{};
			beginInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;
			beginInfo.flags = 0;
			beginInfo.pInheritanceInfo = nullptr;
			if (vkBeginCommandBuffer(commandBuffers[i], &beginInfo) != VK_SUCCESS)
				throw std::runtime_error("failed to begin recording command buffer!");

			VkRenderPassBeginInfo renderPassInfo{};
			renderPassInfo.sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO;
			renderPassInfo.renderPass = renderPass;
			renderPassInfo.framebuffer = swapChainFramebuffers[i];
			renderPassInfo.renderArea.offset = { 0, 0 };
			renderPassInfo.renderArea.extent = swapChainExtent;
			std::array<VkClearValue, 2> clearValues{};
			clearValues[0].color = { 0.0f, 0.0f, 0.0f, 1.0f };
			clearValues[1].depthStencil = { 1.0f, 0 };
			VkClearValue clearColor = { 0.0f, 0.0f, 0.0f, 1.0f };
			renderPassInfo.clearValueCount = static_cast<uint32_t>(clearValues.size());
			renderPassInfo.pClearValues = clearValues.data();

			vkCmdBeginRenderPass(commandBuffers[i], &renderPassInfo, VK_SUBPASS_CONTENTS_INLINE);
			vkCmdBindPipeline(commandBuffers[i], VK_PIPELINE_BIND_POINT_GRAPHICS, graphicsPipeline);

			VkBuffer vertexBuffers[] = { renderObjects[0].vertexBuffer };
			VkDeviceSize offsets[] = { 0 };

			for (int x = 0; x < renderObjects.size(); x++) {
				vertexBuffers[0] = renderObjects[x].vertexBuffer;
				vkCmdBindVertexBuffers(commandBuffers[i], 0, 1, vertexBuffers, offsets);
				vkCmdBindIndexBuffer(commandBuffers[i], renderObjects[x].indexBuffer, 0, VK_INDEX_TYPE_UINT32);
				vkCmdBindDescriptorSets(commandBuffers[i], VK_PIPELINE_BIND_POINT_GRAPHICS, pipelineLayout, 0, 1, &renderObjects[x].descriptorSets[i], 0, nullptr);
				vkCmdDrawIndexed(commandBuffers[i], static_cast<uint32_t>(renderObjects[x].indices.size()), 1, 0, 0, 0);
			}

			vkCmdEndRenderPass(commandBuffers[i]);
			if (vkEndCommandBuffer(commandBuffers[i]) != VK_SUCCESS)
				throw std::runtime_error("failed to record command buffer!");
		}
	}

	// create one time command into pool/buffer (ex to copy staging memory to gpu memory)
	VkCommandBuffer beginSingleTimeCommands() {
		VkCommandBufferAllocateInfo allocInfo{};
		allocInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO;
		allocInfo.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY;
		allocInfo.commandPool = commandPool;
		allocInfo.commandBufferCount = 1;

		VkCommandBuffer commandBuffer;
		vkAllocateCommandBuffers(device, &allocInfo, &commandBuffer);

		VkCommandBufferBeginInfo beginInfo{};
		beginInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;
		beginInfo.flags = VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT;

		vkBeginCommandBuffer(commandBuffer, &beginInfo);

		return commandBuffer;
	}

	// clean up single use command
	void endSingleTimeCommands(VkCommandBuffer commandBuffer) {
		vkEndCommandBuffer(commandBuffer);

		VkSubmitInfo submitInfo{};
		submitInfo.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;
		submitInfo.commandBufferCount = 1;
		submitInfo.pCommandBuffers = &commandBuffer;

		vkQueueSubmit(graphicsQueue, 1, &submitInfo, VK_NULL_HANDLE);
		vkQueueWaitIdle(graphicsQueue);

		vkFreeCommandBuffers(device, commandPool, 1, &commandBuffer);
	}

	// create semaphores/fences for syncronizing frame swap rendering
	void createSyncObjects() {
		imageAvailableSemaphores.resize(MAX_FRAMES_IN_FLIGHT);
		renderFinishedSemaphores.resize(MAX_FRAMES_IN_FLIGHT);
		inFlightFences.resize(MAX_FRAMES_IN_FLIGHT);
		imagesInFlight.resize(swapChainImages.size(), VK_NULL_HANDLE);

		VkSemaphoreCreateInfo semaphoreInfo{};
		semaphoreInfo.sType = VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO;

		VkFenceCreateInfo fenceInfo{};
		fenceInfo.sType = VK_STRUCTURE_TYPE_FENCE_CREATE_INFO;
		fenceInfo.flags = VK_FENCE_CREATE_SIGNALED_BIT;		// initial frame is ready on creation (by default?)

		for (size_t i = 0; i < MAX_FRAMES_IN_FLIGHT; i++) {
			if (vkCreateSemaphore(device, &semaphoreInfo, nullptr, &imageAvailableSemaphores[i]) != VK_SUCCESS ||
				vkCreateSemaphore(device, &semaphoreInfo, nullptr, &renderFinishedSemaphores[i]) != VK_SUCCESS ||
				vkCreateFence(device, &fenceInfo, nullptr, &inFlightFences[i]) != VK_SUCCESS)
				throw std::runtime_error("failed to create render semaphores!");
		}
	}

	
};

int main() {
	HelloTriangleApplication app;

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

	return EXIT_SUCCESS;
}