原文地址:vulkan-tutorial
Base code
General structure
上一章通過構建一個窗體來完成VS對Vulkan的配置,並將配置好的工程設置爲模板以備後續的使用。在上一章的最後我們用這個模板創建了一個名爲:Hello Triangle 的新工程,現在讓我們爲這個工程搭建一個框架。
#include <iostream>
#include <stdexcept>
#include <functional>
class HelloTriangleApplication {
public:
void run() {
initVulkan();
mainLoop();
}
private:
void initVulkan() {
}
void mainLoop() {
}
};
int main() {
HelloTriangleApplication app;
try {
app.run();
} catch (const std::runtime_error& e) {
std::cerr << e.what() << std::endl;
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}
stdexception 引入異常,functional 引入lambda功能。
Resource management
每一個Vulkan對象不再使用後,都需要用一個清理函數來銷燬,就像malloc 分配的內存要用free 銷燬一樣。手動來銷燬每一個對象是一個非常繁雜且容易出錯的任務。我們利用C++的RAII原理來創建一個包裹類,當對象離開有效作用域後自動爲我們銷燬對象。如下,在創建VkInstance前,用類似方法聲明VkInstance對象,並告訴我們的包裹類,銷燬Instance對象的方法是vkDestroyInstance:
VDeleter<VkInstance> instance{vkDestroyInstance}; //VDeleter是我們的包裹類。
然後創建這個Instance:
vkCreateInstance(&instanceCreateInfo, nullptr, &instance);
當Instance離開有效作用域,比如,關閉了應用,VDeleter將自動使用vkDestroyInstance將Instance銷燬。
以下是VDeleter的定義:
template <typename T>
class VDeleter {
public:
VDeleter() : VDeleter([](T, VkAllocationCallbacks*) {}) {}
VDeleter(std::function<void(T, VkAllocationCallbacks*)> deletef) {
this->deleter = [=](T obj) { deletef(obj, nullptr); };
}
VDeleter(const VDeleter<VkInstance>& instance, std::function<void(VkInstance, T, VkAllocationCallbacks*)> deletef) {
this->deleter = [&instance, deletef](T obj) { deletef(instance, obj, nullptr); };
}
VDeleter(const VDeleter<VkDevice>& device, std::function<void(VkDevice, T, VkAllocationCallbacks*)> deletef) {
this->deleter = [&device, deletef](T obj) { deletef(device, obj, nullptr); };
}
~VDeleter() {
cleanup();
}
T* operator &() {
cleanup();
return &object;
}
operator T() const {
return object;
}
private:
T object{VK_NULL_HANDLE};
std::function<void(T)> deleter;
void cleanup() {
if (object != VK_NULL_HANDLE) {
deleter(object);
}
object = VK_NULL_HANDLE;
}
};
後續的所有教程都將使用VDeleter來管理我們的對象。
Integrating GLFW
如果你只想離屏渲染(off-screen rendering),不需要創建窗口vulkan一樣可以很好的工作。但是,難道你不覺得在屏幕上顯示一些東西會更酷嗎?首先用如如下語句取代#include <vulkan/vulkan.h>
:
#define GLFW_INCLUDE_VULKAN
#include <GLFW/glfw3.h>
#define GLFW_INCLUDE_VULKAN
告訴glfw 在引入自己的頭文件時也要引入vulkan.h
。
在run
裏添加initWindow
來創建窗體:
void run() {
initWindow();
initVulkan();
mainLoop();
}
private:
void initWindow() {
}
初始化:
glfwInit() ;
GLFW最初是爲創建OPENGL 的 context設計的,爲了避免它創建OPENGL context,需要設置 :
glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
允許窗口改變大小會引起其他的問題,後續我們再討論,爲了操作簡單,這裏禁止改變窗口大小:
glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);
創建窗體:
const int WIDTH = 800;
const int HEIGHT = 600;
GLFWwindow* window = glfwCreateWindow(WIDTH, HEIGHT, "Vulkan", nullptr, nullptr);
第三個參數爲窗口(window)創建一個監視器,最後一個參數和OPENGL 相關。
顯示 ,直到遇到錯誤或關閉窗口:
while (!glfwWindowShouldClose(window)) {
glfwPollEvents();
}
爲了方便你對照和理解,這裏所有代碼:
#define GLFW_INCLUDE_VULKAN
#include <GLFW/glfw3.h>
#include <iostream>
#include <stdexcept>
#include <functional>
const int WIDTH = 800;
const int HEIGHT = 600;
template <typename T>
class VDeleter {
public:
VDeleter() : VDeleter([](T, VkAllocationCallbacks*) {}) {}
VDeleter(std::function<void(T, VkAllocationCallbacks*)> deletef) {
this->deleter = [=](T obj) { deletef(obj, nullptr); };
}
VDeleter(const VDeleter<VkInstance>& instance, std::function<void(VkInstance, T, VkAllocationCallbacks*)> deletef) {
this->deleter = [&instance, deletef](T obj) { deletef(instance, obj, nullptr); };
}
VDeleter(const VDeleter<VkDevice>& device, std::function<void(VkDevice, T, VkAllocationCallbacks*)> deletef) {
this->deleter = [&device, deletef](T obj) { deletef(device, obj, nullptr); };
}
~VDeleter() {
cleanup();
}
T* operator &() {
cleanup();
return &object;
}
operator T() const {
return object;
}
private:
T object{VK_NULL_HANDLE};
std::function<void(T)> deleter;
void cleanup() {
if (object != VK_NULL_HANDLE) {
deleter(object);
}
object = VK_NULL_HANDLE;
}
};
class HelloTriangleApplication {
public:
void run() {
initWindow();
initVulkan();
mainLoop();
}
private:
GLFWwindow* window;
void initWindow() {
glfwInit();
glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);
window = glfwCreateWindow(WIDTH, HEIGHT, "Vulkan", nullptr, nullptr);
}
void initVulkan() {
}
void mainLoop() {
while (!glfwWindowShouldClose(window)) {
glfwPollEvents();
}
}
};
int main() {
HelloTriangleApplication app;
try {
app.run();
} catch (const std::runtime_error& e) {
std::cerr << e.what() << std::endl;
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}