EN中文
开发者社区 > 程序

vulakn教程--Drawing a Triangle--Presentation--Window surface

发表于2016-12-09
评论0 2.8k浏览

原文链接: Vulkan-tutorial

Window surface

因为Vulkan是平台(platform)无关的，它不能直接与平台窗体系统(window system)进行通信，为了连接Vulkan和窗体系统,使得被渲染后的结果显示到屏幕上，我们需要使用WSI扩展(Window System Integration extensions),在这个章节我们将使用VK_KHR_surface，它提供的VkSurfaceKHR 是对surface的一个抽象，使得我们能够将渲染后的结果放到VkSurfaceKHR上。还记得我们在之前使用GLFW创建的window吗，window将支持VkSurfaceKHR的创建。

VK_KHR_surface是一个Instance 级别的扩展，我们在创建Instance时已经通过glfwGetRequiredInstanceExtensions允许了这个扩展。

事实上，window surface的创建应该在Instance创建之后就应该完成，因为它会影响Physical Device的选取，之所以推迟到现在才讲，是因为window surface是关于渲染目标和显示的(render targets and presentation)一个比较大的话题，它会扰乱你对其他概念的理解。而且你要明白，如果你只是需要off-screen rendering，那么window surface对于Vulkan来说只是一个可选的扩展。

创建VkSurfaceKHR

声明：

?
1
VDeleter surface{instance, vkDestroySurfaceKHR};

如果我们在Windows上创建VkSurfaceKHR ，我们需要两个句柄: HWND 和HMODULE，并需要VK_KHR_win32_surface扩展，其实我们已经通过glfwGetRequiredInstanceExtensions允许了这个扩展，然后我们需要填充下面这个结构 :

?
1
2
3
4
VkWin32SurfaceCreateInfoKHR createInfo;
createInfo.sType = VK_STRUCTURE_TYPE_WIN32_SURFACE_CREATE_INFO_KHR;
createInfo.hwnd = glfwGetWin32Window(window);
createInfo.hinstance = GetModuleHandle(nullptr);

然后创建基于windows的surface:

?
1
2
3
4
5
6
auto CreateWin32SurfaceKHR = (PFN_vkCreateWin32SurfaceKHR) vkGetInstanceProcAddr(instance, "vkCreateWin32SurfaceKHR");
 
if (!CreateWin32SurfaceKHR || CreateWin32SurfaceKHR(instance, &createInfo,
        nullptr, &surface) != VK_SUCCESS) {
    throw std::runtime_error("failed to create window surface!");
}

但是我们不会这么犯傻，因为我们用的可是GLFW啊(GLFW是跨平台的)，我们没有必要去写一个基于特定平台的代码，而且这简直毫无道理。事实上，GLFW提供了glfwCreateWindowSurface方法，它自动为我们解决平台的差异性。

所以surface的创建应该是这样的 :

?
1
2
3
4
5
void createSurface() {
    if (glfwCreateWindowSurface(instance, window, nullptr, &surface) != VK_SUCCESS) {
        throw std::runtime_error("failed to create window surface!");
    }
}

就是这么简单优雅！

确定显卡支持WSI(请求显示支持)

尽管Vulkan的实现可能支持WSI ，但并不代表你平台上的所有显卡也支持，它是指Physical Device 中存在一种将images提交到Surface上的命令队列。因此我们需要扩展下面这个函数:

?
1
2
3
4
5
bool isDeviceSuitable(VkPhysicalDevice device) {
    QueueFamilyIndices indices = findQueueFamilies(device);
 
    return indices.isComplete();
}

注：这个函数其实并未修改。

我们修改isDeviceSuitable(…)的目的是确保能够将渲染好的图片(images)提交(present)到我们所创建的surface上。又因为显示(presentation)是基于队列的，那么问题就转换为:从显卡里寻找一种具有将渲染结果提交(presenting)到surface上的命令的队列(queue family)。

绘画命令和显示命令可能不重叠在一种队列，所以我们需要修改一下结构:

?
1
2
3
4
5
6
7
8
struct QueueFamilyIndices {
    int graphicsFamily = -1;
    int presentFamily = -1;
 
    bool isComplete() {
        return graphicsFamily >= 0 && presentFamily >= 0;
    }
};

接下来，为了检测队列是否支持将渲染结果提交(presenting)到surface上，我们使用:

?
1
2
3
4
5
VkResult vkGetPhysicalDeviceSurfaceSupportKHR(
    VkPhysicalDevice physicalDevice,
    uint32_t queueFamilyIndex,
    VkSurfaceKHR surface,
    VkBool32* pSupported);

这里不做解释，参数已经见名知意了。

联合以上思想，findQueueFamilies(…) 将变成下面这个样子:

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
QueueFamilyIndices findQueueFamilies(VkPhysicalDevice device) {
    QueueFamilyIndices indices;
 
    uint32_t queueFamilyCount = 0;
    vkGetPhysicalDeviceQueueFamilyProperties(device, &queueFamilyCount, nullptr);
 
    std::vector queueFamilies(queueFamilyCount);
    vkGetPhysicalDeviceQueueFamilyProperties(device, &queueFamilyCount, queueFamilies.data());
 
    int i = 0;
    for (const auto& queueFamily : queueFamilies) {
        if (queueFamily.queueCount > 0 && queueFamily.queueFlags & VK_QUEUE_GRAPHICS_BIT) {
            indices.graphicsFamily = i;
        }
        VkBool32 presentSupport = false;
        vkGetPhysicalDeviceSurfaceSupportKHR(device, i, surface, &presentSupport);
 
        if (queueFamily.queueCount > 0 && presentSupport) {
            indices.presentFamily = i;
        }
 
        if (indices.isComplete()) {
            break;
        }
 
        i++;
    }
    return indices;
}

注意，我们在创建Logical Device时已经创建了一个队列用于支持图形处理的graphicsQueue，现在我们变更了需求，又多了一个用于将渲染结果提交(presenting)到surface上的队列。 那么，Logical Device的创建过程也需要改变。

获取presentQueue:

VkQueue presentQueue; //声明
?
1
VkQueue presentQueue;  //声明

createLogicalDevice(…)的改变部分:

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
void createLogicalDevice() {
        ...
        std::vector queueCreateInfos;
        std::set<int> uniqueQueueFamilies = {indices.graphicsFamily, indices.presentFamily};
 
        float queuePriority = 1.0f;
        for (int 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);
        }
        ...
        VkDeviceCreateInfo createInfo = {};
        createInfo.sType = VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO;
 
        createInfo.pQueueCreateInfos = queueCreateInfos.data();
        createInfo.queueCreateInfoCount = (uint32_t) queueCreateInfos.size();
        createInfo.pEnabledFeatures = &deviceFeatures;
        createInfo.enabledExtensionCount = 0;     
        ...
        ...
        vkGetDeviceQueue(device, indices.presentFamily, 0, &presentQueue);
    }int>

如果presentFamily和graphicsFamily是同一种队列，presentQueue和graphicsQueue将指向同一个对象。

注：在我的平台上，它们两个是一个队列。

源码：

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
#define GLFW_INCLUDE_VULKAN
#include
 
#include
#include
#include
#include
#include
#include
 
const int WIDTH = 800;
const int HEIGHT = 600;
 
const std::vector<const char*=""> validationLayers = {
    "VK_LAYER_LUNARG_standard_validation"
};
 
#ifdef NDEBUG
const bool enableValidationLayers = false;
#else
const bool enableValidationLayers = true;
#endif
 
VkResult CreateDebugReportCallbackEXT(VkInstance instance, const VkDebugReportCallbackCreateInfoEXT* pCreateInfo, const VkAllocationCallbacks* pAllocator, VkDebugReportCallbackEXT* pCallback) {
    auto func = (PFN_vkCreateDebugReportCallbackEXT) vkGetInstanceProcAddr(instance, "vkCreateDebugReportCallbackEXT");
    if (func != nullptr) {
        return func(instance, pCreateInfo, pAllocator, pCallback);
    } else {
        return VK_ERROR_EXTENSION_NOT_PRESENT;
    }
}
 
void DestroyDebugReportCallbackEXT(VkInstance instance, VkDebugReportCallbackEXT callback, const VkAllocationCallbacks* pAllocator) {
    auto func = (PFN_vkDestroyDebugReportCallbackEXT) vkGetInstanceProcAddr(instance, "vkDestroyDebugReportCallbackEXT");
    if (func != nullptr) {
        func(instance, callback, pAllocator);
    }
}
 
template "">
class VDeleter {
public:
    VDeleter() : VDeleter([](T, VkAllocationCallbacks*) {}) {}
 
    VDeleter(std::function<void(t, vkallocationcallbacks*)=""> deletef) {
        this->deleter = [=](T obj) { deletef(obj, nullptr); };
    }
 
    VDeleter(const VDeleter& instance, std::function<void(vkinstance, t,="" vkallocationcallbacks*)=""> deletef) {
        this->deleter = [&instance, deletef](T obj) { deletef(instance, obj, nullptr); };
    }
 
    VDeleter(const VDeleter& 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;
    }
};
 
struct QueueFamilyIndices {
    int graphicsFamily = -1;
    int presentFamily = -1;
 
    bool isComplete() {
        return graphicsFamily >= 0 && presentFamily >= 0;
    }
};
 
class HelloTriangleApplication {
public:
    void run() {
        initWindow();
        initVulkan();
        mainLoop();
    }
 
private:
    GLFWwindow* window;
 
    VDeleter instance{vkDestroyInstance};
    VDeleter callback{instance, DestroyDebugReportCallbackEXT};
    VDeleter surface{instance, vkDestroySurfaceKHR};
 
    VkPhysicalDevice physicalDevice = VK_NULL_HANDLE;
    VDeleter device{vkDestroyDevice};
 
    VkQueue graphicsQueue;
    VkQueue presentQueue;
 
    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();
        setupDebugCallback();
        createSurface();
        pickPhysicalDevice();
        createLogicalDevice();
    }
 
    void mainLoop() {
        while (!glfwWindowShouldClose(window)) {
            glfwPollEvents();
        }
    }
 
    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;
 
        auto extensions = getRequiredExtensions();
        createInfo.enabledExtensionCount = extensions.size();
        createInfo.ppEnabledExtensionNames = extensions.data();
 
        if (enableValidationLayers) {
            createInfo.enabledLayerCount = validationLayers.size();
            createInfo.ppEnabledLayerNames = validationLayers.data();
        } else {
            createInfo.enabledLayerCount = 0;
        }
 
        if (vkCreateInstance(&createInfo, nullptr, &instance) != VK_SUCCESS) {
            throw std::runtime_error("failed to create instance!");
        }
    }
 
    void setupDebugCallback() {
        if (!enableValidationLayers) return;
 
        VkDebugReportCallbackCreateInfoEXT createInfo = {};
        createInfo.sType = VK_STRUCTURE_TYPE_DEBUG_REPORT_CALLBACK_CREATE_INFO_EXT;
        createInfo.flags = VK_DEBUG_REPORT_ERROR_BIT_EXT | VK_DEBUG_REPORT_WARNING_BIT_EXT;
        createInfo.pfnCallback = debugCallback;
 
        if (CreateDebugReportCallbackEXT(instance, &createInfo, nullptr, &callback) != VK_SUCCESS) {
            throw std::runtime_error("failed to set up debug callback!");
        }
    }
 
    void createSurface() {
        if (glfwCreateWindowSurface(instance, window, nullptr, &surface) != VK_SUCCESS) {
            throw std::runtime_error("failed to create window surface!");
        }
    }
 
    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 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!");
        }
    }
 
    void createLogicalDevice() {
        QueueFamilyIndices indices = findQueueFamilies(physicalDevice);
 
        std::vector queueCreateInfos;
        std::set<int> uniqueQueueFamilies = {indices.graphicsFamily, indices.presentFamily};
 
        float queuePriority = 1.0f;
        for (int 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 = {};
 
        VkDeviceCreateInfo createInfo = {};
        createInfo.sType = VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO;
 
        createInfo.pQueueCreateInfos = queueCreateInfos.data();
        createInfo.queueCreateInfoCount = (uint32_t) queueCreateInfos.size();
 
        createInfo.pEnabledFeatures = &deviceFeatures;
 
        createInfo.enabledExtensionCount = 0;
 
        if (enableValidationLayers) {
            createInfo.enabledLayerCount = validationLayers.size();
            createInfo.ppEnabledLayerNames = validationLayers.data();
        } else {
            createInfo.enabledLayerCount = 0;
        }
 
        if (vkCreateDevice(physicalDevice, &createInfo, nullptr, &device) != VK_SUCCESS) {
            throw std::runtime_error("failed to create logical device!");
        }
 
        vkGetDeviceQueue(device, indices.graphicsFamily, 0, &graphicsQueue);
        vkGetDeviceQueue(device, indices.presentFamily, 0, &presentQueue);
    }
 
    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 queueFamilies(queueFamilyCount);
        vkGetPhysicalDeviceQueueFamilyProperties(device, &queueFamilyCount, queueFamilies.data());
 
        int i = 0;
        for (const auto& queueFamily : queueFamilies) {
            if (queueFamily.queueCount > 0 && queueFamily.queueFlags & VK_QUEUE_GRAPHICS_BIT) {
                indices.graphicsFamily = i;
            }
 
            VkBool32 presentSupport = false;
            vkGetPhysicalDeviceSurfaceSupportKHR(device, i, surface, &presentSupport);
 
            if (queueFamily.queueCount > 0 && presentSupport) {
                indices.presentFamily = i;
            }
 
            if (indices.isComplete()) {
                break;
            }
 
            i++;
        }
 
        return indices;
    }
 
    std::vector<const char*=""> getRequiredExtensions() {
        std::vector<const char*=""> extensions;
 
        unsigned int glfwExtensionCount = 0;
        const char** glfwExtensions;
        glfwExtensions = glfwGetRequiredInstanceExtensions(&glfwExtensionCount);
 
        for (unsigned int i = 0; i < glfwExtensionCount; i++) {
            extensions.push_back(glfwExtensions[i]);
        }
 
        if (enableValidationLayers) {
            extensions.push_back(VK_EXT_DEBUG_REPORT_EXTENSION_NAME);
        }
 
        return extensions;
    }
 
    bool checkValidationLayerSupport() {
        uint32_t layerCount;
        vkEnumerateInstanceLayerProperties(&layerCount, nullptr);
 
        std::vector 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;
    }
 
    static VKAPI_ATTR VkBool32 VKAPI_CALL debugCallback(VkDebugReportFlagsEXT flags, VkDebugReportObjectTypeEXT objType, uint64_t obj, size_t location, int32_t code, const char* layerPrefix, const char* msg, void* userData) {
        std::cerr << "validation layer: " << msg << std::endl;
 
        return VK_FALSE;
    }
};
 
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;
}const>const>int>void(t)>void(vkdevice,>void(vkinstance,>void(t,>const>set>

如社区发表内容存在侵权行为，您可以点击这里查看侵权投诉指引

标签：

游戏开发渲染游戏视觉VulkanGPUTPS