harmony 鸿蒙Vulkan Development

2023-10-30
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Vulkan Development

When to Use

Vulkan is a set of graphics APIs for 2D and 3D rendering. Creating a VkSurfaceKHR instance is a key step, since VkSurfaceKHR work with the OHNativeWindow module to implement buffer recycling.

A VkSurfaceKHR instance is obtained through an OHNativeWindow, which is obtained from the <XComponent>. Therefore, the OHNativeWindow module must be used together with the XComponent and NativeWindow modules.

Available APIs

API	Description
vkCreateSurfaceOHOS (VkInstance instance, const VkSurfaceCreateInfoOHOS* pCreateInfo, const VkAllocationCallbacks* pAllocator, VkSurfaceKHR* pSurface)	Creates a VkSurfaceKHR instance.

For details about the APIs, see Vulkan.

How to Develop

The following steps illustrate how to create a VkSurfaceKHR instance.

To use the extended APIs, define the macro VK_USE_PLATFORM_OHOS in the CMakeLists.txt file.

ADD_DEFINITIONS(-DVK_USE_PLATFORM_OHOS=1)

Adding Dynamic Link Libraries

Add the following libraries to CMakeLists.txt:

libace_ndk.z.so
libnative_window.so
libvulkan.so

Header File

#include <ace/xcomponent/native_interface_xcomponent.h>
#include <native_window/external_window.h>
#include <vulkan/vulkan.h>

Create a Vulkan instance.

   VkInstance instance = VK_NULL_HANDLE;
   
   VkApplicationInfo appInfo = {};
   appInfo.sType = VK_STRUCTURE_TYPE_APPLICATION_INFO;
   appInfo.pApplicationName = "vulkanExample";
   appInfo.pEngineName = "vulkanExample";
   appInfo.apiVersion = VK_API_VERSION_1_3;
   
   VkInstanceCreateInfo instanceCreateInfo = {};
   instanceCreateInfo.sType = VK_STRUCTURE_TYPE_INSTANCE_CREATE_INFO;
   instanceCreateInfo.pNext = NULL;
   instanceCreateInfo.pApplicationInfo = &appInfo;
   
   std::vector<const char *> instanceExtensions = {
       VK_KHR_SURFACE_EXTENSION_NAME,
       VK_OHOS_SURFACE_EXTENSION_NAME // Surface extension.
   };
   instanceCreateInfo.enabledExtensionCount = static_cast<uint32_t>(instanceExtensions.size());
   instanceCreateInfo.ppEnabledExtensionNames = instanceExtensions.data();
   
   vkCreateInstance(&instanceCreateInfo, nullptr, &instance);

Obtain an OHNativeWindow instance.

The OHNativeWindow instance is obtained from the <XComponent>. For details about how to use the <XComponent>, see XComponent and XComponent Development.

Add an <XComponent> to ets/pages/Index.ets.

  XComponent({
      id: 'xcomponentId',
      type: 'surface',
      libraryname: 'entry'
  })
  .margin({ bottom: 20 })
  .width(360)
  .height(360)

Obtain an OHNativeWindow instance from the <XComponent>.

  // Callback function of the \<XComponent> triggered when a surface is created.
  void OnSurfaceCreatedCB(OH_NativeXComponent *component, void *window) {
      // You can obtain an OHNativeWindow instance from the callback function.
      OHNativeWindow *nativeWindow = static_cast<OHNativeWindow *>(window);
  }


  static napi_value Init(napi_env env, napi_value exports) {
      napi_property_descriptor desc[] = {{"add", nullptr, Add, nullptr, nullptr, nullptr, napi_default, nullptr}};
      napi_define_properties(env, exports, sizeof(desc) / sizeof(desc[0]), desc);


      napi_value exportInstance = nullptr;
      OH_NativeXComponent *nativeXComponent = nullptr;
      // Obtain a native XComponent.
      napi_get_named_property(env, exports, OH_NATIVE_XCOMPONENT_OBJ, &exportInstance);
      napi_unwrap(env, exportInstance, reinterpret_cast<void **>(&nativeXComponent));
      // Obtain the XComponent ID.
      char idStr[OH_XCOMPONENT_ID_LEN_MAX + 1] = {};
      uint64_t idSize = OH_XCOMPONENT_ID_LEN_MAX + 1;
      OH_NativeXComponent_GetXComponentId(nativeXComponent, idStr, &idSize);


      // Declare an XComponent callback.
      OH_NativeXComponent_Callback callback;
      // Register the OnSurfaceCreated callback function.
      callback.OnSurfaceCreated = OnSurfaceCreatedCB;
      // Register the callback function for the native XComponent.
      OH_NativeXComponent_RegisterCallback(nativeXComponent, &callback);


      return exports;
  }

Create a VkSurfaceKHR instance.

   VkSurfaceKHR surface = VK_NULL_HANDLE;
   VkSurfaceCreateInfoOHOS surfaceCreateInfo = {};
   surfaceCreateInfo.sType = VK_STRUCTURE_TYPE_SURFACE_CREATE_INFO_OHOS;
   surfaceCreateInfo.window = nativeWindow; // nativeWindow is obtained from the OnSurfaceCreatedCB callback function in the previous step.
   int err = vkCreateSurfaceOHOS(instance, &surfaceCreateInfo, NULL, &surface);
   if (err != VK_SUCCESS) {
       // Creating the surface failed.
   }

For details about how to use Vulkan, visit the Vulkan official website.