创建mvp ubo(uniform buffer object)

创建过程：

1. 创建一个uniform buffer
2. 查找buffer memory requirements
3. 分配、绑定buffer memory
4. map buffer memory
5. 拷贝mvp data to buffer memory
6. unmap buffer memory

示例代码：

glm::mat4 projection = glm::perspective(glm::radians(45.0f), 1.0f, 0.1f, 100.0f);
glm::mat4 view = glm::lookAt(glm::vec3(-5, 3, -10),  // 相机在世界坐标系中的位置glm::vec3(0, 0, 0),     // 看向的目标位置glm::vec3(0, -1, 0)     // 相机up方向向量);
glm::mat4 model = glm::mat4(1.0f);
glm::mat4 clip = glm::mat4(1.0f, 0.0f, 0.0f, 0.0f,0.0f,-1.0f, 0.0f, 0.0f,0.0f, 0.0f, 0.5f, 0.0f,0.0f, 0.0f, 0.5f, 1.0f);
glm::mat4 mvp = clip * projection * view * model;VkBuffer ubo;
VkBufferCreateInfo buf_info = {};
buf_info.sType = VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO;
buf_info.pNext = NULL;
buf_info.usage = VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT;
buf_info.size = sizeof(mvp);
buf_info.queueFamilyIndexCount = 0;
buf_info.pQueueFamilyIndices = NULL;
buf_info.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
buf_info.flags = 0;
vkCreateBuffer(device, &buf_info, NULL, &ubo);VkMemoryRequirements mem_reqs;
vkGetBufferMemoryRequirements(device, ubo, &mem_reqs);VkDeviceMemory mem;
VkMemoryAllocateInfo alloc_info = {};
alloc_info.sType = VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO;
alloc_info.pNext = NULL;
alloc_info.memoryTypeIndex = 0;
alloc_info.allocationSize = mem_reqs.size;
vkAllocateMemory(device, &alloc_info, NULL, &mem);vkBindBufferMemory(device, ubo, mem, 0);uint8_t *pData;
vkMapMemory(device, mem, 0, mem_reqs.size, 0, (void **)&pData);memcpy(pData, &mvp, sizeof(mvp));vkUnmapMemory(device, mem);