当我们有了一个uniform buff之后，vulkan 还不知道这个信息，需要通过descriptor进行描述。
Descriptors and Descriptor Sets
Pipeline Layouts
A pipeline layout contains a list of descriptor set layouts. It also can contain a list of push constant ranges, which is an alternate way to pass constants to a shader and will not be covered here.
Shader Referencing of Descriptors
Create a Descriptor Set
Recall that the descriptor set that you defined is used to inform the GPU how the data contained in the uniform buffer is mapped to the shader program's uniform variables.