This step modifies fragment coverage values based on the values in the pSampleMask array member of VkPipelineMultisampleStateCreateInfo, as described previously in section Section 9.2, “Graphics Pipelines”.
pSampleMask contains a bitmask of static coverage information that is ANDed with the coverage information generated during rasterization. Bits that are zero disable coverage for the corresponding sample. Bit B of mask word M corresponds to sample $32 \times M + B$ . The array is sized to a length of $\lceil{rasterizationSamples / 32}\rceil$ words. If pSampleMask is NULL, it is treated as if the mask has all bits enabled, i.e. no coverage is removed from fragments.