VK_QCOM_fragment_density_map_offset(3) Manual Page

// Create fragment density map
VkImageCreateInfo imageCreateInfo =
{
   VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO,
   nullptr,
   VK_IMAGE_CREATE_FRAGMENT_DENSITY_MAP_OFFSET_BIT_QCOM,
   VK_IMAGE_TYPE_2D,       // Must be 2D
   VK_FORMAT_R8G8_UNORM,   // Must have VK_FORMAT_FEATURE_FRAGMENT_DENSITY_MAP_BIT_EXT
   {64, 64, 1},            // extent
   1,                      // mipLevels
   2,                      // arrayLayers; 1 for each multiview view
   VK_SAMPLE_COUNT_1_BIT,  // Must be 1x MSAA
   tiling,
   VK_IMAGE_USAGE_FRAGMENT_DENSITY_MAP_BIT_EXT,
   // ...
};

vkCreateImage(device, &imageCreateInfo, nullptr, &fdmImage);

// Start renderpass with fbo that has fdmImage as fragmentDensityMapAttachment
// All other attachments must have been created with
// VK_IMAGE_CREATE_FRAGMENT_DENSITY_MAP_OFFSET_BIT_QCOM
// FBO has dimensions 1024x1024 in this example
vkCmdBeginRenderPass2(commandBuffer, &renderPassBeginInfo, pSubpassBeginInfo);

// ...

// Shift fragment density map image by offset to put fovea in center of vision
/*
   If minFragmentDensityTexelSize is 32x32, then offsets can be at most
   1024x1024 for this example before density value access is clamped to edge of map

   This is because the region of each fdmImage texel is

     texelSize = max(framebuffer / fdmImage, minFragmentDensityTexelSize) = 32x32

   and the fdmImage covers a total framebuffer region of

     fdmImageRegion = fdmImage * texelSize = 2048x2048

   This means that the framebuffer (1024x1024) can be shifted up to 1024x1024
   before the density values are clamped to edge of map
*/
VkSubpassFragmentDensityMapOffsetEndInfoQCOM offsetInfo =
{
   VK_STRUCTURE_TYPE_SUBPASS_FRAGMENT_DENSITY_MAP_OFFSET_END_INFO_QCOM,
   2,             // fragmentDensityOffsetCount; 1 for each layer/multiview view
   offsets,       // offsets are aligned to fragmentDensityOffsetGranularity
};

subpassEndInfo.pNext = &offsetInfo;

// Only offsets given to the last subpass are used for the whole render pass
// Offsets given in other subpasses are ignored
vkCmdEndRenderPass2(VkCommandBuffer commandBuffer, &subpassEndInfo);