vkGetMicromapBuildSizesEXT

To get the build sizes for a micromap, call:

void vkGetMicromapBuildSizesEXT(
    VkDevice                                            device,
    VkAccelerationStructureBuildTypeKHR                 buildType,
    const VkMicromapBuildInfoEXT*  pBuildInfo,
    VkMicromapBuildSizesInfoEXT*           pSizeInfo);

pub fn get_micromap_build_sizes_ext(
    device: vk::Device,
    build_type: vk::AccelerationStructureBuildTypeKHR,
    p_build_info: *const vk::MicromapBuildInfoEXT,
    p_size_info: *mut vk::MicromapBuildSizesInfoEXT,
);

• device is the logical device that will be used for creating the micromap.
• buildType defines whether host or device operations (or both) are being queried for.
• pBuildInfo is a pointer to a VkMicromapBuildInfoEXT structure describing parameters of a build operation.
• pSizeInfo is a pointer to a VkMicromapBuildSizesInfoEXT structure which returns the size required for a micromap and the sizes required for the scratch buffers, given the build parameters. The size requirements for a scratch buffer may be zero.

The dstMicromap and mode members of pBuildInfo are ignored. Any VkDeviceOrHostAddressKHR members of pBuildInfo are ignored by this command.

A micromap created with the micromapSize returned by this command supports any build with a VkMicromapBuildInfoEXT structure subject to the following properties:

• The build command is a host build command, and buildType is VK_ACCELERATION_STRUCTURE_BUILD_TYPE_HOST_KHR or VK_ACCELERATION_STRUCTURE_BUILD_TYPE_HOST_OR_DEVICE_KHR
• The build command is a device build command, and buildType is VK_ACCELERATION_STRUCTURE_BUILD_TYPE_DEVICE_KHR or VK_ACCELERATION_STRUCTURE_BUILD_TYPE_HOST_OR_DEVICE_KHR
• For VkMicromapBuildInfoEXT:
  • Its type, and flags members are equal to pBuildInfo→type and pBuildInfo→flags, respectively.
  • The sum of usage information in either pUsageCounts or ppUsageCounts is equal to the sum of usage information in either pBuildInfo→pUsageCounts or pBuildInfo→ppUsageCounts.

Similarly, the buildScratchSize value will support any build command specifying the VK_BUILD_MICROMAP_MODE_BUILD_EXT mode under the above conditions.