CODEWITHSUNDEEP
vulkan
Andrew Tomazos
Andrew Tomazos

Reputation: 68618

What does noautovalidity mean in Vulkan API schema (vk.xml)?

What does noautovalidity mean on a struct member definition in the Vulkan API schema (vk.xml)?

registry.rnc says tag stating that no automatic validity language should be generated

The Vulkan registry spec says: prevents automatic validity language being generated for the tagged item. Only suppresses item-specific validity - parenting issues etc. are still captured. It must also be used for structures that have no implicit validity when such structure has explicit validity.

What is automatic validity language?

What is an example of something that has noautovalidity, and of that example, what was the item-specific validity that is suppressed? and why was it decided to be suppressed?

Upvotes: 0

Views: 248

Answers (1)

krOoze
krOoze

Reputation: 13246

Consult the XML schema doc.

noautovalidity means most Valid Usage (Implicit) entries will not be generated for a given parameter or structure member.

It may mean Implicit Validity rules do not apply to the given item, although many times very similar Explicit VU is given in its place.

Examples:

VkWriteDescriptorSet::pImageInfo has noautovalidity because it shares descriptorCount. It prevents generating something like "pImageInfo has to be an array of descriptorCount elements". Instead Explicit VU is given, e.g.: "If descriptorType is *_IMAGE, then pImageInfo has to be an array of descriptorCount elements`.

VkComputePipelineCreateInfo::basePipelineHandle is noautovalidity because the API allows the parameter to be ignored if flags does not contain VK_PIPELINE_CREATE_DERIVATIVE_BIT. Without the attribute the spec would insist the handle has to be a valid VkPipeline (or additionally allowed to be VK_NULL_HANDLE if optional).

Corner case example:

VkViewport::x is noautovalidity. It does not seemingly need noautovalidity, but in this case it signifies that although the struct has no Implicit Validity, some Explicit Validity may be present in the spec.

Upvotes: 4

Related Questions