vkGetDescriptorSetLayoutBindingOffsetEXT

To get the offset of a binding within a descriptor set layout in memory, call:

void vkGetDescriptorSetLayoutBindingOffsetEXT(
    VkDevice device,
    VkDescriptorSetLayout layout,
    uint32_t binding,
    VkDeviceSize* pOffset);

• device is the logical device that gets the offset.
• layout is the descriptor set layout being queried.
• binding is the binding number being queried.
• pOffset is a pointer to VkDeviceSize where the byte offset of the binding will be written.

Each binding in a descriptor set layout is assigned an offset in memory by the implementation. When a shader accesses a resource with that binding, it will access the bound descriptor buffer from that offset to look for its descriptor. This command provides an application with that offset, so that descriptors can be placed in the correct locations. The precise location accessed by a shader for a given descriptor is as follows:

• location = bufferAddress + setOffset + descriptorOffset + (arrayElement × descriptorSize)

where bufferAddress and setOffset are the base address and offset for the identified descriptor set as specified by vkCmdBindDescriptorBuffersEXT and vkCmdSetDescriptorBufferOffsetsEXT, descriptorOffset is the offset for the binding returned by this command, arrayElement is the index into the array specified in the shader, and descriptorSize is the size of the relevant descriptor as obtained from VkPhysicalDeviceDescriptorBufferPropertiesEXT. Applications are responsible for placing valid descriptors at the expected location in order for a shader to access it. The overall offset added to bufferAddress to calculate location must be less than VkPhysicalDeviceDescriptorBufferPropertiesEXT::maxSamplerDescriptorBufferRange for samplers and VkPhysicalDeviceDescriptorBufferPropertiesEXT::maxResourceDescriptorBufferRange for resources.

If any binding in layout is VK_DESCRIPTOR_BINDING_VARIABLE_DESCRIPTOR_COUNT_BIT, that binding must have the largest offset of any binding.

A descriptor binding with type VK_DESCRIPTOR_TYPE_MUTABLE_VALVEcan be used. Any potential types in VkMutableDescriptorTypeCreateInfoVALVE::pDescriptorTypes for binding share the same offset. If the size of the mutable descriptor is larger than the size of a concrete descriptor type being accessed, the padding area is ignored by the implementation.