Name

VK_EXT_shader_uniform_buffer_unsized_array - device extension

VK_EXT_shader_uniform_buffer_unsized_array

Name String

VK_EXT_shader_uniform_buffer_unsized_array

Extension Type

Device extension

Registered Extension Number

643

Revision

1

Ratification Status

Ratified

Extension and Version Dependencies

VK_KHR_get_physical_device_properties2 or Vulkan Version 1.1

Contact

• Piers Daniell @pdaniell-nv%0A*Here describe the issue or question you have about the VK_EXT_shader_uniform_buffer_unsized_array extension*

Extension Proposal

VK_EXT_shader_uniform_buffer_unsized_array

Other Extension Metadata

Last Modified Date

2025-05-28

Contributors

• Pat Brown, NVIDIA
• Jeff Bolz, NVIDIA
• Pranjal Dubey, NVIDIA

Description

This extension allows the last member of a uniform buffer block to be declared as an unsized array. This capability enables applications to create flexible buffer layouts where the array size can vary based on runtime requirements.

When the last member of a uniform buffer block is declared as an unsized array, the effective array size is inferred at runtime from the size of the buffer object backing the uniform buffer block. Such unsized arrays can be indexed with general integer expressions, but may not be passed as arguments to functions or indexed with negative constant expressions.

This extension leverages existing SPIR-V capabilities, allowing use of OpTypeRuntimeArray as the last member of a uniform buffer block structure while prohibiting OpArrayLength.

Applications needing to know array sizes at runtime should calculate the length and pass it to shaders via a separate uniform. This calculation can be performed using the formula: max((buffer_object_size - offset_of_array) / stride_of_array, 0), where buffer_object_size is the size of the bound buffer, offset_of_array is the byte offset of the array in the block, and stride_of_array is the byte stride between consecutive array elements.

Uniform buffers have traditionally required explicit sizes for all arrays which limits flexibility. With this extension, developers can create a single shader that adapts to different data set sizes at runtime by binding differently sized buffers.

New Structures

• Extending PhysicalDeviceFeatures2, DeviceCreateInfo:

  • PhysicalDeviceShaderUniformBufferUnsizedArrayFeaturesEXT

New Enum Constants

• EXT_SHADER_UNIFORM_BUFFER_UNSIZED_ARRAY_EXTENSION_NAME

• EXT_SHADER_UNIFORM_BUFFER_UNSIZED_ARRAY_SPEC_VERSION

• Extending StructureType:

  • STRUCTURE_TYPE_PHYSICAL_DEVICE_SHADER_UNIFORM_BUFFER_UNSIZED_ARRAY_FEATURES_EXT

Version History

• Revision 1, 2025-05-28 (Pranjal Dubey)

  • Initial draft

See Also

No cross-references are available

Document Notes

For more information, see the Vulkan Specification.

This page is a generated document. Fixes and changes should be made to the generator scripts, not directly.