VK_EXT_legacy_dithering(3)

# VK_EXT_legacy_dithering(3) Manual Page

## Name

VK_EXT_legacy_dithering - device extension

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## Registered Extension Number

466

## Revision

1

## Ratification Status

Not ratified

## Extension and Version Dependencies

VK_KHR_get_physical_device_properties2

## API Interactions

- Interacts with VK_VERSION_1_3

- Interacts with VK_KHR_dynamic_rendering == Special Use

- OpenGL / ES support

## Contact

- Shahbaz Youssefi syoussefi

## Extension Proposal

VK_EXT_legacy_dithering

## Other Extension Metadata

Last Modified Date

  2022-03-31

Contributors

  - Shahbaz Youssefi, Google

  - Graeme Leese, Broadcom

  - Jan-Harald Fredriksen, Arm

## Description

This extension exposes a hardware feature used by some vendors to implement OpenGL’s dithering. The purpose of this extension is to support layering OpenGL over Vulkan, by allowing the layer to take advantage of the same hardware feature and provide equivalent dithering to OpenGL applications.

## New Structures

- Extending VkPhysicalDeviceFeatures2, VkDeviceCreateInfo:

  - VkPhysicalDeviceLegacyDitheringFeaturesEXT

## New Enum Constants

- `VK_EXT_LEGACY_DITHERING_EXTENSION_NAME`

- `VK_EXT_LEGACY_DITHERING_SPEC_VERSION`

- Extending VkStructureType:

  - `VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_LEGACY_DITHERING_FEATURES_EXT`

- Extending VkSubpassDescriptionFlagBits:

  - `VK_SUBPASS_DESCRIPTION_ENABLE_LEGACY_DITHERING_BIT_EXT`

If VK_KHR_dynamic_rendering is supported:

- Extending VkRenderingFlagBits:

  - `VK_RENDERING_ENABLE_LEGACY_DITHERING_BIT_EXT`

If Version 1.3 is supported:

- Extending VkRenderingFlagBits:

  - `VK_RENDERING_ENABLE_LEGACY_DITHERING_BIT_EXT`

## Version History

- Revision 1, 2022-03-31 (Shahbaz Youssefi)

  - Internal revisions

## Issues

1) In OpenGL, the dither state can change dynamically. Should this extension add a pipeline state for dither?

RESOLVED: No. Changing dither state is rarely, if ever, done during rendering. Every surveyed Android application either entirely disables dither, explicitly enables it, or uses the default state (which is enabled). Additionally, on some hardware dither can only be specified in a render pass granularity, so a change in dither state would necessarily need to cause a render pass break. This extension considers dynamic changes in OpenGL dither state a theoretical situation, and expects the layer to break the render pass in such a situation without any practical downsides.

## See Also

VkPhysicalDeviceLegacyDitheringFeaturesEXT

## 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.

## Copyright

Copyright 2014-2023 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0