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* Update release number to 92.
Public Issues:
* Move and modify valid usage statements dealing with pname:aspectMask in
flink:vkCmdClearColorImage, flink:vkCmdClearDepthStencilImage, and
slink:VkClearAttachment, so they are in places where all necessary
information is available (public issue 529).
* Fix math markup in <<textures-texel-anisotropic-filtering, Texel
Anisotropic Filtering>> (public pull request 840).
* Fix misspellings (public pull request 845).
Internal Issues:
* Add installation instructions and a Makefile "`chunked`" target for
chunked HTML generation (internal issue 1352).
* Fix pipeline mesh diagram style; also fix a minor bug in the classic
pipeline diagram where vertex/index buffers wrongly fed into the vertex
shader (internal issue 1436).
* Make asciidoctor ERROR output raise an error, and don't suppress
executed command output from CI make invocation (internal issue 1454).
* Minor typo fixes and clarifications for `VK_NV_raytracing`.
* Cleanup extension-specific properties
** Remove duplicated documentation for pname:maxDiscardRectangles,
pname:pointClippingBehavior, and pname:maxVertexAttribDivisor (they
shouldn't be documented with the other members of
slink:VkPhysicalDeviceLimits at all).
** Remove duplicate anchor for pname:maxVertexAttribDivisor
** Consistently document stext:VkPhysicalDevice<Extension>PropertiesKHR
*** Always document pname:sType/pname:pNext (was inconsistent before)
*** Always mention chaining to slink:VkPhysicalDeviceProperties2 (and not
as slink:VkPhysicalDeviceProperties2KHR)
*** Always include Valid Usage statements last
* Update Makefile 'checklinks' target and associated scripts, and fix
markup problems identified by checkLinks.py, so that we can rely on the
checklinks script as part of Gitlab CI.
114 lines
3.5 KiB
Plaintext
114 lines
3.5 KiB
Plaintext
// Copyright (c) 2018 Khronos Group. This work is licensed under a
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// Creative Commons Attribution 4.0 International License; see
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// http://creativecommons.org/licenses/by/4.0/
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include::meta/VK_EXT_astc_decode_mode.txt[]
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Last Modified Date::
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2018-08-07
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Contributors::
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- Jan-Harald Fredriksen, Arm
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The existing specification requires that low dynamic range (LDR) ASTC
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textures are decompressed to FP16 values per component.
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In many cases, decompressing LDR textures to a lower precision intermediate
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result gives acceptable image quality.
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Source material for LDR textures is typically authored as 8-bit UNORM
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values, so decoding to FP16 values adds little value.
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On the other hand, reducing precision of the decoded result reduces the size
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of the decompressed data, potentially improving texture cache performance
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and saving power.
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The goal of this extension is to enable this efficiency gain on existing
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ASTC texture data.
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This is achieved by giving the application the ability to select the
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intermediate decoding precision.
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Three decoding options are provided:
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* Decode to ename:VK_FORMAT_R16G16B16A16_SFLOAT precision: This is the
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default, and matches the required behavior in the core API.
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* Decode to ename:VK_FORMAT_R8G8B8A8_UNORM precision: This is provided as
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an option in LDR mode.
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* Decode to ename:VK_FORMAT_E5B9G9R9_UFLOAT_PACK32 precision: This is
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provided as an option in both LDR and HDR mode.
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In this mode, negative values cannot be represented and are clamped to
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zero.
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The alpha component is ignored, and the results are as if alpha was 1.0.
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This decode mode is optional and support can be queried via the physical
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device properties.
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=== New Enum Constants
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* Extending elink:VkStructureType:
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** ename:VK_STRUCTURE_TYPE_IMAGE_VIEW_ASTC_DECODE_MODE_EXT
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** ename:VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_ASTC_DECODE_FEATURES_EXT
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=== New Enums
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None.
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=== New Structures
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* slink:VkImageViewASTCDecodeModeEXT
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* slink:VkPhysicalDeviceASTCDecodeFeaturesEXT
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=== New Functions
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None.
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=== Issues
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1) Are implementations allowed to decode at a higher precision than what is
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requested?
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RESOLUTION: No.
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If we allow this, then this extension could be exposed on all
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implementations that support ASTC.
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But developers would have no way of knowing what precision was actually
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used, and thus whether the image quality is sufficient at reduced
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precision.
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2) Should the decode mode be image view state and/or sampler state?
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RESOLUTION: Image view state only.
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Some implementations treat the different decode modes as different
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texture formats.
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=== Example
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Create an image view that decodes to VK_FORMAT_R8G8B8A8_UNORM precision:
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[source,c++]
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----------------------------------------
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VkImageViewASTCDecodeModeEXT decodeMode =
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{
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VK_STRUCTURE_TYPE_IMAGE_VIEW_ASTC_DECODE_MODE_EXT, // sType
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NULL, // pNext
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VK_FORMAT_R8G8B8A8_UNORM // decode mode
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};
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VkImageViewCreateInfo createInfo =
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{
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VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO, // sType
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&decodeMode, // pNext
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// flags, image, viewType set to application-desired values
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VK_FORMAT_ASTC_8x8_UNORM_BLOCK, // format
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// components, subresourceRange set to application-desired values
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};
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VkImageView imageView;
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VkResult result = vkCreateImageView(
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device,
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&createInfo,
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NULL,
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&imageView);
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----------------------------------------
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=== Version History
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* Revision 1, 2018-08-07 (Jan-Harald Fredriksen)
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- Initial revision
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