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* Update release number to 98.
Public Issues:
* Fix missing markup in flink:vkDestroyPipelineLayout valid usage
statement (pull request 882).
* Add missing contributors for `<<VK_EXT_buffer_device_address>>` (public
pull request 891).
Internal Issues:
* Detect nested bullet points in valid usage blocks and warn about them
during VUID assignment (internal issue 1382).
* Update the style guide to document the process for reserving new bits in
bitmask types (internal issue 1411).
* Clarify for slink:VkApplicationInfo::pname:apiVersion and in the
<<fundamentals-validusage-versions, Valid Usage for Newer Core
Versions>> section when it is valid for an application to use a certain
version of Vulkan API functionality (for an instance and for a
device/physical device); and when the validation layers must generate an
error (internal issue 1412).
* Add optional <<memory-model-availability-visibility, transitive
availability/visibility operations to the memory model, including a new
pname:vulkanMemoryModelAvailabilityVisibilityChains feature for
slink:VkPhysicalDeviceVulkanMemoryModelFeaturesKHR (internal issue
1460).
* Add the code:StorageBuffer storage class to those in the
<<interfaces-resources-descset, Descriptor Set Interface>> (internal
issue 1480).
* Add missing `returnedonly` tags for a number of returned extension
structures that can be passed in pname:pNext chains (internal issue
1515).
* Clean up and rearrange some spec language for
slink:VkRenderPassCreateInfo and slink:VkAttachmentReference.txt
(internal issue 1522).
* Correctly round the code:OpVectorTimesScalar and
code:OpMatrixTimesScalar SPIR-V operations in the <<Precision of core
SPIR-V Instructions>> table (internal merge request 2996).
* Work around cases in flink:vkCmdBeginTransformFeedbackEXT,
flink:vkCmdEndTransformFeedbackEXT, and
slink:VkPipelineCoverageModulationStateCreateInfoNV where an array
parameter is `optional` but the length is not in `vk.xml`. This is an
interim fix using `noautovalidity` + handcoded VU replacing those that
should be autogenerated (internal issue 2944 and
https://github.com/KhronosGroup/Vulkan-ValidationLayers/issues/480).
* Remove redundant capability validation of the code:float16 and code:int8
SPIR-V capabilities from the <<spirvenv-capabilities, Capabilities>>
section, since they are already covered in the preceding table.
* Update check_spec_links script, including validation for reference page
open blocks. Fix errors identified by the script.
115 lines
3.5 KiB
Plaintext
115 lines
3.5 KiB
Plaintext
// Copyright (c) 2018-2019 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 ename:VK_FORMAT_R8G8B8A8_UNORM
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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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