Safe Haskell | Safe-Inferred |
---|---|
Language | Haskell2010 |
Name
VK_EXT_astc_decode_mode - device extension
VK_EXT_astc_decode_mode
- Name String
VK_EXT_astc_decode_mode
- Extension Type
- Device extension
- Registered Extension Number
- 68
- Revision
- 1
- Ratification Status
- Not ratified
- Extension and Version Dependencies
- VK_KHR_get_physical_device_properties2 or Version 1.1
- Contact
Other Extension Metadata
- Last Modified Date
- 2018-08-07
- Contributors
- Jan-Harald Fredriksen, Arm
Description
The existing specification requires that low dynamic range (LDR) ASTC textures are decompressed to FP16 values per component. In many cases, decompressing LDR textures to a lower precision intermediate result gives acceptable image quality. Source material for LDR textures is typically authored as 8-bit UNORM values, so decoding to FP16 values adds little value. On the other hand, reducing precision of the decoded result reduces the size of the decompressed data, potentially improving texture cache performance and saving power.
The goal of this extension is to enable this efficiency gain on existing ASTC texture data. This is achieved by giving the application the ability to select the intermediate decoding precision.
Three decoding options are provided:
- Decode to
FORMAT_R16G16B16A16_SFLOAT
precision: This is the default, and matches the required behavior in the core API. - Decode to
FORMAT_R8G8B8A8_UNORM
precision: This is provided as an option in LDR mode. - Decode to
FORMAT_E5B9G9R9_UFLOAT_PACK32
precision: This is provided as an option in both LDR and HDR mode. In this mode, negative values cannot be represented and are clamped to zero. The alpha component is ignored, and the results are as if alpha was 1.0. This decode mode is optional and support can be queried via the physical device properties.
New Structures
New Enum Constants
Issues
1) Are implementations allowed to decode at a higher precision than what is requested?
RESOLUTION: No. If we allow this, then this extension could be exposed on all implementations that support ASTC. But developers would have no way of knowing what precision was actually used, and thus whether the image quality is sufficient at reduced precision.
2) Should the decode mode be image view state and/or sampler state?
RESOLUTION: Image view state only. Some implementations treat the different decode modes as different texture formats.
Example
Create an image view that decodes to
FORMAT_R8G8B8A8_UNORM
precision:
VkImageViewASTCDecodeModeEXT decodeMode = { .sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_ASTC_DECODE_MODE_EXT, .pNext = NULL, .decodeMode = VK_FORMAT_R8G8B8A8_UNORM }; VkImageViewCreateInfo createInfo = { .sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO, .pNext = &decodeMode, // flags, image, viewType set to application-desired values .format = VK_FORMAT_ASTC_8x8_UNORM_BLOCK, // components, subresourceRange set to application-desired values }; VkImageView imageView; VkResult result = vkCreateImageView( device, &createInfo, NULL, &imageView);
Version History
Revision 1, 2018-08-07 (Jan-Harald Fredriksen)
- Initial revision
See Also
ImageViewASTCDecodeModeEXT
, PhysicalDeviceASTCDecodeFeaturesEXT
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.
Synopsis
- data ImageViewASTCDecodeModeEXT = ImageViewASTCDecodeModeEXT {
- decodeMode :: Format
- data PhysicalDeviceASTCDecodeFeaturesEXT = PhysicalDeviceASTCDecodeFeaturesEXT {}
- type EXT_ASTC_DECODE_MODE_SPEC_VERSION = 1
- pattern EXT_ASTC_DECODE_MODE_SPEC_VERSION :: forall a. Integral a => a
- type EXT_ASTC_DECODE_MODE_EXTENSION_NAME = "VK_EXT_astc_decode_mode"
- pattern EXT_ASTC_DECODE_MODE_EXTENSION_NAME :: forall a. (Eq a, IsString a) => a
Documentation
data ImageViewASTCDecodeModeEXT Source #
VkImageViewASTCDecodeModeEXT - Structure describing the ASTC decode mode for an image view
Valid Usage
-
decodeMode
must be one ofFORMAT_R16G16B16A16_SFLOAT
,FORMAT_R8G8B8A8_UNORM
, orFORMAT_E5B9G9R9_UFLOAT_PACK32
- If the
decodeModeSharedExponent
feature is not enabled,
decodeMode
must not beFORMAT_E5B9G9R9_UFLOAT_PACK32
- If
decodeMode
isFORMAT_R8G8B8A8_UNORM
the image view must not include blocks using any of the ASTC HDR modes -
format
of the image view must be one of the ASTC Compressed Image Formats
If format
uses sRGB encoding then the decodeMode
has no effect.
Valid Usage (Implicit)
-
sType
must beSTRUCTURE_TYPE_IMAGE_VIEW_ASTC_DECODE_MODE_EXT
-
decodeMode
must be a validFormat
value
See Also
ImageViewASTCDecodeModeEXT | |
|
Instances
data PhysicalDeviceASTCDecodeFeaturesEXT Source #
VkPhysicalDeviceASTCDecodeFeaturesEXT - Structure describing ASTC decode mode features
Members
This structure describes the following feature:
Description
If the PhysicalDeviceASTCDecodeFeaturesEXT
structure is included in
the pNext
chain of the
PhysicalDeviceFeatures2
structure passed to
getPhysicalDeviceFeatures2
,
it is filled in to indicate whether each corresponding feature is
supported. PhysicalDeviceASTCDecodeFeaturesEXT
can also be used in
the pNext
chain of DeviceCreateInfo
to
selectively enable these features.
Valid Usage (Implicit)
See Also
PhysicalDeviceASTCDecodeFeaturesEXT | |
|
Instances
type EXT_ASTC_DECODE_MODE_SPEC_VERSION = 1 Source #
pattern EXT_ASTC_DECODE_MODE_SPEC_VERSION :: forall a. Integral a => a Source #
type EXT_ASTC_DECODE_MODE_EXTENSION_NAME = "VK_EXT_astc_decode_mode" Source #
pattern EXT_ASTC_DECODE_MODE_EXTENSION_NAME :: forall a. (Eq a, IsString a) => a Source #