Package org.lwjgl.vulkan
Class EXTAstcDecodeMode
java.lang.Object
org.lwjgl.vulkan.EXTAstcDecodeMode
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.
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);
VK_EXT_astc_decode_mode
- Name String
VK_EXT_astc_decode_mode
- Extension Type
- Device extension
- Registered Extension Number
- 68
- Revision
- 1
- Extension and Version Dependencies
VK_KHR_get_physical_device_properties2
or Version 1.1- Contact
- Jan-Harald Fredriksen janharaldfredriksen-arm
Other Extension Metadata
- Last Modified Date
- 2018-08-07
- Contributors
- Jan-Harald Fredriksen, Arm
-
Field Summary
Modifier and TypeFieldDescriptionstatic final String
The extension name.static final int
The extension specification version.static final int
ExtendsVkStructureType
.static final int
ExtendsVkStructureType
. -
Method Summary
-
Field Details
-
VK_EXT_ASTC_DECODE_MODE_SPEC_VERSION
public static final int VK_EXT_ASTC_DECODE_MODE_SPEC_VERSIONThe extension specification version.- See Also:
-
VK_EXT_ASTC_DECODE_MODE_EXTENSION_NAME
The extension name.- See Also:
-
VK_STRUCTURE_TYPE_IMAGE_VIEW_ASTC_DECODE_MODE_EXT
public static final int VK_STRUCTURE_TYPE_IMAGE_VIEW_ASTC_DECODE_MODE_EXTExtendsVkStructureType
.Enum values:
- See Also:
-
VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_ASTC_DECODE_FEATURES_EXT
public static final int VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_ASTC_DECODE_FEATURES_EXTExtendsVkStructureType
.Enum values:
- See Also:
-