org.lwjgl.vulkan

Class EXTAstcDecodeMode

java.lang.Object

org.lwjgl.vulkan.EXTAstcDecodeMode

public final class EXTAstcDecodeMode
extends java.lang.Object

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 =
     {
         VK_STRUCTURE_TYPE_IMAGE_VIEW_ASTC_DECODE_MODE_EXT, // sType
         NULL, // pNext
         VK_FORMAT_R8G8B8A8_UNORM // decode mode
     };
 
     VkImageViewCreateInfo createInfo =
     {
         VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO, // sType
         &decodeMode, // pNext
         // flags, image, viewType set to application-desired values
         VK_FORMAT_ASTC_8x8_UNORM_BLOCK, // format
         // components, subresourceRange set to application-desired values
     };
 
     VkImageView imageView;
     VkResult result = vkCreateImageView(
         device,
         &createInfo,
         NULL,
         &imageView);

Name String

VK_EXT_astc_decode_mode

Extension Type

Device extension

Registered Extension Number

68

Revision

1

Extension and Version Dependencies

• Requires Vulkan 1.0
• Requires VK_KHR_get_physical_device_properties2

Contact

• Jan-Harald Fredriksen janharaldfredriksen-arm

Last Modified Date

2018-08-07

Contributors

• Jan-Harald Fredriksen, Arm

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	VK_EXT_ASTC_DECODE_MODE_EXTENSION_NAME The extension name.
static int	VK_EXT_ASTC_DECODE_MODE_SPEC_VERSION The extension specification version.
static int	VK_STRUCTURE_TYPE_IMAGE_VIEW_ASTC_DECODE_MODE_EXT Extends VkStructureType.
static int	VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_ASTC_DECODE_FEATURES_EXT Extends VkStructureType.

Method Summary

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

VK_EXT_ASTC_DECODE_MODE_SPEC_VERSION

public static final int VK_EXT_ASTC_DECODE_MODE_SPEC_VERSION

The extension specification version.

See Also:

Constant Field Values

VK_EXT_ASTC_DECODE_MODE_EXTENSION_NAME

public static final java.lang.String VK_EXT_ASTC_DECODE_MODE_EXTENSION_NAME

The extension name.

See Also:

Constant Field Values

VK_STRUCTURE_TYPE_IMAGE_VIEW_ASTC_DECODE_MODE_EXT

public static final int VK_STRUCTURE_TYPE_IMAGE_VIEW_ASTC_DECODE_MODE_EXT

Extends VkStructureType.

Enum values:

• STRUCTURE_TYPE_IMAGE_VIEW_ASTC_DECODE_MODE_EXT
• STRUCTURE_TYPE_PHYSICAL_DEVICE_ASTC_DECODE_FEATURES_EXT

See Also:

Constant Field Values

VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_ASTC_DECODE_FEATURES_EXT

public static final int VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_ASTC_DECODE_FEATURES_EXT

Extends VkStructureType.

Enum values:

• STRUCTURE_TYPE_IMAGE_VIEW_ASTC_DECODE_MODE_EXT
• STRUCTURE_TYPE_PHYSICAL_DEVICE_ASTC_DECODE_FEATURES_EXT

See Also:

Constant Field Values