VkImageLayout
The set of image layouts consists of:
typedef enum VkImageLayout {
VK_IMAGE_LAYOUT_UNDEFINED = 0,
VK_IMAGE_LAYOUT_GENERAL = 1,
VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL = 2,
VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL = 3,
VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL = 4,
VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL = 5,
VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL = 6,
VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL = 7,
VK_IMAGE_LAYOUT_PREINITIALIZED = 8,
} VkImageLayout;
The type(s) of device access supported by each layout are:
VK_IMAGE_LAYOUT_UNDEFINEDspecifies that the layout is unknown. Image memory cannot be transitioned into this layout. This layout can be used as theinitialLayoutmember of VkImageCreateInfo. This layout can be used in place of the current image layout in a layout transition, but doing so will cause the contents of the image’s memory to be undefined:.VK_IMAGE_LAYOUT_PREINITIALIZEDspecifies that an image’s memory is in a defined layout and can be populated by data, but that it has not yet been initialized by the driver. Image memory cannot be transitioned into this layout. This layout can be used as theinitialLayoutmember of VkImageCreateInfo. This layout is intended to be used as the initial layout for an image whose contents are written by the host, and hence the data can be written to memory immediately, without first executing a layout transition. Currently,VK_IMAGE_LAYOUT_PREINITIALIZEDis only useful with linear images because there is not a standard layout defined forVK_IMAGE_TILING_OPTIMALimages.VK_IMAGE_LAYOUT_GENERALsupports all types of device access, unless specified otherwise.VK_IMAGE_LAYOUT_ATTACHMENT_OPTIMALspecifies a layout that must only be used with attachment accesses in the graphics pipeline.VK_IMAGE_LAYOUT_READ_ONLY_OPTIMALspecifies a layout allowing read only access as an attachment, or in shaders as a sampled image, combined image/sampler, or input attachment.VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMALmust only be used as a color or resolve attachment in aVkFramebuffer. This layout is valid only for image subresources of images created with theVK_IMAGE_USAGE_COLOR_ATTACHMENT_BITusage bit enabled.VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMALspecifies a layout for both the depth and stencil aspects of a depth/stencil format image allowing read and write access as a depth/stencil attachment. It is equivalent toVK_IMAGE_LAYOUT_DEPTH_ATTACHMENT_OPTIMALandVK_IMAGE_LAYOUT_STENCIL_ATTACHMENT_OPTIMAL.VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMALspecifies a layout for both the depth and stencil aspects of a depth/stencil format image allowing read only access as a depth/stencil attachment or in shaders as a sampled image, combined image/sampler, or input attachment. It is equivalent toVK_IMAGE_LAYOUT_DEPTH_READ_ONLY_OPTIMALandVK_IMAGE_LAYOUT_STENCIL_READ_ONLY_OPTIMAL.VK_IMAGE_LAYOUT_DEPTH_READ_ONLY_STENCIL_ATTACHMENT_OPTIMALspecifies a layout for depth/stencil format images allowing read and write access to the stencil aspect as a stencil attachment, and read only access to the depth aspect as a depth attachment or in shaders as a sampled image, combined image/sampler, or input attachment. It is equivalent toVK_IMAGE_LAYOUT_DEPTH_READ_ONLY_OPTIMALandVK_IMAGE_LAYOUT_STENCIL_ATTACHMENT_OPTIMAL.VK_IMAGE_LAYOUT_DEPTH_ATTACHMENT_STENCIL_READ_ONLY_OPTIMALspecifies a layout for depth/stencil format images allowing read and write access to the depth aspect as a depth attachment, and read only access to the stencil aspect as a stencil attachment or in shaders as a sampled image, combined image/sampler, or input attachment. It is equivalent toVK_IMAGE_LAYOUT_DEPTH_ATTACHMENT_OPTIMALandVK_IMAGE_LAYOUT_STENCIL_READ_ONLY_OPTIMAL.VK_IMAGE_LAYOUT_DEPTH_ATTACHMENT_OPTIMALspecifies a layout for the depth aspect of a depth/stencil format image allowing read and write access as a depth attachment.VK_IMAGE_LAYOUT_DEPTH_READ_ONLY_OPTIMALspecifies a layout for the depth aspect of a depth/stencil format image allowing read-only access as a depth attachment or in shaders as a sampled image, combined image/sampler, or input attachment.VK_IMAGE_LAYOUT_STENCIL_ATTACHMENT_OPTIMALspecifies a layout for the stencil aspect of a depth/stencil format image allowing read and write access as a stencil attachment.VK_IMAGE_LAYOUT_STENCIL_READ_ONLY_OPTIMALspecifies a layout for the stencil aspect of a depth/stencil format image allowing read-only access as a stencil attachment or in shaders as a sampled image, combined image/sampler, or input attachment.VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMALspecifies a layout allowing read-only access in a shader as a sampled image, combined image/sampler, or input attachment. This layout is valid only for image subresources of images created with theVK_IMAGE_USAGE_SAMPLED_BITorVK_IMAGE_USAGE_INPUT_ATTACHMENT_BITusage bits enabled.VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMALmust only be used as a source image of a transfer command (see the definition ofVK_PIPELINE_STAGE_TRANSFER_BIT). This layout is valid only for image subresources of images created with theVK_IMAGE_USAGE_TRANSFER_SRC_BITusage bit enabled.VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMALmust only be used as a destination image of a transfer command. This layout is valid only for image subresources of images created with theVK_IMAGE_USAGE_TRANSFER_DST_BITusage bit enabled.VK_IMAGE_LAYOUT_PRESENT_SRC_KHRmust only be used for presenting a presentable image for display.VK_IMAGE_LAYOUT_SHARED_PRESENT_KHRis valid only for shared presentable images, and must be used for any usage the image supports.VK_IMAGE_LAYOUT_FRAGMENT_SHADING_RATE_ATTACHMENT_OPTIMAL_KHRmust only be used as a fragment shading rate attachment or shading rate image. This layout is valid only for image subresources of images created with theVK_IMAGE_USAGE_FRAGMENT_SHADING_RATE_ATTACHMENT_BIT_KHRusage bit enabled.VK_IMAGE_LAYOUT_FRAGMENT_DENSITY_MAP_OPTIMAL_EXTmust only be used as a fragment density map attachment in aVkRenderPass. This layout is valid only for image subresources of images created with theVK_IMAGE_USAGE_FRAGMENT_DENSITY_MAP_BIT_EXTusage bit enabled.VK_IMAGE_LAYOUT_VIDEO_DECODE_DST_KHRmust only be used as a decode output picture in a video decode operation. This layout is valid only for image subresources of images created with theVK_IMAGE_USAGE_VIDEO_DECODE_DST_BIT_KHRusage bit enabled.VK_IMAGE_LAYOUT_VIDEO_DECODE_SRC_KHRis reserved for future use.VK_IMAGE_LAYOUT_VIDEO_DECODE_DPB_KHRmust only be used as an output reconstructed picture or an input reference picture in a video decode operation. This layout is valid only for image subresources of images created with theVK_IMAGE_USAGE_VIDEO_DECODE_DPB_BIT_KHRusage bit enabled.VK_IMAGE_LAYOUT_VIDEO_ENCODE_DST_KHRis reserved for future use.VK_IMAGE_LAYOUT_VIDEO_ENCODE_SRC_KHRmust only be used as an encode input picture in a video encode operation. This layout is valid only for image subresources of images created with theVK_IMAGE_USAGE_VIDEO_ENCODE_SRC_BIT_KHRusage bit enabled.VK_IMAGE_LAYOUT_VIDEO_ENCODE_DPB_KHRmust only be used as an output reconstructed picture or an input reference picture in a video encode operation. This layout is valid only for image subresources of images created with theVK_IMAGE_USAGE_VIDEO_ENCODE_DPB_BIT_KHRusage bit enabled.VK_IMAGE_LAYOUT_ATTACHMENT_FEEDBACK_LOOP_OPTIMAL_EXTmust only be used as either a color attachment or depth/stencil attachment in aVkFramebufferand/or read-only access in a shader as a sampled image, combined image/sampler, or input attachment. This layout is valid only for image subresources of images created with theVK_IMAGE_USAGE_ATTACHMENT_FEEDBACK_LOOP_BIT_EXTusage bit enabled and either theVK_IMAGE_USAGE_COLOR_ATTACHMENT_BITorVK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BITand either theVK_IMAGE_USAGE_INPUT_ATTACHMENT_BITorVK_IMAGE_USAGE_SAMPLED_BITusage bits enabled.VK_IMAGE_LAYOUT_RENDERING_LOCAL_READmust only be used as either a storage image, or a color or depth/stencil attachment and an input attachment. This layout is valid only for image subresources of images created with eitherVK_IMAGE_USAGE_STORAGE_BIT, or bothVK_IMAGE_USAGE_INPUT_ATTACHMENT_BITand either ofVK_IMAGE_USAGE_COLOR_ATTACHMENT_BITorVK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT.VK_IMAGE_LAYOUT_VIDEO_ENCODE_QUANTIZATION_MAP_KHRmust only be used as a quantization map in a video encode operation. This layout is valid only for image subresources of images created with theVK_IMAGE_USAGE_VIDEO_ENCODE_QUANTIZATION_DELTA_MAP_BIT_KHRorVK_IMAGE_USAGE_VIDEO_ENCODE_EMPHASIS_MAP_BIT_KHRusage bit enabled.
The layout of each image subresource is not a state of the image subresource
itself, but is rather a property of how the data in memory is organized, and
thus for each mechanism of accessing an image in the API the application
must specify a parameter or structure member that indicates which image
layout the image subresource(s) are considered to be in when the image will
be accessed.
For transfer commands, this is a parameter to the command (see Clear Commands
and Copy Commands).
For use as a framebuffer attachment, this is a member in the substructures
of the VkRenderPassCreateInfo (see Render Pass).
For use in a descriptor set, this is a member in the
VkDescriptorImageInfo structure (see Descriptor Set Updates).
VK_IMAGE_LAYOUT_GENERAL can be a useful catch-all image layout, but
there are situations where a dedicated image layout must be used instead.
Some examples include:
VK_IMAGE_LAYOUT_PRESENT_SRC_KHRVK_IMAGE_LAYOUT_VIDEO_DECODE_SRC_KHRVK_IMAGE_LAYOUT_VIDEO_DECODE_DST_KHRVK_IMAGE_LAYOUT_VIDEO_DECODE_DPB_KHRVK_IMAGE_LAYOUT_VIDEO_ENCODE_SRC_KHRVK_IMAGE_LAYOUT_VIDEO_ENCODE_DST_KHRVK_IMAGE_LAYOUT_VIDEO_ENCODE_DPB_KHR
While VK_IMAGE_LAYOUT_GENERAL suggests that all types of device access
is possible, it does not mean that all patterns of memory accesses are safe
in all situations.
Common Render Pass Data Races outlines
some situations where data races are unavoidable.
For example, when a subresource is used as both an attachment and a sampled
image (i.e., not an input attachment),
VK_IMAGE_LAYOUT_ATTACHMENT_FEEDBACK_LOOP_OPTIMAL_EXT adds extra
guarantees which VK_IMAGE_LAYOUT_GENERAL does not.