// Copyright (c) 2015-2016 The Khronos Group Inc. // Copyright notice at https://www.khronos.org/registry/speccopyright.html [[resources]] = Resource Creation {apiname} supports two primary resource types: _buffers_ and _images_. Resources are views of memory with associated formatting and dimensionality. Buffers are essentially unformatted arrays of bytes whereas images contain format information, can: be multidimensional and may: have associated metadata. [[resources-buffers]] == Buffers Buffers represent linear arrays of data which are used for various purposes by binding them to the graphics pipeline via descriptor sets or via certain commands, or by directly specifying them as parameters to certain commands. Buffers are created by calling: include::../protos/vkCreateBuffer.txt[] * pname:device is the logical device that creates the buffer object. * pname:pCreateInfo is a pointer to an instance of the sname:VkBufferCreateInfo structure containing parameters affecting creation of the buffer. * pname:pAllocator controls host memory allocation as described in the <> chapter. * pname:pBuffer points to a sname:VkBuffer handle in which the resulting buffer object is returned. include::../validity/protos/vkCreateBuffer.txt[] The definition of sname:VkBufferCreateInfo is: include::../structs/VkBufferCreateInfo.txt[] The members of sname:VkBufferCreateInfo have the following meanings: * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:flags is a bitfield describing additional parameters of the buffer. See elink:VkBufferCreateFlagBits below for a description of the supported bits. * pname:size is the size in bytes of the buffer to be created. * pname:usage is a bitfield describing the allowed usages of the buffer. See elink:VkBufferUsageFlagBits below for a description of the supported bits. * pname:sharingMode is the sharing mode of the buffer when it will be accessed by multiple queue families, see elink:VkSharingMode in the <> section below for supported values. * pname:queueFamilyIndexCount is the number of entries in the pname:pQueueFamilyIndices array. * pname:pQueueFamilyIndices is a list of queue families that will access this buffer (ignored if pname:sharingMode is not ename:VK_SHARING_MODE_CONCURRENT). include::../validity/structs/VkBufferCreateInfo.txt[] Bits which may: be set in pname:usage are: include::../enums/VkBufferUsageFlagBits.txt[] * ename:VK_BUFFER_USAGE_TRANSFER_SRC_BIT indicates that the buffer can: be used as the source of a _transfer command_ (see the definition of <>). * ename:VK_BUFFER_USAGE_TRANSFER_DST_BIT indicates that the buffer can: be used as the destination of a transfer command. * ename:VK_BUFFER_USAGE_UNIFORM_TEXEL_BUFFER_BIT indicates that the buffer can: be used to create a sname:VkBufferView suitable for occupying a sname:VkDescriptorSet slot of type ename:VK_DESCRIPTOR_TYPE_UNIFORM_TEXEL_BUFFER. * ename:VK_BUFFER_USAGE_STORAGE_TEXEL_BUFFER_BIT indicates that the buffer can: be used to create a sname:VkBufferView suitable for occupying a sname:VkDescriptorSet slot of type ename:VK_DESCRIPTOR_TYPE_STORAGE_TEXEL_BUFFER. * ename:VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT indicates that the buffer can: be used in a sname:VkDescriptorBufferInfo suitable for occupying a sname:VkDescriptorSet slot either of type ename:VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER or ename:VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER_DYNAMIC. * ename:VK_BUFFER_USAGE_STORAGE_BUFFER_BIT indicates that the buffer can: be used in a sname:VkDescriptorBufferInfo suitable for occupying a sname:VkDescriptorSet slot either of type ename:VK_DESCRIPTOR_TYPE_STORAGE_BUFFER or ename:VK_DESCRIPTOR_TYPE_STORAGE_BUFFER_DYNAMIC. * ename:VK_BUFFER_USAGE_INDEX_BUFFER_BIT indicates that the buffer is suitable for passing as the pname:buffer parameter to fname:vkCmdBindIndexBuffer. * ename:VK_BUFFER_USAGE_VERTEX_BUFFER_BIT indicates that the buffer is suitable for passing as an element of the pname:pBuffers array to fname:vkCmdBindVertexBuffers. * ename:VK_BUFFER_USAGE_INDIRECT_BUFFER_BIT indicates that the buffer is suitable for passing as the pname:buffer parameter to fname:vkCmdDrawIndirect, fname:vkCmdDrawIndexedIndirect, or fname:vkCmdDispatchIndirect. Any combination of bits can: be specified for pname:usage, but at least one of the bits must: be set in order to create a valid buffer. Bits which may: be set in pname:flags are: include::../enums/VkBufferCreateFlagBits.txt[] These bitfields have the following meanings: * ename:VK_BUFFER_CREATE_SPARSE_BINDING_BIT indicates that the buffer will be backed using sparse memory binding. * ename:VK_BUFFER_CREATE_SPARSE_RESIDENCY_BIT indicates that the buffer can: be partially backed using sparse memory binding. * ename:VK_BUFFER_CREATE_SPARSE_ALIASED_BIT indicates that the buffer will be backed using sparse memory binding with memory ranges that might also simultaneously be backing another buffer (or another portion of the same buffer). See <> and <> for details of the sparse memory features supported on a device. To destroy a buffer, call: include::../protos/vkDestroyBuffer.txt[] * pname:device is the logical device that destroys the buffer. * pname:buffer is the buffer to destroy. * pname:pAllocator controls host memory allocation as described in the <> chapter. include::../validity/protos/vkDestroyBuffer.txt[] [[resources-buffer-views]] == Buffer Views A _buffer view_ represents a contiguous range of a buffer and a specific format to be used to interpret the data. Buffer views are used to enable shaders to access buffer contents interpreted as formatted data. In order to create a valid buffer view, the buffer must: have been created with at least one of the following usage flags: * ename:VK_BUFFER_USAGE_UNIFORM_TEXEL_BUFFER_BIT * ename:VK_BUFFER_USAGE_STORAGE_TEXEL_BUFFER_BIT A buffer view is created by calling: include::../protos/vkCreateBufferView.txt[] * pname:device is the logical device that creates the buffer view. * pname:pCreateInfo is a pointer to an instance of the sname:VkBufferViewCreateInfo structure containing parameters to be used to create the buffer. * pname:pAllocator controls host memory allocation as described in the <> chapter. * pname:pView points to a sname:VkBufferView handle in which the resulting buffer view object is returned. include::../validity/protos/vkCreateBufferView.txt[] The definition of sname:VkBufferViewCreateInfo is: include::../structs/VkBufferViewCreateInfo.txt[] The members of sname:VkBufferViewCreateInfo have the following meanings: * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:flags is reserved for future use. * pname:buffer is a sname:VkBuffer on which the view will be created. * pname:format is a elink:VkFormat describing the format of the data elements in the buffer. * pname:offset is an offset in bytes from the base address of the buffer. Accesses to the buffer view from shaders use addressing that is relative to this starting offset. * pname:range is a size in bytes of the buffer view. If pname:range is equal to ename:VK_WHOLE_SIZE, the range from pname:offset to the end of the buffer is used. If ename:VK_WHOLE_SIZE is used and the remaining size of the buffer is not a multiple of the element size of pname:format, then the nearest smaller multiple is used. include::../validity/structs/VkBufferViewCreateInfo.txt[] To destroy a buffer view, call: include::../protos/vkDestroyBufferView.txt[] * pname:device is the logical device that destroys the buffer view. * pname:bufferView is the buffer view to destroy. * pname:pAllocator controls host memory allocation as described in the <> chapter. include::../validity/protos/vkDestroyBufferView.txt[] [[resources-images]] == Images Images represent multidimensional - up to 3 - arrays of data which can: be used for various purposes (e.g. attachments, textures), by binding them to the graphics pipeline via descriptor sets, or by directly specifying them as parameters to certain commands. Images are created by calling: include::../protos/vkCreateImage.txt[] * pname:device is the logical device that creates the image. * pname:pCreateInfo is a pointer to an instance of the sname:VkImageCreateInfo structure containing parameters to be used to create the image. * pname:pAllocator controls host memory allocation as described in the <> chapter. * pname:pImage points to a sname:VkImage handle in which the resulting image object is returned. include::../validity/protos/vkCreateImage.txt[] The definition of sname:VkImageCreateInfo is: include::../structs/VkImageCreateInfo.txt[] The members of sname:VkImageCreateInfo have the following meanings: * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:flags is a bitfield describing additional parameters of the image. See elink:VkImageCreateFlagBits below for a description of the supported bits. * pname:imageType is the basic dimensionality of the image, and must: be one of the values + -- include::../enums/VkImageType.txt[] specifying one-, two-, or three-dimensionality, respectively. Layers in array textures do not count as a dimension for the purposes of the image type. -- * pname:format is a elink:VkFormat describing the format and type of the data elements that will be contained in the image. * pname:extent is a slink:VkExtent3D describing the number of data elements in each dimension of the base level. * pname:mipLevels describes the number of levels of detail available for minified sampling of the image. * pname:arrayLayers is the number of layers in the image. * pname:samples is the number of sub-data element samples in the image as defined in elink:VkSampleCountFlagBits. See <>. * pname:tiling is the tiling arrangement of the data elements in memory, and must: have one of the values: + -- include::../enums/VkImageTiling.txt[] ename:VK_IMAGE_TILING_OPTIMAL specifies optimal tiling (texels are laid out in an implementation-dependent arrangement, for more optimal memory access), and ename:VK_IMAGE_TILING_LINEAR specifies linear tiling (texels are laid out in memory in row-major order, possibly with some padding on each row). -- * pname:usage is a bitfield describing the intended usage of the image. See elink:VkImageUsageFlagBits below for a description of the supported bits. * pname:sharingMode is the sharing mode of the image when it will be accessed by multiple queue families, and must: be one of the values described for elink:VkSharingMode in the <> section below. * pname:queueFamilyIndexCount is the number of entries in the pname:pQueueFamilyIndices array. * pname:pQueueFamilyIndices is a list of queue families that will access this image (ignored if pname:sharingMode is not ename:VK_SHARING_MODE_CONCURRENT). * pname:initialLayout selects the initial elink:VkImageLayout state of all subresources of the image. See <>. pname:initialLayout must: be ename:VK_IMAGE_LAYOUT_UNDEFINED or ename:VK_IMAGE_LAYOUT_PREINITIALIZED. include::../validity/structs/VkImageCreateInfo.txt[] Valid limits for the image pname:extent, pname:mipLevels, pname:arrayLayers and pname:samples members are queried with the flink:vkGetPhysicalDeviceImageFormatProperties command. Images created with pname:tiling equal to ename:VK_IMAGE_TILING_LINEAR have further restrictions on their limits and capabilities compared to images created with pname:tiling equal to ename:VK_IMAGE_TILING_OPTIMAL. Creation of images with tiling ename:VK_IMAGE_TILING_LINEAR maynot: be supported unless other parameters meet all of the constraints: * pname:imageType is ename:VK_IMAGE_TYPE_2D * pname:format is not a depth/stencil format * pname:mipLevels is 1 * pname:arrayLayers is 1 * pname:samples is ename:VK_SAMPLE_COUNT_1_BIT * pname:usage only includes ename:VK_IMAGE_USAGE_TRANSFER_SRC_BIT and/or ename:VK_IMAGE_USAGE_TRANSFER_DST_BIT Implementations may: support additional limits and capabilities beyond those listed above. To determine the specific capabilities of an implementation, query the valid pname:usage bits by calling flink:vkGetPhysicalDeviceFormatProperties and the valid limits for pname:mipLevels and pname:arrayLayers by calling flink:vkGetPhysicalDeviceImageFormatProperties. Bits which may: be set in pname:usage are: include::../enums/VkImageUsageFlagBits.txt[] These bitfields have the following meanings: * ename:VK_IMAGE_USAGE_TRANSFER_SRC_BIT indicates that the image can: be used as the source of a transfer command. * ename:VK_IMAGE_USAGE_TRANSFER_DST_BIT indicates that the image can: be used as the destination of a transfer command. * ename:VK_IMAGE_USAGE_SAMPLED_BIT indicates that the image can: be used to create a sname:VkImageView suitable for occupying a sname:VkDescriptorSet slot either of type ename:VK_DESCRIPTOR_TYPE_SAMPLED_IMAGE or ename:VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, and be sampled by a shader. * ename:VK_IMAGE_USAGE_STORAGE_BIT indicates that the image can: be used to create a sname:VkImageView suitable for occupying a sname:VkDescriptorSet slot of type ename:VK_DESCRIPTOR_TYPE_STORAGE_IMAGE. * ename:VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT indicates that the image can: be used to create a sname:VkImageView suitable for use as a color or resolve attachment in a sname:VkFramebuffer. * ename:VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT indicates that the image can: be used to create a sname:VkImageView suitable for use as a depth/stencil attachment in a sname:VkFramebuffer. * ename:VK_IMAGE_USAGE_TRANSIENT_ATTACHMENT_BIT indicates that the memory bound to this image will have been allocated with the ename:VK_MEMORY_PROPERTY_LAZILY_ALLOCATED_BIT (see <> for more detail). If this is set, then bits other than ename:VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT, ename:VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT, and ename:VK_IMAGE_USAGE_INPUT_ATTACHMENT_BIT mustnot: be set. * ename:VK_IMAGE_USAGE_INPUT_ATTACHMENT_BIT indicates that the image can: be used to create a sname:VkImageView suitable for occupying sname:VkDescriptorSet slot of type ename:VK_DESCRIPTOR_TYPE_INPUT_ATTACHMENT; be read from a shader as an input attachment; and be used as an input attachment in a framebuffer. Bits which may: be set in pname:flags are: include::../enums/VkImageCreateFlagBits.txt[] These bitfields have the following meanings: * ename:VK_IMAGE_CREATE_SPARSE_BINDING_BIT indicates that the image will be backed using sparse memory binding. * ename:VK_IMAGE_CREATE_SPARSE_RESIDENCY_BIT indicates that the image can: be partially backed using sparse memory binding. * ename:VK_IMAGE_CREATE_SPARSE_ALIASED_BIT indicates that the image will be backed using sparse memory binding with memory ranges that might also simultaneously be backing another image (or another portion of the same image). Sparse images created with this flag must: also be created with the ename:VK_IMAGE_CREATE_SPARSE_RESIDENCY_BIT. If any of these three bits are set, ename:VK_IMAGE_USAGE_TRANSIENT_ATTACHMENT_BIT mustnot: also be set. See <> and <> for more details. * ename:VK_IMAGE_CREATE_MUTABLE_FORMAT_BIT indicates that the image can: be used to create a slink:VkImageView with a different format from the image. * ename:VK_IMAGE_CREATE_CUBE_COMPATIBLE_BIT indicates that the image can: be used to create a slink:VkImageView of type ename:VK_IMAGE_VIEW_TYPE_CUBE or ename:VK_IMAGE_VIEW_TYPE_CUBE_ARRAY. The layout of a subresource (mipLevel/arrayLayer) of an image created with linear tiling is queried by calling: include::../protos/vkGetImageSubresourceLayout.txt[] * pname:device is the logical device that owns the image. * pname:image is the image whose layout is being queried. * pname:pSubresource is a pointer to a slink:VkImageSubresource structure selecting a specific image for the subresource. * pname:pLayout points to a slink:VkSubresourceLayout structure in which the layout is returned. include::../validity/protos/vkGetImageSubresourceLayout.txt[] The definition of the sname:VkImageSubresource structure is: include::../structs/VkImageSubresource.txt[] * pname:aspectMask is a elink:VkImageAspectFlags selecting the image aspect. * pname:mipLevel selects the mipmap level. * pname:arrayLayer selects the array layer. include::../validity/structs/VkImageSubresource.txt[] Information about the layout of the subresource is returned in a sname:VkSubresourceLayout structure: include::../structs/VkSubresourceLayout.txt[] * pname:offset is the byte offset from the start of the image where the subresource begins. * pname:size is the size in bytes of the subresource. pname:size includes any extra memory that is required based on the value of pname:rowPitch. * pname:rowPitch describes the number of bytes between each row of texels in an image. * pname:arrayPitch describes the number of bytes between each array layer of an image. * pname:depthPitch describes the number of bytes between each slice of 3D image. include::../validity/structs/VkSubresourceLayout.txt[] For images created with linear tiling, pname:rowPitch, pname:arrayPitch and pname:depthPitch describe the layout of the subresource in linear memory. For uncompressed formats, pname:rowPitch is the number of bytes between texels with the same x coordinate in adjacent rows (y coordinates differ by one). pname:arrayPitch is the number of bytes between texels with the same x and y coordinate in adjacent array layers of the image (array layer values differ by one). pname:depthPitch is the number of bytes between texels with the same x and y coordinate in adjacent slices of a 3D image (z coordinates differ by one). Expressed as an addressing formula, the starting byte of a texel in the subresource has address: [source,c] --------------------------------------------------- // (x,y,z,layer) are in texel coordinates address(x,y,z,layer) = layer*arrayPitch + z*depthPitch + y*rowPitch + x*texelSize + offset --------------------------------------------------- For compressed formats, the pname:rowPitch is the number of bytes between compressed blocks in adjacent rows. pname:arrayPitch is the number of bytes between blocks in adjacent array layers. pname:depthPitch is the number of bytes between blocks in adjacent slices of a 3D image. [source,c] --------------------------------------------------- // (x,y,z,layer) are in block coordinates address(x,y,z,layer) = layer*arrayPitch + z*depthPitch + y*rowPitch + x*blockSize + offset; --------------------------------------------------- pname:arrayPitch is undefined for images that were not created as arrays. pname:depthPitch is defined only for 3D images. For color formats, the pname:aspectMask member of sname:VkImageSubresource must: be ename:VK_IMAGE_ASPECT_COLOR_BIT. For depth/stencil formats, pname:aspect must: be either ename:VK_IMAGE_ASPECT_DEPTH_BIT or ename:VK_IMAGE_ASPECT_STENCIL_BIT. On implementations that store depth and stencil aspects separately, querying each of these subresource layouts will return a different pname:offset and pname:size representing the region of memory used for that aspect. On implementations that store depth and stencil aspects interleaved, the same pname:offset and pname:size are returned and represent the interleaved memory allocation. To destroy an image, call: include::../protos/vkDestroyImage.txt[] * pname:device is the logical device that destroys the image. * pname:image is the image to destroy. * pname:pAllocator controls host memory allocation as described in the <> chapter. include::../validity/protos/vkDestroyImage.txt[] [[resources-image-layouts]] == Image Layouts Images are stored in implementation-dependent opaque layouts in memory. Implementations may: support several opaque layouts, and the layout used at any given time is determined by the elink:VkImageLayout state of the subresource. Each layout has limitations on what kinds of operations are supported for subresources using the layout. Applications have control over which layout each image subresource uses, and can: transition an image subresource from one layout to another. Transitions can: happen with an image memory barrier, included as part of a fname:vkCmdPipelineBarrier or a fname:vkCmdWaitEvents command buffer command (see <>), or as part of a subpass dependency within a render pass (see sname:VkSubpassDependency). The image layout state is per-subresource, and separate subresources of the same image can: be in different layouts at the same time with one exception - depth and stencil aspects of a given subresource must: always be in the same layout. [NOTE] .Note ==== Each layout may: offer optimal performance for a specific usage of image memory. For example, an image with a layout of ename:VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL may: provide optimal performance for use as a color attachment, but be unsupported for use in transfer commands. Applications can: transition an image subresource from one layout to another in order to achieve optimal performance when the subresource is used for multiple kinds of operations. After initialization, applications need not use any layout other than the general layout, though this may: produce suboptimal performance on some implementations. ==== Upon creation, all subresources of an image are initially in the same layout, where that layout is selected by the sname:VkImageCreateInfo::pname:initialLayout member. The pname:initialLayout must: be either ename:VK_IMAGE_LAYOUT_UNDEFINED or ename:VK_IMAGE_LAYOUT_PREINITIALIZED. If it is ename:VK_IMAGE_LAYOUT_PREINITIALIZED, then the image data can: be pre-initialized by the host while using this layout, and the transition away from this layout will preserve that data. If it is ename:VK_IMAGE_LAYOUT_UNDEFINED, then the contents of the data are considered to be undefined, and the transition away from this layout is not guaranteed to preserve that data. For either of these initial layouts, any subresources must: be transitioned to another layout before they are accessed by the device. Host access to image memory is only well-defined for images created with ename:VK_IMAGE_TILING_LINEAR tiling and for subresources of those images which are currently in either the ename:VK_IMAGE_LAYOUT_PREINITIALIZED or ename:VK_IMAGE_LAYOUT_GENERAL layout. The set of image layouts consists of: include::../enums/VkImageLayout.txt[] The type(s) of device access supported by each layout are: * ename:VK_IMAGE_LAYOUT_UNDEFINED: Supports no device access. This layout must: only be used as an pname:initialLayout or as the pname:oldLayout in an image transition. When transitioning out of this layout, the contents of the memory are not guaranteed to be preserved. * ename:VK_IMAGE_LAYOUT_PREINITIALIZED: Supports no device access. This layout must: only be used as an pname:initialLayout or as the pname:oldLayout in an image transition. When transitioning out of this layout, the contents of the memory are preserved. 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, ename:VK_IMAGE_LAYOUT_PREINITIALIZED is only useful with ename:VK_IMAGE_TILING_LINEAR images because there is not a standard layout defined for ename:VK_IMAGE_TILING_OPTIMAL images. * ename:VK_IMAGE_LAYOUT_GENERAL: Supports all types of device access. * ename:VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL: must: only be used as a color or resolve attachment in a sname:VkFramebuffer. This layout is valid only for subresources of images created with the ename:VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT usage bit enabled. * ename:VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL: must: only be used as a depth/stencil attachment in a sname:VkFramebuffer. This layout is valid only for subresources of images created with the ename:VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT usage bit enabled. * ename:VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL: must: only be used as a read-only depth/stencil attachment in a sname:VkFramebuffer and/or as a read-only image in a shader (which can: be read as a sampled image, combined image/sampler and/or input attachment). This layout is valid only for subresources of images created with both the ename:VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT usage bit enabled. * ename:VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL: must: only be used as a read-only image in a shader (which can: be read as a sampled image, combined image/sampler and/or input attachment). This layout is valid only for subresources of images created with the ename:VK_IMAGE_USAGE_SAMPLED_BIT or ename:VK_IMAGE_USAGE_INPUT_ATTACHMENT_BIT usage bit enabled. * ename:VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL: must: only be used as a source image of a transfer command (see the definition of <>). This layout is valid only for subresources of images created with the ename:VK_IMAGE_USAGE_TRANSFER_SRC_BIT usage bit enabled. * ename:VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL: must: only be used as a destination image of a transfer command. This layout is valid only for subresources of images created with the ename:VK_IMAGE_USAGE_TRANSFER_DST_BIT usage bit enabled. For each mechanism of accessing an image in the API, there is a parameter or structure member that controls the image layout used to access the image. For transfer commands, this is a parameter to the command (see <> and <>). For use as a framebuffer attachment, this is a member in the substructures of the sname:VkRenderPassCreateInfo (see <>). For use in a descriptor set, this is a member in the sname:VkDescriptorImageInfo structure (see <>). At the time that any command buffer command accessing an image executes on any queue, the layouts of the image subresources that are accessed must: all match the layout specified via the API controlling those accesses. The image layout of each image subresource must: be well-defined at each point in the subresource's lifetime. This means that when performing a layout transition on the subresource, the old layout value must: either equal the current layout of the subresource (at the time the transition executes), or else be ename:VK_IMAGE_LAYOUT_UNDEFINED (implying that the contents of the subresource need not be preserved). The new layout used in a transition mustnot: be ename:VK_IMAGE_LAYOUT_UNDEFINED or ename:VK_IMAGE_LAYOUT_PREINITIALIZED. [[resources-image-views]] == Image Views Image objects are not directly accessed by pipeline shaders for reading or writing image data. Instead, _image views_ representing contiguous ranges of the image subresources and containing additional metadata are used for that purpose. Views must: be created on images of compatible types, and must: represent a valid subset of image subresources. The types of image views that can: be created are: include::../enums/VkImageViewType.txt[] The exact image view type is partially implicit, based on the image's type and sample count, as well as the view creation parameters as described in the <>. This table also shows which SPIR-V OpTypeImage Dim and Arrayed parameters correspond to each image view type. To create an image view, call: include::../protos/vkCreateImageView.txt[] * pname:device is the logical device that creates the image view. * pname:pCreateInfo is a pointer to an instance of the sname:VkImageViewCreateInfo structure containing parameters to be used to create the image view. * pname:pAllocator controls host memory allocation as described in the <> chapter. * pname:pView points to a sname:VkImageView handle in which the resulting image view object is returned. Some of the image creation parameters are inherited by the view. The remaining parameters are contained in the pname:pCreateInfo. include::../validity/protos/vkCreateImageView.txt[] The sname:VkImageViewCreateInfo structure is defined as: include::../structs/VkImageViewCreateInfo.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:flags is reserved for future use. * pname:image is a sname:VkImage on which the view will be created. * pname:viewType is the type of the image view. * pname:format is a elink:VkFormat describing the format and type used to interpret data elements in the image. * pname:components specifies a remapping of color components (or of depth or stencil components after they have been converted into color components). See slink:VkComponentMapping. * pname:subresourceRange selects the set of mipmap levels and array layers to be accessible to the view. include::../validity/structs/VkImageViewCreateInfo.txt[] If pname:image was created with the ename:VK_IMAGE_CREATE_MUTABLE_FORMAT_BIT flag, pname:format can: be different from the image's format, but if they are not equal they must: be _compatible_. Image format compatibility is defined in the <> section. [[resources-image-views-compatibility]] .Image and image view parameter compatibility requirements [cols="20%h,35%,45%",options="header"] |======================================== | Dim, Arrayed, MS | Image parameters | View parameters | 1D, 0, 0 | imageType = IMAGE_TYPE_1D + width >= 1 + height = 1 + depth = 1 + arrayLayers >= 1 + samples = 1 | viewType = VIEW_TYPE_1D + baseArrayLayer >= 0 + arrayLayers = 1 | 1D, 1, 0 | imageType = IMAGE_TYPE_1D + width >= 1 + height = 1 + depth = 1 + arrayLayers >= 1 + samples = 1 | viewType = VIEW_TYPE_1D_ARRAY + baseArrayLayer >= 0 + arrayLayers >= 1 | 2D, 0, 0 | imageType = IMAGE_TYPE_2D + width >= 1 + height >= 1 + depth = 1 + arrayLayers >= 1 + samples = 1 | viewType = VIEW_TYPE_2D + baseArrayLayer >= 0 + arrayLayers = 1 | 2D, 1, 0 | imageType = IMAGE_TYPE_2D + width >= 1 + height >= 1 + depth = 1 + arrayLayers >= 1 + samples = 1 | viewType = VIEW_TYPE_2D_ARRAY + baseArrayLayer >= 0 + arrayLayers >= 1 | 2D, 0, 1 | imageType = IMAGE_TYPE_2D + width >= 1 + height >= 1 + depth = 1 + arrayLayers >= 1 + samples > 1 | viewType = VIEW_TYPE_2D + baseArrayLayer >= 0 + arrayLayers = 1 | 2D, 1, 1 | imageType = IMAGE_TYPE_2D + width >= 1 + height >= 1 + depth = 1 + arrayLayers >= 1 + samples > 1 | viewType = VIEW_TYPE_2D_ARRAY + baseArrayLayer >= 0 + arrayLayers >= 1 | CUBE, 0, 0 | imageType = IMAGE_TYPE_2D + width >= 1 + height = width + depth = 1 + arrayLayers >= 6 + samples = 1 + flags include ename:VK_IMAGE_CREATE_CUBE_COMPATIBLE_BIT | viewType = VIEW_TYPE_CUBE + baseArrayLayer >= 0 + arrayLayers = 6 | CUBE, 1, 0 | imageType = IMAGE_TYPE_2D + width >= 1 + height = width + depth = 1 + arrayLayers >= 6×N + samples = 1 + flags include ename:VK_IMAGE_CREATE_CUBE_COMPATIBLE_BIT | viewType = VIEW_TYPE_CUBE_ARRAY + baseArrayLayer >= 0 + arrayLayers = 6×N | 3D, 0, 0 | imageType = IMAGE_TYPE_3D + width >= 1 + height >= 1 + depth >= 1 + arrayLayers = 1 + samples = 1 | viewType = VIEW_TYPE_3D + baseArrayLayer = 0 + arrayLayers = 1 |======================================== The pname:subresourceRange member is of type sname:VkImageSubresourceRange and is defined as: include::../structs/VkImageSubresourceRange.txt[] * pname:aspectMask is a bitmask indicating which aspect(s) of the image are included in the view. See elink:VkImageAspectFlagBits. * pname:baseMipLevel is the first mipmap level accessible to the view. * pname:levelCount is the number of mipmap levels (starting from pname:baseMipLevel) accessible to the view. * pname:baseArrayLayer is the first array layer accessible to the view. * pname:layerCount is the number of array layers (starting from pname:baseArrayLayer) accessible to the view. include::../validity/structs/VkImageSubresourceRange.txt[] The number of mip-map levels and array layers must: be a subset of the subresources in the image. If an application wants to use all mip-levels or layers in an image after the pname:baseMipLevel or pname:baseArrayLayer, it can: set pname:levelCount and pname:layerCount to the special values ename:VK_REMAINING_MIP_LEVELS and ename:VK_REMAINING_ARRAY_LAYERS without knowing the exact number of mip-levels or layers. For cube and cube array image views, the layers of the image view starting at pname:baseArrayLayer correspond to faces in the order +X, -X, +Y, -Y, +Z, -Z. For cube arrays, each set of six sequential layers is a single cube, so the number of cube maps in a cube map array view is _pname:layerCount / 6_, and image array layer _pname:baseArrayLayer + i_ is face index _i mod 6_ of cube _i / 6_. If the number of layers in the view, whether set explicitly in pname:layerCount or implied by ename:VK_REMAINING_ARRAY_LAYERS, is not a multiple of 6, behavior when indexing the last cube is undefined. pname:aspectMask is a bitmask indicating the format being used. Bits which may: be set include: include::../enums/VkImageAspectFlagBits.txt[] The mask must: be only ename:VK_IMAGE_ASPECT_COLOR_BIT, ename:VK_IMAGE_ASPECT_DEPTH_BIT or ename:VK_IMAGE_ASPECT_STENCIL_BIT if pname:format is a color, depth-only or stencil-only format, respectively. If using a depth/stencil format with both depth and stencil components, pname:aspectMask must: include at least one of ename:VK_IMAGE_ASPECT_DEPTH_BIT and ename:VK_IMAGE_ASPECT_STENCIL_BIT, and can: include both. When using an imageView of a depth/stencil image to populate a descriptor set (e.g. for sampling in the shader, or for use as an input attachment), the pname:aspectMask must: only include one bit and selects whether the imageView is used for depth reads (i.e. using a floating-point sampler or input attachment in the shader) or stencil reads (i.e. using an unsigned integer sampler or input attachment in the shader). When an imageView of a depth/stencil image is used as a depth/stencil framebuffer attachment, the pname:aspectMask is ignored and both depth and stencil subresources are used. The pname:components member is defined as follows: include::../structs/VkComponentMapping.txt[] and describes a remapping from components of the image to components of the vector returned by shader image instructions. This remapping must: be identity for storage image descriptors, input attachment descriptors, and framebuffer attachments. The pname:r, pname:g, pname:b, and pname:a members of pname:components are the values placed in the corresponding components of the output vector: include::../enums/VkComponentSwizzle.txt[] * ename:VK_COMPONENT_SWIZZLE_IDENTITY: the component is set to the identity swizzle. * ename:VK_COMPONENT_SWIZZLE_ZERO: the component is set to zero. * ename:VK_COMPONENT_SWIZZLE_ONE: the component is set to either 1 or 1.0 depending on whether the type of the image view format is integer or floating-point respectively, as determined by the <> section for each elink:VkFormat. * ename:VK_COMPONENT_SWIZZLE_R: the component is set to the value of the R component of the image. * ename:VK_COMPONENT_SWIZZLE_G: the component is set to the value of the G component of the image. * ename:VK_COMPONENT_SWIZZLE_B: the component is set to the value of the B component of the image. * ename:VK_COMPONENT_SWIZZLE_A: the component is set to the value of the A component of the image. include::../validity/structs/VkComponentMapping.txt[] Setting the identity swizzle on a component is equivalent to setting the identity mapping on that component. That is: [[resources-image-views-identity-mappings]] .Component Mappings Equivalent To ename:VK_COMPONENT_SWIZZLE_IDENTITY [options="header"] |==== | Component | Identity Mapping | pname:components.r | ename:VK_COMPONENT_SWIZZLE_R | pname:components.g | ename:VK_COMPONENT_SWIZZLE_G | pname:components.b | ename:VK_COMPONENT_SWIZZLE_B | pname:components.a | ename:VK_COMPONENT_SWIZZLE_A |==== To destroy an image view, call: include::../protos/vkDestroyImageView.txt[] * pname:device is the logical device that destroys the image view. * pname:imageView is the image view to destroy. * pname:pAllocator controls host memory allocation as described in the <> chapter. include::../validity/protos/vkDestroyImageView.txt[] [[resources-association]] == Resource Memory Association Resources are initially created as _virtual allocations_ with no backing memory. Device memory is allocated separately (see <>) and then associated with the resource. This association is done differently for sparse and non-sparse resources. Resources created with any of the sparse creation flags are considered sparse resources. Resources created without these flags are non-sparse. The details on resource memory association for sparse resources is described in <>. Non-sparse resources must: be bound completely and contiguously to a single slink:VkDeviceMemory object before the resource is passed as a parameter to any of the following operations: * creating image or buffer views * updating descriptor sets * recording commands in a command buffer Once bound, the memory binding is immutable for the lifetime of the resource. To determine the memory requirements for a non-sparse buffer resource, call: include::../protos/vkGetBufferMemoryRequirements.txt[] * pname:device is the logical device that owns the buffer. * pname:buffer is the buffer to query. * pname:pMemoryRequirements points to an instance of the slink:VkMemoryRequirements structure in which the memory requirements of the buffer object are returned. include::../validity/protos/vkGetBufferMemoryRequirements.txt[] To determine the memory requirements for a non-sparse image resource, call: include::../protos/vkGetImageMemoryRequirements.txt[] * pname:device is the logical device that owns the image. * pname:image is the image to query. * pname:pMemoryRequirements points to an instance of the slink:VkMemoryRequirements structure in which the memory requirements of the image object are returned. include::../validity/protos/vkGetImageMemoryRequirements.txt[] The sname:VkMemoryRequirements structure returned by flink:vkGetBufferMemoryRequirements and flink:vkGetImageMemoryRequirements is defined as follows: include::../structs/VkMemoryRequirements.txt[] * pname:size is the size, in bytes, of the memory allocation required: for the resource. * pname:alignment is the alignment, in bytes, of the offset within the allocation required: for the resource. * pname:memoryTypeBits is a bitfield and contains one bit set for every supported memory type for the resource. Bit `i` is set if and only if the memory type `i` in the sname:VkPhysicalDeviceMemoryProperties structure for the physical device is supported for the resource. include::../validity/structs/VkMemoryRequirements.txt[] The implementation guarantees certain properties about the memory requirements returned by flink:vkGetBufferMemoryRequirements and flink:vkGetImageMemoryRequirements: * The pname:memoryTypeBits member always contains at least one bit set. * If pname:buffer is a sname:VkBuffer, or if pname:image is a sname:VkImage that was created with a ename:VK_IMAGE_TILING_LINEAR value in the pname:tiling member of the sname:VkImageCreateInfo structure passed to fname:vkCreateImage, then the pname:memoryTypeBits member always contains at least one bit set corresponding to a sname:VkMemoryType with a pname:propertyFlags that has both the ename:VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT bit and the ename:VK_MEMORY_PROPERTY_HOST_COHERENT_BIT bit set. In other words, mappable coherent memory can: always be attached to these objects. * The value of the pname:memoryTypeBits member is identical for all sname:VkBuffer objects created with the same value for the pname:flags and pname:usage members in the sname:VkBufferCreateInfo structure passed to fname:vkCreateBuffer. Further, if code:usage1 and code:usage2 of type elink:VkBufferUsageFlags are such that code:usage2 contains a subset of the bits set in code:usage1 and they have the same value of pname:flags, then the bits set in the value of pname:memoryTypeBits returned for code:usage1 must: be a subset of the bits set in the value of pname:memoryTypeBits returned for code:usage2, for all values of pname:flags. * The value of the pname:alignment member is identical for all sname:VkBuffer objects created with the same combination of values for the pname:usage and pname:flags members in the sname:VkBufferCreateInfo structure passed to fname:vkCreateBuffer. * The value of the pname:memoryTypeBits member is identical for all sname:VkImage objects created with the same combination of values for the pname:tiling member and the ename:VK_IMAGE_CREATE_SPARSE_BINDING_BIT bit of the pname:flags member and the ename:VK_IMAGE_USAGE_TRANSIENT_ATTACHMENT_BIT of the pname:usage member in the sname:VkImageCreateInfo structure passed to fname:vkCreateImage. * The pname:memoryTypeBits member mustnot: refer to a sname:VkMemoryType with a pname:propertyFlags that has the ename:VK_MEMORY_PROPERTY_LAZILY_ALLOCATED_BIT bit set if the sname:VkImage does not have ename:VK_IMAGE_USAGE_TRANSIENT_ATTACHMENT_BIT bit set in the pname:usage member of the sname:VkImageCreateInfo structure passed to fname:vkCreateImage. To attach memory to a buffer object, call: include::../protos/vkBindBufferMemory.txt[] * pname:device is the logical device that owns the buffer and memory. * pname:buffer is the buffer. * pname:memory is a sname:VkDeviceMemory object describing the device memory to attach. * pname:memoryOffset is the start offset of the region of pname:memory which is to be bound to the buffer. The number of bytes returned in the sname:VkMemoryRequirements::pname:size member in pname:memory, starting from pname:memoryOffset bytes, will be bound to the specified buffer. include::../validity/protos/vkBindBufferMemory.txt[] To attach memory to a image object, call: include::../protos/vkBindImageMemory.txt[] * pname:device is the logical device that owns the image and memory. * pname:image is the image. * pname:memory is the a sname:VkDeviceMemory object describing the device memory to attach. * pname:memoryOffset is the start offset of the region of pname:memory which is to be bound to the image. The number of bytes returned in the sname:VkMemoryRequirements::pname:size member in pname:memory, starting from pname:memoryOffset bytes, will be bound to the specified image. include::../validity/protos/vkBindImageMemory.txt[] [[resources-bufferimagegranularity,Buffer-Image Granularity]] .Buffer-Image Granularity There is an implementation-dependent limit, pname:bufferImageGranularity, which specifies a page-like granularity at which buffer, linear image and optimal image resources must be placed in adjacent memory locations for simultaneous usage. Two resources which do not satisfy this granularity requirement are said to <>. Linear image resource are images created with ename:VK_IMAGE_TILING_LINEAR and optimal linear resources are those created with ename:VK_IMAGE_TILING_OPTIMAL. pname:bufferImageGranularity is specified in bytes, and must: be a power of two. Implementations which do not require such an additional granularity may: report a value of one. Given resourceA at the lower memory offset and resourceB at the higher memory offset, where one of the resources is a buffer and the other is an image, and the following: resourceA.end = resourceA.memoryOffset + resourceA.size - 1 resourceA.endPage = resourceA.end & ~(bufferImageGranularity-1) resourceB.start = resourceB.memoryOffset resourceB.startPage = resourceB.start & ~(bufferImageGranularity-1) The following property must: hold: resourceA.endPage < resourceB.startPage That is, the end of the first resource (A) and the beginning of the second resource (B) must: be on separate ``pages'' of size pname:bufferImageGranularity. pname:bufferImageGranularity may: be different than the physical page size of the memory heap. This restriction is only needed for adjacent image and buffer memory locations which will be used simultaneously. Adjacent buffers' or adjacent images' memory ranges can: be closer than pname:bufferImageGranularity, provided they meet the pname:alignment requirement for the objects in question. Sparse memory block sizes and sparse image and buffer memory alignments must: all be multiples of the pname:bufferImageGranularity. Therefore, memory bound to sparse resources naturally satisfies the pname:bufferImageGranularity. [[resources-sharing]] == Resource Sharing Mode Buffer and image objects are created with a _sharing mode_ controlling how they can: be accessed from queues. The supported sharing modes are: include::../enums/VkSharingMode.txt[] * ename:VK_SHARING_MODE_EXCLUSIVE specifies that access to any range or subresource of the object will be exclusive to a single queue family at a time. * ename:VK_SHARING_MODE_CONCURRENT specifies that concurrent access to any range or subresource of the object from multiple queue families is supported. [NOTE] .Note ==== ename:VK_SHARING_MODE_CONCURRENT may: result in lower performance access to the buffer or image than ename:VK_SHARING_MODE_EXCLUSIVE. ==== Ranges of buffers and subresources of image objects created using ename:VK_SHARING_MODE_EXCLUSIVE must: only be accessed by queues in the same queue family at any given time. In order for a different queue family to be able to interpret the memory contents of a range or subresource, the application must: transfer exclusive ownership of the range or subresource between the source and destination queue families with the following sequence of operations: 1. Release exclusive ownership from the source queue family to the destination queue family. 2. Use semaphores to ensure proper execution control for the ownership transfer. 3. Acquire exclusive ownership for the destination queue family from the source queue family. To release exclusive ownership of a range of a buffer or subresource of an image object, the application must: execute a buffer or image memory barrier, respectively (see slink:VkBufferMemoryBarrier and slink:VkImageMemoryBarrier) on a queue from the source queue family. The pname:srcQueueFamilyIndex parameter of the barrier must: be set to the source queue family index, and the pname:dstQueueFamilyIndex parameter to the destination queue family index. To acquire exclusive ownership, the application must: execute the same buffer or image memory barrier on a queue from the destination queue family. Upon creation, resources using ename:VK_SHARING_MODE_EXCLUSIVE are not owned by any queue family. A buffer or image memory barrier is not required to acquire ownership when no queue family owns the resource - it is implicitly acquired upon first use within a queue. However, images still require a <> from ename:VK_IMAGE_LAYOUT_UNDEFINED or ename:VK_IMAGE_LAYOUT_PREINITIALIZED before being used on the first queue. This layout transition can: either be accomplished by an image memory barrier or by use in a render pass instance. Once a queue family has used a range or subresource of an ename:VK_SHARING_MODE_EXCLUSIVE resource, its contents are undefined to other queue families unless ownership is transferred. The contents may: also become undefined for other reasons, e.g. as a result of writes to an image subresource that aliases the same memory. A queue family can: take ownership of a range or subresource without an ownership transfer in the same way as for a resource that was just created, however doing so means any contents written by other queue families or via incompatible aliases are undefined. [[resources-memory-aliasing]] == Memory Aliasing A range of a sname:VkDeviceMemory allocation is _aliased_ if it is bound to multiple resources simultaneously, via flink:vkBindImageMemory, flink:vkBindBufferMemory, or via <>. A memory range aliased between two images or two buffers is defined to be the intersection of the memory ranges bound to the two resources. A memory range aliased between an image and a buffer is defined to be the intersection of the memory ranges bound to the two resources, where each range is first bloated to be aligned to the pname:bufferImageGranularity. Applications can: alias memory, but use of multiple aliases is subject to several constraints. [NOTE] .Note ==== Memory aliasing can: be useful to reduce the total device memory footprint of an application, if some large resources are used for disjoint periods of time. ==== When an opaque, non-ename:VK_IMAGE_CREATE_SPARSE_RESIDENCY_BIT image is bound to an aliased range, all subresources of the image _overlap_ the range. When a linear image is bound to an aliased range, the subresources that (according to the image's advertised layout) include bytes from the aliased range overlap the range. When a ename:VK_IMAGE_CREATE_SPARSE_RESIDENCY_BIT image has blocks bound to an aliased range, only subresources including those blocks overlap the range, and when the memory bound to the image's miptail overlaps an aliased range all subresources in the miptail overlap the range. Buffers, and linear image subresources in either the ename:VK_IMAGE_LAYOUT_PREINITIALIZED or ename:VK_IMAGE_LAYOUT_GENERAL layouts, are _host-accessible subresources_. That is, the host has a well-defined addressing scheme to interpret the contents, and thus the layout of the data in memory can be consistently interpreted across aliases if each of those aliases is a host-accessible subresource. Opaque images and linear image subresources in other layouts are not host-accessible. If two aliases are both host-accessible, then they interpret the contents of the memory in consistent ways, and data written to one alias can: be read by the other alias. If either of two aliases is not host-accessible, then the aliases interpret the contents of the memory differently, and writes via one alias make the contents of memory partially or completely undefined to the other alias. If the first alias is a host-accessible subresource, then the bytes affected are those written by the memory operations according to its addressing scheme. If the first alias is not host-accessible, then the bytes affected are those overlapped by the image subresources that were written. If the second alias is a host-accessible subresource, the affected bytes become undefined. If the second alias is a not host-accessible, all sparse blocks (for sparse residency images) or all subresources (for non-sparse residency images) that overlap the affected bytes become undefined. If any subresources are made undefined due to writes to an alias, then each of those subresources must: have its layout transitioned from ename:VK_IMAGE_LAYOUT_UNDEFINED to a valid layout before it is used, or from ename:VK_IMAGE_LAYOUT_PREINITIALIZED if the memory has been written by the host. If any blocks of a sparse image have been made undefined, then only the subresources containing them must: be transitioned. Use of an overlapping range by two aliases must: be separated by a memory dependency using the appropriate access types if at least one of those uses performs writes, whether the aliases interpret memory consistently or not. If buffer or image memory barriers are used, the scope of the barrier must: contain the entire range and/or set of subresources that overlap. If two aliasing image views are used in the same framebuffer, then the render pass must: declare the attachments using the <>, and follow the other rules listed in that section. Access to resources which alias memory from shaders using variables decorated with code:Coherent are not automatically coherent with each other. [NOTE] .Note ==== Memory recycled via an application suballocator (i.e. without freeing and reallocating the memory objects) is not substantially different from memory aliasing. However, a suballocator usually waits on a fence before recycling a region of memory, and signalling a fence involves enough <> that the above requirements are all satisfied. ====