// Copyright (c) 2015-2016 The Khronos Group Inc. // Copyright notice at https://www.khronos.org/registry/speccopyright.html [[resources]] = Resource Creation Vulkan 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 // refBegin VkBuffer Opaque handle to a buffer object Buffers represent linear arrays of data which are used for various purposes by binding them to a graphics or compute pipeline via descriptor sets or via certain commands, or by directly specifying them as parameters to certain commands. Buffers are represented by sname:VkBuffer handles: include::../api/handles/VkBuffer.txt[] // refEnd VkBuffer // refBegin vkCreateBuffer Create a new buffer object To create buffers, call: include::../api/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[] // refBegin VkBufferCreateInfo Structure specifying the parameters of a newly created buffer object The sname:VkBufferCreateInfo structure is defined as: include::../api/structs/VkBufferCreateInfo.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:flags is a bitmask 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 bitmask 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). Bits which can: be set in pname:usage are: // refBegin VkBufferUsageFlagBits Bitmask specifying allowed usage of a buffer include::../api/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 can: be set in pname:flags are: // refBegin VkBufferCreateFlagBits Bitmask specifying additional parameters of a buffer include::../api/enums/VkBufferCreateFlagBits.txt[] These bits 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. Buffers created with this flag must: also be created with the ename:VK_BUFFER_CREATE_SPARSE_BINDING_BIT flag. * 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). Buffers created with this flag must: also be created with the ename:VK_BUFFER_CREATE_SPARSE_BINDING_BIT flag. See <> and <> for details of the sparse memory features supported on a device. include::../validity/structs/VkBufferCreateInfo.txt[] ifdef::VK_NV_dedicated_allocation[] // refBegin VkDedicatedAllocationBufferCreateInfoNV Specify that a buffer is bound to a dedicated memory resource If the pname:pNext list includes a sname:VkDedicatedAllocationBufferCreateInfoNV structure, then that structure includes an enable controlling whether the buffer will have a dedicated memory allocation bound to it. The sname:VkDedicatedAllocationBufferCreateInfoNV structure is defined as: include::../api/structs/VkDedicatedAllocationBufferCreateInfoNV.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:dedicatedAllocation indicates whether the buffer will have a dedicated allocation bound to it. include::../validity/structs/VkDedicatedAllocationBufferCreateInfoNV.txt[] endif::VK_NV_dedicated_allocation[] // refBegin vkDestroyBuffer Destroy a buffer object To destroy a buffer, call: include::../api/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 // refBegin VkBufferView Opaque handle to a buffer view object 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 Buffer views are represented by sname:VkBufferView handles: include::../api/handles/VkBufferView.txt[] // refEnd VkBufferView // refBegin vkCreateBufferView Create a new buffer view object To create a buffer view, call: include::../api/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[] // refBegin VkBufferViewCreateInfo Structure specifying parameters of a newly created buffer view The sname:VkBufferViewCreateInfo structure is defined as: include::../api/structs/VkBufferViewCreateInfo.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: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[] // refBegin vkDestroyBufferView Destroy a buffer view object To destroy a buffer view, call: include::../api/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 // refBegin VkImage Opaque handle to a image object Images represent multidimensional - up to 3 - arrays of data which can: be used for various purposes (e.g. attachments, textures), by binding them to a graphics or compute pipeline via descriptor sets, or by directly specifying them as parameters to certain commands. Images are represented by sname:VkImage handles: include::../api/handles/VkImage.txt[] // refEnd VkImage // refBegin vkCreateImage Create a new image object To create images, call: include::../api/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[] // refBegin VkImageCreateInfo Structure specifying the parameters of a newly created image object The sname:VkImageCreateInfo structure is defined as: include::../api/structs/VkImageCreateInfo.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:flags is a bitmask describing additional parameters of the image. See elink:VkImageCreateFlagBits below for a description of the supported bits. * pname:imageType is a elink:VkImageType specifying the basic dimensionality of the image, as described below. 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 a elink:VkImageTiling specifying the tiling arrangement of the data elements in memory, as described below. * pname:usage is a bitmask 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 image subresources of the image. See <>. pname:initialLayout must: be ename:VK_IMAGE_LAYOUT_UNDEFINED or ename:VK_IMAGE_LAYOUT_PREINITIALIZED. 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 may: not 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. include::../validity/structs/VkImageCreateInfo.txt[] ifdef::VK_NV_dedicated_allocation[] // refBegin VkDedicatedAllocationImageCreateInfoNV Specify that an image is bound to a dedicated memory resource If the pname:pNext list includes a sname:VkDedicatedAllocationImageCreateInfoNV structure, then that structure includes an enable controlling whether the image will have a dedicated memory allocation bound to it. The sname:VkDedicatedAllocationImageCreateInfoNV structure is defined as: include::../api/structs/VkDedicatedAllocationImageCreateInfoNV.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:dedicatedAllocation indicates whether the image will have a dedicated allocation bound to it. [NOTE] .Note ==== Using a dedicated allocation for color and depth/stencil attachments or other large images may: improve performance on some devices. ==== include::../validity/structs/VkDedicatedAllocationImageCreateInfoNV.txt[] endif::VK_NV_dedicated_allocation[] ifdef::VK_NV_external_memory[] // refBegin VkExternalMemoryImageCreateInfoNV Specify that an image may be backed by external memory If the pname:pNext list includes a sname:VkExternalMemoryImageCreateInfoNV structure, then that structure defines a set of external memory handle types that may: be used as backing store for the image. The sname:VkExternalMemoryImageCreateInfoNV structure is defined as: include::../api/structs/VkExternalMemoryImageCreateInfoNV.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:handleTypes is a bitmask of elink:VkExternalMemoryHandleTypeFlagBitsNV specifying one or more external memory handle types. The types must: all be compatible with each other and the other image creation parameters, as reported by flink:vkGetPhysicalDeviceExternalImageFormatPropertiesNV. include::../validity/structs/VkExternalMemoryImageCreateInfoNV.txt[] endif::VK_NV_external_memory[] // refBegin VkImageUsageFlagBits Bitmask specifying intended usage of an image The intended usage of an image is specified by the bitmask slink:VkImageCreateInfo::pname:usage. Bits which can: be set include: include::../api/enums/VkImageUsageFlagBits.txt[] These bits 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). This bit can: be set for any image that can: be used to create a sname:VkImageView suitable for use as a color, resolve, depth/stencil, or input attachment. * 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. // refEnd VkImageUsageFlagBits // refBegin VkImageCreateFlagBits Bitmask specifying additional parameters of an image Additional parameters of an image are specified by slink:VkImageCreateInfo::pname:flags. Bits which can: be set include: include::../api/enums/VkImageCreateFlagBits.txt[] These bits 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. Images created with this flag must: also be created with the ename:VK_IMAGE_CREATE_SPARSE_BINDING_BIT flag. * 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). Images created with this flag must: also be created with the ename:VK_IMAGE_CREATE_SPARSE_BINDING_BIT flag * ename:VK_IMAGE_CREATE_MUTABLE_FORMAT_BIT indicates that the image can: be used to create a sname: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 sname:VkImageView of type ename:VK_IMAGE_VIEW_TYPE_CUBE or ename:VK_IMAGE_VIEW_TYPE_CUBE_ARRAY. If any of the bits ename:VK_IMAGE_CREATE_SPARSE_BINDING_BIT, ename:VK_IMAGE_CREATE_SPARSE_RESIDENCY_BIT, or ename:VK_IMAGE_CREATE_SPARSE_ALIASED_BIT are set, ename:VK_IMAGE_USAGE_TRANSIENT_ATTACHMENT_BIT must: not also be set. See <> and <> for more details. // refEnd VkImageCreateFlagBits // refBegin VkImageType Specifies the type of an image object The basic dimensionality of an image is specified by slink:VkImageCreateInfo::pname:imageType, which must: be one of the values include::../api/enums/VkImageType.txt[] These values specify one-, two-, or three-dimensional images, respectively. // refEnd VkImageType // refBegin VkImageTiling Specifies the tiling arrangement of data in an image The tiling arrangement of data elements in an image is specified by slink:VkImageCreateInfo::pname:tiling, which must: be one of the values include::../api/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). // refEnd VkImageTiling // refBegin vkGetImageSubresourceLayout Retrieve information about an image subresource To query the host access layout of an image subresource, for an image created with linear tiling, call: include::../api/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 image subresource. * pname:pLayout points to a slink:VkSubresourceLayout structure in which the layout is returned. flink:vkGetImageSubresourceLayout is invariant for the lifetime of a single image. include::../validity/protos/vkGetImageSubresourceLayout.txt[] // refBegin VkImageSubresource Structure specifying a image subresource The sname:VkImageSubresource structure is defined as: include::../api/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[] // refBegin VkSubresourceLayout Structure specifying subresource layout Information about the layout of the image subresource is returned in a sname:VkSubresourceLayout structure: include::../api/structs/VkSubresourceLayout.txt[] * pname:offset is the byte offset from the start of the image where the image subresource begins. * pname:size is the size in bytes of the image subresource. pname:size includes any extra memory that is required based on 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. For images created with linear tiling, pname:rowPitch, pname:arrayPitch and pname:depthPitch describe the layout of the image 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 image 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 texel blocks in adjacent rows. pname:arrayPitch is the number of bytes between compressed texel blocks in adjacent array layers. pname:depthPitch is the number of bytes between compressed texel blocks in adjacent slices of a 3D image. [source,c] --------------------------------------------------- // (x,y,z,layer) are in compressed texel block coordinates address(x,y,z,layer) = layer*arrayPitch + z*depthPitch + y*rowPitch + x*compressedTexelBlockByteSize + 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:aspectMask 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 image 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. include::../validity/structs/VkSubresourceLayout.txt[] // refBegin vkDestroyImage Destroy an image object To destroy an image, call: include::../api/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 image subresource. Each layout has limitations on what kinds of operations are supported for image 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-image subresource, and separate image subresources of the same image can: be in different layouts at the same time with one exception - depth and stencil aspects of a given image 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 image 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 image 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 preinitialized 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 image 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 image subresources of those images which are currently in either the ename:VK_IMAGE_LAYOUT_PREINITIALIZED or ename:VK_IMAGE_LAYOUT_GENERAL layout. Calling flink:vkGetImageSubresourceLayout for a linear image returns a subresource layout mapping that is valid for either of those image layouts. // refBegin VkImageLayout Layout of image and image subresources The set of image layouts consists of: include::../api/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 the pname:initialLayout member of sname:VkImageCreateInfo or sname:VkAttachmentDescription, 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 the pname:initialLayout member of sname:VkImageCreateInfo or sname:VkAttachmentDescription, 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 image 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 image 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 image subresources of images created with 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 image 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 image 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 image subresources of images created with the ename:VK_IMAGE_USAGE_TRANSFER_DST_BIT usage bit enabled. ifdef::VK_KHR_swapchain[] * ename:VK_IMAGE_LAYOUT_PRESENT_SRC_KHR: must: only be used for presenting a swapchain image for display. A swapchain's image must: be transitioned to this layout before calling flink:vkQueuePresentKHR, and must: be transitioned away from this layout after calling flink:vkAcquireNextImageKHR. endif::VK_KHR_swapchain[] 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 image subresource's lifetime. This means that when performing a layout transition on the image subresource, the old layout value must: either equal the current layout of the image subresource (at the time the transition executes), or else be ename:VK_IMAGE_LAYOUT_UNDEFINED (implying that the contents of the image subresource need not be preserved). The new layout used in a transition must: not be ename:VK_IMAGE_LAYOUT_UNDEFINED or ename:VK_IMAGE_LAYOUT_PREINITIALIZED. // refEnd VkImageLayout [[resources-image-views]] == Image Views // refBegin VkImageView Opaque handle to a image view object 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. Image views are represented by sname:VkImageView handles: include::../api/handles/VkImageView.txt[] // refEnd VkImageView // refBegin VkImageViewType Image view types The types of image views that can: be created are: include::../api/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. // refEnd VkImageViewType // refBegin vkCreateImageView Create an image view from an existing image To create an image view, call: include::../api/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[] // refBegin VkImageViewCreateInfo Structure specifying parameters of a newly created image view The sname:VkImageViewCreateInfo structure is defined as: include::../api/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 is a slink:VkImageSubresourceRange selecting the set of mipmap levels and array layers to be accessible to the view. 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 = ename:VK_IMAGE_TYPE_1D + width >= 1 + height = 1 + depth = 1 + arrayLayers >= 1 + samples = 1 | viewType = ename:VK_VIEW_TYPE_1D + baseArrayLayer >= 0 + layerCount = 1 | 1D, 1, 0 | imageType = ename:VK_IMAGE_TYPE_1D + width >= 1 + height = 1 + depth = 1 + arrayLayers >= 1 + samples = 1 | viewType = ename:VK_VIEW_TYPE_1D_ARRAY + baseArrayLayer >= 0 + layerCount >= 1 | 2D, 0, 0 | imageType = ename:VK_IMAGE_TYPE_2D + width >= 1 + height >= 1 + depth = 1 + arrayLayers >= 1 + samples = 1 | viewType = ename:VK_VIEW_TYPE_2D + baseArrayLayer >= 0 + layerCount = 1 | 2D, 1, 0 | imageType = ename:VK_IMAGE_TYPE_2D + width >= 1 + height >= 1 + depth = 1 + arrayLayers >= 1 + samples = 1 | viewType = ename:VK_VIEW_TYPE_2D_ARRAY + baseArrayLayer >= 0 + layerCount >= 1 | 2D, 0, 1 | imageType = ename:VK_IMAGE_TYPE_2D + width >= 1 + height >= 1 + depth = 1 + arrayLayers >= 1 + samples > 1 | viewType = ename:VK_VIEW_TYPE_2D + baseArrayLayer >= 0 + layerCount = 1 | 2D, 1, 1 | imageType = ename:VK_IMAGE_TYPE_2D + width >= 1 + height >= 1 + depth = 1 + arrayLayers >= 1 + samples > 1 | viewType = ename:VK_VIEW_TYPE_2D_ARRAY + baseArrayLayer >= 0 + layerCount >= 1 | CUBE, 0, 0 | imageType = ename:VK_IMAGE_TYPE_2D + width >= 1 + height = width + depth = 1 + arrayLayers >= 6 + samples = 1 + flags include ename:VK_IMAGE_CREATE_CUBE_COMPATIBLE_BIT | viewType = ename:VK_VIEW_TYPE_CUBE + baseArrayLayer >= 0 + layerCount = 6 | CUBE, 1, 0 | imageType = ename:VK_IMAGE_TYPE_2D + width >= 1 + height = width + depth = 1 + N >= 1 + arrayLayers >= latexmath:[$6 \times N$] + samples = 1 + flags include ename:VK_IMAGE_CREATE_CUBE_COMPATIBLE_BIT | viewType = ename:VK_VIEW_TYPE_CUBE_ARRAY + baseArrayLayer >= 0 + N >= 1 + layerCount = latexmath:[$6 \times N$] | 3D, 0, 0 | imageType = ename:VK_IMAGE_TYPE_3D + width >= 1 + height >= 1 + depth >= 1 + arrayLayers = 1 + samples = 1 | viewType = ename:VK_VIEW_TYPE_3D + baseArrayLayer = 0 + layerCount = 1 |==== include::../validity/structs/VkImageViewCreateInfo.txt[] // refBegin VkImageSubresourceRange Structure specifying a image subresource range The sname:VkImageSubresourceRange structure is defined as: include::../api/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. The number of mipmap levels and array layers must: be a subset of the image 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: // refBegin VkImageAspectFlagBits Bitmask specifying which aspects of an image are included in a view include::../api/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 image subresources are used. The pname:components member is of type slink:VkComponentMapping, 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. include::../validity/structs/VkImageSubresourceRange.txt[] // refBegin VkComponentMapping Structure specifying a color component mapping The sname:VkComponentMapping structure is defined as: include::../api/structs/VkComponentMapping.txt[] * pname:r determines the component value placed in the R component of the output vector. * pname:g determines the component value placed in the G component of the output vector. * pname:b determines the component value placed in the B component of the output vector. * pname:a determines the component value placed in the A component of the output vector. Each of pname:r, pname:g, pname:b, and pname:a is one of the values: // refBegin VkComponentSwizzle Specify how a component is swizzled include::../api/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. 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 |==== include::../validity/structs/VkComponentMapping.txt[] // refBegin vkDestroyImageView Destroy an image view object To destroy an image view, call: include::../api/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 sname: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. // refBegin vkGetBufferMemoryRequirements Returns the memory requirements for specified Vulkan object To determine the memory requirements for a buffer resource, call: include::../api/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[] // refBegin vkGetImageMemoryRequirements Returns the memory requirements for specified Vulkan object To determine the memory requirements for an image resource, call: include::../api/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[] // refBegin VkMemoryRequirements Structure specifying memory requirements The sname:VkMemoryRequirements structure is defined as: include::../api/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 bitmask 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 pname:memoryTypeBits member always contains at least one bit set corresponding to a sname:VkMemoryType with a pname:propertyFlags that has the ename:VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT bit set. * 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 the bits set in code:usage2 are a subset of the bits set in code:usage1, and they have the same pname:flags, then the bits set in pname:memoryTypeBits returned for code:usage1 must: be a subset of the bits set in pname:memoryTypeBits returned for code:usage2, for all values of pname:flags. * 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 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. * If the memory requirements are for a sname:VkImage, the pname:memoryTypeBits member must: not refer to a sname:VkMemoryType with a pname:propertyFlags that has the ename:VK_MEMORY_PROPERTY_LAZILY_ALLOCATED_BIT bit set if the flink:vkGetImageMemoryRequirements::pname:image did 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. * If the memory requirements are for a sname:VkBuffer, the pname:memoryTypeBits member must: not refer to a sname:VkMemoryType with a pname:propertyFlags that has the ename:VK_MEMORY_PROPERTY_LAZILY_ALLOCATED_BIT bit set. + -- [NOTE] .Note ==== The implication of this requirement is that lazily allocated memory is disallowed for buffers in all cases. ==== -- // refBegin vkBindBufferMemory Bind device memory to a buffer object To attach memory to a buffer object, call: include::../api/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[] // refBegin vkBindImageMemory Bind device memory to an image object To attach memory to an image object, call: include::../api/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 to avoid aliasing. 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 image 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. [NOTE] .Note ==== pname:bufferImageGranularity is really a granularity between "linear" resources, including buffers and images with linear tiling, vs. "optimal" resources, i.e. images with optimal tiling. It would have been better named "linearOptimalGranularity". ==== Given resourceA at the lower memory offset and resourceB at the higher memory offset in the same sname:VkDeviceMemory object, where one of the resources is a buffer or a linear image and the other is an optimal image, and the following: [source,c] --------------------------------------------------- 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: [source,c] --------------------------------------------------- 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 when a buffer or a linear image is at adjacent memory location with an optimal image and both 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 block size in bytes 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 // refBegin VkSharingMode Buffer and image sharing modes Buffer and image objects are created with a _sharing mode_ controlling how they can: be accessed from queues. The supported sharing modes are: include::../api/enums/VkSharingMode.txt[] * ename:VK_SHARING_MODE_EXCLUSIVE specifies that access to any range or image 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 image 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 image 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 image subresource, the application must: transfer exclusive ownership of the range or image subresource between the source and destination queue families with the following sequence of operations: . Release exclusive ownership from the source queue family to the destination queue family. . Use semaphores to ensure proper execution control for the ownership transfer. . Acquire exclusive ownership for the destination queue family from the source queue family. To release exclusive ownership of a range of a buffer or image 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 image 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 image 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. // refEnd VkSharingMode [[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 two resources where one is a buffer or a linear image, and the other is an optimal image, is defined to be the intersection of the memory ranges bound to the two resources, where each range is first padded 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 image subresources of the image _overlap_ the range. When a linear image is bound to an aliased range, the image 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 sparse image blocks bound to an aliased range, only image subresources including those sparse image blocks overlap the range, and when the memory bound to the image's mip tail overlaps an aliased range all image subresources in the mip tail 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 image blocks (for sparse partially-resident images) or all image subresources (for non-sparse image and fully resident sparse images) that overlap the affected bytes become undefined. If any image subresources are made undefined due to writes to an alias, then each of those image 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 sparse blocks of a sparse image have been made undefined, then only the image 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 image 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 signaling a fence involves sufficient implicit dependencies to satisfy all the above requirements. ====