// Copyright (c) 2015-2017 Khronos Group. This work is licensed under a // Creative Commons Attribution 4.0 International License; see // http://creativecommons.org/licenses/by/4.0/ [[renderpass]] = Render Pass [open,refpage='VkRenderPass',desc='Opaque handle to a render pass object',type='handles'] -- A _render pass_ represents a collection of attachments, subpasses, and dependencies between the subpasses, and describes how the attachments are used over the course of the subpasses. The use of a render pass in a command buffer is a _render pass instance_. Render passes are represented by sname:VkRenderPass handles: include::../api/handles/VkRenderPass.txt[] -- An _attachment description_ describes the properties of an attachment including its format, sample count, and how its contents are treated at the beginning and end of each render pass instance. [[renderpass-subpass]] A _subpass_ represents a phase of rendering that reads and writes a subset of the attachments in a render pass. Rendering commands are recorded into a particular subpass of a render pass instance. A _subpass description_ describes the subset of attachments that is involved in the execution of a subpass. Each subpass can: read from some attachments as _input attachments_, write to some as _color attachments_ or _depth/stencil attachments_, and perform _multisample resolve operations_ to _resolve attachments_. A subpass description can: also include a set of _preserve attachments_, which are attachments that are not read or written by the subpass but whose contents must: be preserved throughout the subpass. A subpass _uses an attachment_ if the attachment is a color, depth/stencil, resolve, or input attachment for that subpass (as determined by the pname:pColorAttachments, pname:pDepthStencilAttachment, pname:pResolveAttachments, and pname:pInputAttachments members of slink:VkSubpassDescription, respectively). A subpass does not use an attachment if that attachment is preserved by the subpass. The _first use of an attachment_ is in the lowest numbered subpass that uses that attachment. Similarly, the _last use of an attachment_ is in the highest numbered subpass that uses that attachment. The subpasses in a render pass all render to the same dimensions, and fragments for pixel (x,y,layer) in one subpass can: only read attachment contents written by previous subpasses at that same (x,y,layer) location. [NOTE] .Note ==== By describing a complete set of subpasses in advance, render passes provide the implementation an opportunity to optimize the storage and transfer of attachment data between subpasses. In practice, this means that subpasses with a simple framebuffer-space dependency may: be merged into a single tiled rendering pass, keeping the attachment data on-chip for the duration of a render pass instance. However, it is also quite common for a render pass to only contain a single subpass. ==== _Subpass dependencies_ describe <> between subpasses. A _subpass dependency chain_ is a sequence of subpass dependencies in a render pass, where the source subpass of each subpass dependency (after the first) equals the destination subpass of the previous dependency. Execution of subpasses may: overlap or execute out of order with regards to other subpasses, unless otherwise enforced by an execution dependency. Each subpass only respects <> for commands recorded in the same subpass, and the flink:vkCmdBeginRenderPass and flink:vkCmdEndRenderPass commands that delimit the render pass - commands within other subpasses are not included. This affects most other <>. A render pass describes the structure of subpasses and attachments independent of any specific image views for the attachments. The specific image views that will be used for the attachments, and their dimensions, are specified in sname:VkFramebuffer objects. Framebuffers are created with respect to a specific render pass that the framebuffer is compatible with (see <>). Collectively, a render pass and a framebuffer define the complete render target state for one or more subpasses as well as the algorithmic dependencies between the subpasses. The various pipeline stages of the drawing commands for a given subpass may: execute concurrently and/or out of order, both within and across drawing commands, whilst still respecting <>. However for a given (x,y,layer,sample) sample location, certain per-sample operations are performed in <>. [[renderpass-creation]] == Render Pass Creation [open,refpage='vkCreateRenderPass',desc='Create a new render pass object',type='protos'] -- To create a render pass, call: include::../api/protos/vkCreateRenderPass.txt[] * pname:device is the logical device that creates the render pass. * pname:pCreateInfo is a pointer to an instance of the slink:VkRenderPassCreateInfo structure that describes the parameters of the render pass. * pname:pAllocator controls host memory allocation as described in the <> chapter. * pname:pRenderPass points to a sname:VkRenderPass handle in which the resulting render pass object is returned. include::../validity/protos/vkCreateRenderPass.txt[] -- [open,refpage='VkRenderPassCreateInfo',desc='Structure specifying parameters of a newly created render pass',type='structs'] -- The sname:VkRenderPassCreateInfo structure is defined as: include::../api/structs/VkRenderPassCreateInfo.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:attachmentCount is the number of attachments used by this render pass, or zero indicating no attachments. Attachments are referred to by zero-based indices in the range [0,pname:attachmentCount). * pname:pAttachments points to an array of pname:attachmentCount number of slink:VkAttachmentDescription structures describing properties of the attachments, or `NULL` if pname:attachmentCount is zero. * pname:subpassCount is the number of subpasses to create for this render pass. Subpasses are referred to by zero-based indices in the range [0,pname:subpassCount). A render pass must: have at least one subpass. * pname:pSubpasses points to an array of pname:subpassCount number of slink:VkSubpassDescription structures describing properties of the subpasses. * pname:dependencyCount is the number of dependencies between pairs of subpasses, or zero indicating no dependencies. * pname:pDependencies points to an array of pname:dependencyCount number of slink:VkSubpassDependency structures describing dependencies between pairs of subpasses, or `NULL` if pname:dependencyCount is zero. .Valid Usage **** * [[VUID-VkRenderPassCreateInfo-None-00832]] If any two subpasses operate on attachments with overlapping ranges of the same sname:VkDeviceMemory object, and at least one subpass writes to that area of sname:VkDeviceMemory, a subpass dependency must: be included (either directly or via some intermediate subpasses) between them * [[VUID-VkRenderPassCreateInfo-attachment-00833]] If the pname:attachment member of any element of pname:pInputAttachments, pname:pColorAttachments, pname:pResolveAttachments or pname:pDepthStencilAttachment, or the attachment indexed by any element of pname:pPreserveAttachments in any given element of pname:pSubpasses is bound to a range of a sname:VkDeviceMemory object that overlaps with any other attachment in any subpass (including the same subpass), the sname:VkAttachmentDescription structures describing them must: include ename:VK_ATTACHMENT_DESCRIPTION_MAY_ALIAS_BIT in pname:flags * [[VUID-VkRenderPassCreateInfo-attachment-00834]] If the pname:attachment member of any element of pname:pInputAttachments, pname:pColorAttachments, pname:pResolveAttachments or pname:pDepthStencilAttachment, or any element of pname:pPreserveAttachments in any given element of pname:pSubpasses is not ename:VK_ATTACHMENT_UNUSED, it must: be less than pname:attachmentCount * [[VUID-VkRenderPassCreateInfo-pPreserveAttachments-00835]] The value of any element of the pname:pPreserveAttachments member in any given element of pname:pSubpasses must: not be ename:VK_ATTACHMENT_UNUSED * [[VUID-VkRenderPassCreateInfo-pAttachments-00836]] For any member of pname:pAttachments with a pname:loadOp equal to ename:VK_ATTACHMENT_LOAD_OP_CLEAR, the first use of that attachment must: not specify a pname:layout equal to pname:VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL or pname:VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL. * [[VUID-VkRenderPassCreateInfo-pDependencies-00837]] For any element of pname:pDependencies, if the pname:srcSubpass is not ename:VK_SUBPASS_EXTERNAL, all stage flags included in the pname:srcStageMask member of that dependency must: be a pipeline stage supported by the <> identified by the pname:pipelineBindPoint member of the source subpass. * [[VUID-VkRenderPassCreateInfo-pDependencies-00838]] For any element of pname:pDependencies, if the pname:dstSubpass is not ename:VK_SUBPASS_EXTERNAL, all stage flags included in the pname:dstStageMask member of that dependency must: be a pipeline stage supported by the <> identified by the pname:pipelineBindPoint member of the source subpass. **** include::../validity/structs/VkRenderPassCreateInfo.txt[] -- ifdef::VK_KHX_multiview[] [[renderpass-multiview]] [open,refpage='VkRenderPassMultiviewCreateInfoKHX',desc='Structure containing multiview info for all subpasses',type='structs'] -- If the sname:VkRenderPassCreateInfo::pname:pNext list includes a sname:VkRenderPassMultiviewCreateInfoKHX structure, then that structure includes an array of view masks, view offsets, and correlation masks for the render pass. The sname:VkRenderPassMultiviewCreateInfoKHX structure is defined as: include::../api/structs/VkRenderPassMultiviewCreateInfoKHX.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:subpassCount is zero or is the number of subpasses in the render pass. * pname:pViewMasks points to an array of pname:subpassCount number of view masks, where each mask is a bitfield of view indices describing which views rendering is broadcast to in each subpass, when multiview is enabled. If pname:subpassCount is zero, each view mask is treated as zero. * pname:dependencyCount is zero or the number of dependencies in the render pass. * pname:pViewOffsets points to an array of pname:dependencyCount view offsets, one for each dependency. If pname:dependencyCount is zero, each dependency's view offset is treated as zero. Each view offset controls which views in the source subpass the views in the destination subpass depend on. * pname:correlationMaskCount is zero or a number of correlation masks. * pname:pCorrelationMasks is an array of view masks indicating sets of views that may: be more efficient to render concurrently. When a subpass uses a non-zero view mask, _multiview_ functionality is considered to be enabled. Multiview is all-or-nothing for a render pass - that is, either all subpasses must: have a non-zero view mask (though some subpasses may: have only one view) or all must: be zero. Multiview causes all drawing and clear commands in the subpass to behave as if they were broadcast to each view, where a view is represented by one layer of the framebuffer attachments. All draws and clears are broadcast to each _view index_ whose bit is set in the view mask. The view index is provided in the code:ViewIndex shader input variable, and color, depth/stencil, and input attachments all read/write the layer of the framebuffer corresponding to the view index. If the view mask is zero for all subpasses, multiview is considered to be disabled and all drawing commands execute normally, without this additional broadcasting. Some implementations may: not support multiview in conjunction with <> or <>. [[renderpass-multiview-view-local]] When multiview is enabled, the ename:VK_DEPENDENCY_VIEW_LOCAL_BIT_KHX bit in a dependency can: be used to express a view-local dependency, meaning that each view in the destination subpass depends on a single view in the source subpass. Unlike pipeline barriers, a subpass dependency can: potentially have a different view mask in the source subpass and the destination subpass. If the dependency is view-local, then each view ([eq]#dstView#) in the destination subpass depends on the view [eq]#dstView {plus} pViewOffsets[dependency]# in the source subpass. If there is not such a view in the source subpass, then this dependency does not affect that view in the destination subpass. If the dependency is not view-local, then all views in the destination subpass depend on all views in the source subpass, and the view offset is ignored. A non-zero view offset is not allowed in a self-dependency. The elements of pname:pCorrelationMasks are a set of masks of views indicating that views in the same mask may: exhibit spatial coherency between the views, making it more efficient to render them concurrently. Correlation masks must: not have a functional effect on the results of the multiview rendering. When multiview is enabled, at the beginning of each subpass all non-render pass state is undefined. In particular, each time flink:vkCmdBeginRenderPass or flink:vkCmdNextSubpass is called the graphics pipeline must: be bound, any relevant descriptor sets or vertex/index buffers must: be bound, and any relevant dynamic state or push constants must: be set before they are used. ifdef::VK_NVX_multiview_per_view_attributes[] A multiview subpass can: declare that its shaders will write per-view attributes for all views in a single invocation, by setting the ename:VK_SUBPASS_DESCRIPTION_PER_VIEW_ATTRIBUTES_BIT_NVX bit in the subpass description. The only supported per-view attributes are position and viewport mask, and per-view position and viewport masks are written to output array variables decorated with code:PositionPerViewNV and code:ViewportMaskPerViewNV, respectively. If +VK_NV_viewport_array2+ is not supported and enabled, code:ViewportMaskPerViewNV must: not be used. Values written to elements of code:PositionPerViewNV and code:ViewportMaskPerViewNV must: not depend on the code:ViewIndex. The shader must: also write to an output variable decorated with code:Position, and the value written to code:Position must: equal the value written to code:PositionPerViewNV[code:ViewIndex]. Similarly, if code:ViewportMaskPerViewNV is written to then the shader must: also write to an output variable decorated with code:ViewportMaskNV, and the value written to code:ViewportMaskNV must: equal the value written to code:ViewportMaskPerViewNV[code:ViewIndex]. Implementations will either use values taken from code:Position and code:ViewportMaskNV and invoke the shader once for each view, or will use values taken from code:PositionPerViewNV and code:ViewportMaskPerViewNV and invoke the shader fewer times. The values written to code:Position and code:ViewportMaskNV must: not depend on the values written to code:PositionPerViewNV and code:ViewportMaskPerViewNV, or vice versa (to allow compilers to eliminate the unused outputs). All attributes that do not have *PerViewNV counterparts must: not depend on code:ViewIndex. Per-view attributes are all-or-nothing for a subpass. That is, all pipelines compiled against a subpass that includes the ename:VK_SUBPASS_DESCRIPTION_PER_VIEW_ATTRIBUTES_BIT_NVX bit must: write per-view attributes to the *PerViewNV[] shader outputs, in addition to the non-per-view (e.g. code:Position) outputs. Pipelines compiled against a subpass that does not include this bit must: not include the *PerViewNV[] outputs in their interfaces. endif::VK_NVX_multiview_per_view_attributes[] .Valid Usage **** * [[VUID-VkRenderPassMultiviewCreateInfoKHX-subpassCount-00839]] If pname:subpassCount is not zero, pname:subpassCount must: be equal to the pname:subpassCount in the sname:VkRenderPassCreateInfo structure at the start of the chain * [[VUID-VkRenderPassMultiviewCreateInfoKHX-dependencyCount-00840]] If pname:dependencyCount is not zero, pname:dependencyCount must: be equal to the pname:dependencyCount in the sname:VkRenderPassCreateInfo structure at the start of the chain * [[VUID-VkRenderPassMultiviewCreateInfoKHX-pCorrelationMasks-00841]] Each view index must: not be set in more than one element of pname:pCorrelationMasks * [[VUID-VkRenderPassMultiviewCreateInfoKHX-pViewOffsets-00842]] If an element of pname:pViewOffsets is non-zero, the corresponding slink:VkSubpassDependency structure must: have different values of pname:srcSubpass and pname:dstSubpass. **** include::../validity/structs/VkRenderPassMultiviewCreateInfoKHX.txt[] -- endif::VK_KHX_multiview[] [open,refpage='VkAttachmentDescription',desc='Structure specifying an attachment description',type='structs'] -- The sname:VkAttachmentDescription structure is defined as: include::../api/structs/VkAttachmentDescription.txt[] * pname:flags is a bitmask of elink:VkAttachmentDescriptionFlagBits specifying additional properties of the attachment. * pname:format is a elink:VkFormat value specifying the format of the image that will be used for the attachment. * pname:samples is the number of samples of the image as defined in elink:VkSampleCountFlagBits. * pname:loadOp is a elink:VkAttachmentLoadOp value specifying how the contents of color and depth components of the attachment are treated at the beginning of the subpass where it is first used. * pname:storeOp is a elink:VkAttachmentStoreOp value specifying how the contents of color and depth components of the attachment are treated at the end of the subpass where it is last used. * pname:stencilLoadOp is a elink:VkAttachmentLoadOp value specifying how the contents of stencil components of the attachment are treated at the beginning of the subpass where it is first used. * pname:stencilStoreOp is a elink:VkAttachmentStoreOp value specifying how the contents of stencil components of the attachment are treated at the end of the last subpass where it is used. * pname:initialLayout is the layout the attachment image subresource will be in when a render pass instance begins. * pname:finalLayout is the layout the attachment image subresource will be transitioned to when a render pass instance ends. During a render pass instance, an attachment can: use a different layout in each subpass, if desired. [[renderpass-load-store-ops]] If the attachment uses a color format, then pname:loadOp and pname:storeOp are used, and pname:stencilLoadOp and pname:stencilStoreOp are ignored. If the format has depth and/or stencil components, pname:loadOp and pname:storeOp apply only to the depth data, while pname:stencilLoadOp and pname:stencilStoreOp define how the stencil data is handled. pname:loadOp and pname:stencilLoadOp define the _load operations_ that execute as part of the first subpass that uses the attachment. pname:storeOp and pname:stencilStoreOp define the _store operations_ that execute as part of the last subpass that uses the attachment. The load operation for each value in an attachment used by a subpass happens-before any command recorded into that subpass reads from that value. Load operations for attachments with a depth/stencil format execute in the ename:VK_PIPELINE_STAGE_EARLY_FRAGMENT_TESTS_BIT pipeline stage. Load operations for attachments with a color format execute in the ename:VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT pipeline stage. Store operations for each value in an attachment used by a subpass happen-after any command recorded into that subpass writes to that value. Store operations for attachments with a depth/stencil format execute in the ename:VK_PIPELINE_STAGE_LATE_FRAGMENT_TESTS_BIT pipeline stage. Store operations for attachments with a color format execute in the ename:VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT pipeline stage. If an attachment is not used by any subpass, then pname:loadOp, pname:storeOp, pname:stencilStoreOp, and pname:stencilLoadOp are ignored, and the attachment's memory contents will not be modified by execution of a render pass instance. ifdef::VK_KHX_multiview[] The load and store operations apply on the first and last use of each view in the render pass, respectively. If a view index of an attachment is not included in the view mask in any subpass that uses it, then the load and store operations are ignored, and the attachment's memory contents will not be modified by execution of a render pass instance. endif::VK_KHX_multiview[] [[renderpass-precision]] During a render pass instance, input/color attachments with color formats that have a component size of 8, 16, or 32 bits must: be represented in the attachment's format throughout the instance. Attachments with other floating- or fixed-point color formats, or with depth components may: be represented in a format with a precision higher than the attachment format, but must: be represented with the same range. When such a component is loaded via the pname:loadOp, it will be converted into an implementation-dependent format used by the render pass. Such components must: be converted from the render pass format, to the format of the attachment, before they are resolved or stored at the end of a render pass instance via pname:storeOp. Conversions occur as described in <> and <>. [[renderpass-aliasing]] If pname:flags includes ename:VK_ATTACHMENT_DESCRIPTION_MAY_ALIAS_BIT, then the attachment is treated as if it shares physical memory with another attachment in the same render pass. This information limits the ability of the implementation to reorder certain operations (like layout transitions and the pname:loadOp) such that it is not improperly reordered against other uses of the same physical memory via a different attachment. This is described in more detail below. .Valid Usage **** * [[VUID-VkAttachmentDescription-finalLayout-00843]] pname:finalLayout must: not be ename:VK_IMAGE_LAYOUT_UNDEFINED or ename:VK_IMAGE_LAYOUT_PREINITIALIZED **** include::../validity/structs/VkAttachmentDescription.txt[] -- [open,refpage='VkAttachmentDescriptionFlagBits',desc='Bitmask specifying additional properties of an attachment',type='enums'] -- Bits which can: be set in slink:VkAttachmentDescription::pname:flags describing additional properties of the attachment are: include::../api/enums/VkAttachmentDescriptionFlagBits.txt[] * ename:VK_ATTACHMENT_DESCRIPTION_MAY_ALIAS_BIT specifies that the attachment aliases the same device memory as other attachments. -- [open,refpage='VkAttachmentLoadOp',desc='Specify how contents of an attachment are treated at the beginning of a subpass',type='enums'] -- Possible values of slink:VkAttachmentDescription::pname:loadOp and pname:stencilLoadOp, specifying how the contents of the attachment are treated, are: include::../api/enums/VkAttachmentLoadOp.txt[] * ename:VK_ATTACHMENT_LOAD_OP_LOAD specifies that the previous contents of the image within the render area will be preserved. For attachments with a depth/stencil format, this uses the access type ename:VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_READ_BIT. For attachments with a color format, this uses the access type ename:VK_ACCESS_COLOR_ATTACHMENT_READ_BIT. * ename:VK_ATTACHMENT_LOAD_OP_CLEAR specifies that the contents within the render area will be cleared to a uniform value, which is specified when a render pass instance is begun. For attachments with a depth/stencil format, this uses the access type ename:VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT. For attachments with a color format, this uses the access type ename:VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT. * ename:VK_ATTACHMENT_LOAD_OP_DONT_CARE specifies that the previous contents within the area need not be preserved; the contents of the attachment will be undefined inside the render area. For attachments with a depth/stencil format, this uses the access type ename:VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT. For attachments with a color format, this uses the access type ename:VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT. -- [open,refpage='VkAttachmentStoreOp',desc='Specify how contents of an attachment are treated at the end of a subpass',type='enums'] -- Possible values of slink:VkAttachmentDescription::pname:storeOp and pname:stencilStoreOp, specifying how the contents of the attachment are treated, are: include::../api/enums/VkAttachmentStoreOp.txt[] * ename:VK_ATTACHMENT_STORE_OP_STORE specifies the contents generated during the render pass and within the render area are written to memory. For attachments with a depth/stencil format, this uses the access type ename:VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT. For attachments with a color format, this uses the access type ename:VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT. * ename:VK_ATTACHMENT_STORE_OP_DONT_CARE specifies the contents within the render area are not needed after rendering, and may: be discarded; the contents of the attachment will be undefined inside the render area. For attachments with a depth/stencil format, this uses the access type ename:VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT. For attachments with a color format, this uses the access type ename:VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT. -- ifdef::editing-notes[] [NOTE] .editing-note ==== TODO (Jon) - the following text may need to be moved back to combine with flink:vkCreateRenderPass above for automatic ref page generation. ==== endif::editing-notes[] If a render pass uses multiple attachments that alias the same device memory, those attachments must: each include the ename:VK_ATTACHMENT_DESCRIPTION_MAY_ALIAS_BIT bit in their attachment description flags. Attachments aliasing the same memory occurs in multiple ways: * Multiple attachments being assigned the same image view as part of framebuffer creation. * Attachments using distinct image views that correspond to the same image subresource of an image. * Attachments using views of distinct image subresources which are bound to overlapping memory ranges. .Note [NOTE] ==== Render passes must: include subpass dependencies (either directly or via a subpass dependency chain) between any two subpasses that operate on the same attachment or aliasing attachments and those subpass dependencies must: include execution and memory dependencies separating uses of the aliases, if at least one of those subpasses writes to one of the aliases. These dependencies must: not include the ename:VK_DEPENDENCY_BY_REGION_BIT if the aliases are views of distinct image subresources which overlap in memory. ==== Multiple attachments that alias the same memory must: not be used in a single subpass. A given attachment index must: not be used multiple times in a single subpass, with one exception: two subpass attachments can: use the same attachment index if at least one use is as an input attachment and neither use is as a resolve or preserve attachment. In other words, the same view can: be used simultaneously as an input and color or depth/stencil attachment, but must: not be used as multiple color or depth/stencil attachments nor as resolve or preserve attachments. The precise set of valid scenarios is described in more detail <>. If a set of attachments alias each other, then all except the first to be used in the render pass must: use an pname:initialLayout of ename:VK_IMAGE_LAYOUT_UNDEFINED, since the earlier uses of the other aliases make their contents undefined. Once an alias has been used and a different alias has been used after it, the first alias must: not be used in any later subpasses. However, an application can: assign the same image view to multiple aliasing attachment indices, which allows that image view to be used multiple times even if other aliases are used in between. [NOTE] .Note ==== Once an attachment needs the ename:VK_ATTACHMENT_DESCRIPTION_MAY_ALIAS_BIT bit, there should: be no additional cost of introducing additional aliases, and using these additional aliases may: allow more efficient clearing of the attachments on multiple uses via ename:VK_ATTACHMENT_LOAD_OP_CLEAR. ==== [open,refpage='VkSubpassDescription',desc='Structure specifying a subpass description',type='structs'] -- The sname:VkSubpassDescription structure is defined as: include::../api/structs/VkSubpassDescription.txt[] * pname:flags is a bitmask of elink:VkSubpassDescriptionFlagBits specifying usage of the subpass. * pname:pipelineBindPoint is a elink:VkPipelineBindPoint value specifying whether this is a compute or graphics subpass. Currently, only graphics subpasses are supported. * pname:inputAttachmentCount is the number of input attachments. * pname:pInputAttachments is an array of slink:VkAttachmentReference structures (defined below) that lists which of the render pass's attachments can: be read in the shader during the subpass, and what layout each attachment will be in during the subpass. Each element of the array corresponds to an input attachment unit number in the shader, i.e. if the shader declares an input variable `layout(input_attachment_index=X, set=Y, binding=Z)` then it uses the attachment provided in pname:pInputAttachments[X]. Input attachments must: also be bound to the pipeline with a descriptor set, with the input attachment descriptor written in the location (set=Y, binding=Z). * pname:colorAttachmentCount is the number of color attachments. * pname:pColorAttachments is an array of pname:colorAttachmentCount slink:VkAttachmentReference structures that lists which of the render pass's attachments will be used as color attachments in the subpass, and what layout each attachment will be in during the subpass. Each element of the array corresponds to a fragment shader output location, i.e. if the shader declared an output variable `layout(location=X)` then it uses the attachment provided in pname:pColorAttachments[X]. * pname:pResolveAttachments is `NULL` or an array of pname:colorAttachmentCount slink:VkAttachmentReference structures that lists which of the render pass's attachments are resolved to at the end of the subpass, and what layout each attachment will be in during the multisample resolve operation. If pname:pResolveAttachments is not `NULL`, each of its elements corresponds to a color attachment (the element in pname:pColorAttachments at the same index), and a multisample resolve operation is defined for each attachment. At the end of each subpass, multisample resolve operations read the subpass's color attachments, and resolve the samples for each pixel to the same pixel location in the corresponding resolve attachments, unless the resolve attachment index is ename:VK_ATTACHMENT_UNUSED. If the first use of an attachment in a render pass is as a resolve attachment, then the pname:loadOp is effectively ignored as the resolve is guaranteed to overwrite all pixels in the render area. * pname:pDepthStencilAttachment is a pointer to a slink:VkAttachmentReference specifying which attachment will be used for depth/stencil data and the layout it will be in during the subpass. Setting the attachment index to ename:VK_ATTACHMENT_UNUSED or leaving this pointer as `NULL` indicates that no depth/stencil attachment will be used in the subpass. * pname:preserveAttachmentCount is the number of preserved attachments. * pname:pPreserveAttachments is an array of pname:preserveAttachmentCount render pass attachment indices describing the attachments that are not used by a subpass, but whose contents must: be preserved throughout the subpass. The contents of an attachment within the render area become undefined at the start of a subpass *S* if all of the following conditions are true: * The attachment is used as a color, depth/stencil, or resolve attachment in any subpass in the render pass. * There is a subpass *S~1~* that uses or preserves the attachment, and a subpass dependency from *S~1~* to *S*. * The attachment is not used or preserved in subpass *S*. Once the contents of an attachment become undefined in subpass *S*, they remain undefined for subpasses in subpass dependency chains starting with subpass *S* until they are written again. However, they remain valid for subpasses in other subpass dependency chains starting with subpass *S~1~* if those subpasses use or preserve the attachment. .Valid Usage **** * [[VUID-VkSubpassDescription-pipelineBindPoint-00844]] pname:pipelineBindPoint must: be ename:VK_PIPELINE_BIND_POINT_GRAPHICS * [[VUID-VkSubpassDescription-colorAttachmentCount-00845]] pname:colorAttachmentCount must: be less than or equal to sname:VkPhysicalDeviceLimits::pname:maxColorAttachments * [[VUID-VkSubpassDescription-loadOp-00846]] If the first use of an attachment in this render pass is as an input attachment, and the attachment is not also used as a color or depth/stencil attachment in the same subpass, then pname:loadOp must: not be ename:VK_ATTACHMENT_LOAD_OP_CLEAR * [[VUID-VkSubpassDescription-pResolveAttachments-00847]] If pname:pResolveAttachments is not `NULL`, for each resolve attachment that does not have the value ename:VK_ATTACHMENT_UNUSED, the corresponding color attachment must: not have the value ename:VK_ATTACHMENT_UNUSED * [[VUID-VkSubpassDescription-pResolveAttachments-00848]] If pname:pResolveAttachments is not `NULL`, the sample count of each element of pname:pColorAttachments must: be anything other than ename:VK_SAMPLE_COUNT_1_BIT * [[VUID-VkSubpassDescription-pResolveAttachments-00849]] Any given element of pname:pResolveAttachments must: have a sample count of ename:VK_SAMPLE_COUNT_1_BIT * [[VUID-VkSubpassDescription-pResolveAttachments-00850]] Any given element of pname:pResolveAttachments must: have the same elink:VkFormat as its corresponding color attachment * [[VUID-VkSubpassDescription-pColorAttachments-01417]] All attachments in pname:pColorAttachments that are not ename:VK_ATTACHMENT_UNUSED must: have the same sample count ifndef::VK_NV_framebuffer_mixed_samples[] * [[VUID-VkSubpassDescription-pDepthStencilAttachment-01418]] If pname:pDepthStencilAttachment is not ename:VK_ATTACHMENT_UNUSED and any attachments in pname:pColorAttachments are not ename:VK_ATTACHMENT_UNUSED, they must: have the same sample count endif::VK_NV_framebuffer_mixed_samples[] * [[VUID-VkSubpassDescription-None-00852]] If any input attachments are ename:VK_ATTACHMENT_UNUSED, then any pipelines bound during the subpass must: not access those input attachments from the fragment shader * [[VUID-VkSubpassDescription-attachment-00853]] The pname:attachment member of any element of pname:pPreserveAttachments must: not be ename:VK_ATTACHMENT_UNUSED * [[VUID-VkSubpassDescription-pPreserveAttachments-00854]] Any given element of pname:pPreserveAttachments must: not also be an element of any other member of the subpass description * [[VUID-VkSubpassDescription-layout-00855]] If any attachment is used as both an input attachment and a color or depth/stencil attachment, then each use must: use the same pname:layout ifdef::VK_NVX_multiview_per_view_attributes[] * [[VUID-VkSubpassDescription-flags-00856]] If pname:flags includes ename:VK_SUBPASS_DESCRIPTION_PER_VIEW_POSITION_X_ONLY_BIT_NVX, it must: also include ename:VK_SUBPASS_DESCRIPTION_PER_VIEW_ATTRIBUTES_BIT_NVX. endif::VK_NVX_multiview_per_view_attributes[] **** include::../validity/structs/VkSubpassDescription.txt[] -- [open,refpage='VkSubpassDescriptionFlagBits',desc='Bitmask specifying usage of a subpass',type='enums'] -- Bits which can: be set in slink:VkSubpassDescription::pname:flags, specifying usage of the subpass, are: include::../api/enums/VkSubpassDescriptionFlagBits.txt[] ifdef::VK_NVX_multiview_per_view_attributes[] * ename:VK_SUBPASS_DESCRIPTION_PER_VIEW_ATTRIBUTES_BIT_NVX specifies that shaders compiled for this subpass write the attributes for all views in a single invocation of each vertex processing stage. All pipelines compiled against a subpass that includes this bit must: write per-view attributes to the code:*PerViewNV[] shader outputs, in addition to the non-per-view (e.g. code:Position) outputs. * ename:VK_SUBPASS_DESCRIPTION_PER_VIEW_POSITION_X_ONLY_BIT_NVX specifies that shaders compiled for this subpass use per-view positions which only differ in value in the x component. Per-view viewport mask can: also be used. endif::VK_NVX_multiview_per_view_attributes[] -- [open,refpage='VkAttachmentReference',desc='Structure specifying an attachment reference',type='structs'] -- The sname:VkAttachmentReference structure is defined as: include::../api/structs/VkAttachmentReference.txt[] * pname:attachment is the index of the attachment of the render pass, and corresponds to the index of the corresponding element in the pname:pAttachments array of the sname:VkRenderPassCreateInfo structure. If any color or depth/stencil attachments are ename:VK_ATTACHMENT_UNUSED, then no writes occur for those attachments. * pname:layout is a elink:VkImageLayout value specifying the layout the attachment uses during the subpass. .Valid Usage **** * [[VUID-VkAttachmentReference-layout-00857]] pname:layout must: not be ename:VK_IMAGE_LAYOUT_UNDEFINED or ename:VK_IMAGE_LAYOUT_PREINITIALIZED **** include::../validity/structs/VkAttachmentReference.txt[] -- [open,refpage='VkSubpassDependency',desc='Structure specifying a subpass dependency',type='structs'] -- The sname:VkSubpassDependency structure is defined as: include::../api/structs/VkSubpassDependency.txt[] * pname:srcSubpass is the subpass index of the first subpass in the dependency, or ename:VK_SUBPASS_EXTERNAL. * pname:dstSubpass is the subpass index of the second subpass in the dependency, or ename:VK_SUBPASS_EXTERNAL. * pname:srcStageMask is a bitmask of elink:VkPipelineStageFlagBits specifying the <>. * pname:dstStageMask is a bitmask of elink:VkPipelineStageFlagBits specifying the <> * pname:srcAccessMask is a bitmask of elink:VkAccessFlagBits specifying a <>. * pname:dstAccessMask is a bitmask of elink:VkAccessFlagBits specifying a <>. * pname:dependencyFlags is a bitmask of elink:VkDependencyFlagBits. If pname:srcSubpass is equal to pname:dstSubpass then the slink:VkSubpassDependency describes a <>, and only constrains the pipeline barriers allowed within a subpass instance. Otherwise, when a render pass instance which includes a subpass dependency is submitted to a queue, it defines a memory dependency between the subpasses identified by pname:srcSubpass and pname:dstSubpass. If pname:srcSubpass is equal to ename:VK_SUBPASS_EXTERNAL, the first <> includes commands submitted to the queue before the render pass instance began. Otherwise, the first set of commands includes all commands submitted as part of the subpass instance identified by pname:srcSubpass and any load, store or multisample resolve operations on attachments used in pname:srcSubpass. In either case, the first synchronization scope is limited to operations on the pipeline stages determined by the <> specified by pname:srcStageMask. If pname:dstSubpass is equal to ename:VK_SUBPASS_EXTERNAL, the second <> includes commands submitted after the render pass instance is ended. Otherwise, the second set of commands includes all commands submitted as part of the subpass instance identified by pname:dstSubpass and any load, store or multisample resolve operations on attachments used in pname:dstSubpass. In either case, the second synchronization scope is limited to operations on the pipeline stages determined by the <> specified by pname:dstStageMask. The first <> is limited to access in the pipeline stages determined by the <> specified by pname:srcStageMask. It is also limited to access types in the <> specified by pname:srcAccessMask. The second <> is limited to access in the pipeline stages determined by the <> specified by pname:dstStageMask. It is also limited to access types in the <> specified by pname:dstAccessMask. The <> defined by a subpass dependency affect the execution of <> within the render pass. .Valid Usage **** * [[VUID-VkSubpassDependency-srcSubpass-00858]] If pname:srcSubpass is not ename:VK_SUBPASS_EXTERNAL, pname:srcStageMask must: not include ename:VK_PIPELINE_STAGE_HOST_BIT * [[VUID-VkSubpassDependency-dstSubpass-00859]] If pname:dstSubpass is not ename:VK_SUBPASS_EXTERNAL, pname:dstStageMask must: not include ename:VK_PIPELINE_STAGE_HOST_BIT * [[VUID-VkSubpassDependency-srcStageMask-00860]] If the <> feature is not enabled, pname:srcStageMask must: not contain ename:VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT * [[VUID-VkSubpassDependency-dstStageMask-00861]] If the <> feature is not enabled, pname:dstStageMask must: not contain ename:VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT * [[VUID-VkSubpassDependency-srcStageMask-00862]] If the <> feature is not enabled, pname:srcStageMask must: not contain ename:VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT or ename:VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT * [[VUID-VkSubpassDependency-dstStageMask-00863]] If the <> feature is not enabled, pname:dstStageMask must: not contain ename:VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT or ename:VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT * [[VUID-VkSubpassDependency-srcSubpass-00864]] pname:srcSubpass must: be less than or equal to pname:dstSubpass, unless one of them is ename:VK_SUBPASS_EXTERNAL, to avoid cyclic dependencies and ensure a valid execution order * [[VUID-VkSubpassDependency-srcSubpass-00865]] pname:srcSubpass and pname:dstSubpass must: not both be equal to ename:VK_SUBPASS_EXTERNAL * [[VUID-VkSubpassDependency-srcSubpass-00866]] If pname:srcSubpass is equal to pname:dstSubpass, pname:srcStageMask and pname:dstStageMask must: only contain one of ename:VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT, ename:VK_PIPELINE_STAGE_DRAW_INDIRECT_BIT, ename:VK_PIPELINE_STAGE_VERTEX_INPUT_BIT, ename:VK_PIPELINE_STAGE_VERTEX_SHADER_BIT, ename:VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT, ename:VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT, ename:VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT, ename:VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT, ename:VK_PIPELINE_STAGE_EARLY_FRAGMENT_TESTS_BIT, ename:VK_PIPELINE_STAGE_LATE_FRAGMENT_TESTS_BIT, ename:VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT, ename:VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT, or ename:VK_PIPELINE_STAGE_ALL_GRAPHICS_BIT * [[VUID-VkSubpassDependency-srcSubpass-00867]] If pname:srcSubpass is equal to pname:dstSubpass and not all of the stages in pname:srcStageMask and pname:dstStageMask are <>, the <> pipeline stage in pname:srcStageMask must: be <> than or equal to the <> pipeline stage in pname:dstStageMask * [[VUID-VkSubpassDependency-srcAccessMask-00868]] Any access flag included in pname:srcAccessMask must: be supported by one of the pipeline stages in pname:srcStageMask, as specified in the <>. * [[VUID-VkSubpassDependency-dstAccessMask-00869]] Any access flag included in pname:dstAccessMask must: be supported by one of the pipeline stages in pname:dstStageMask, as specified in the <>. ifdef::VK_KHX_multiview[] * [[VUID-VkSubpassDependency-dependencyFlags-00870]] If pname:dependencyFlags includes ename:VK_DEPENDENCY_VIEW_LOCAL_BIT_KHX, then both pname:srcSubpass and pname:dstSubpass must: not equal ename:VK_SUBPASS_EXTERNAL * [[VUID-VkSubpassDependency-dependencyFlags-00871]] If pname:dependencyFlags includes ename:VK_DEPENDENCY_VIEW_LOCAL_BIT_KHX, then the render pass must: have multiview enabled * [[VUID-VkSubpassDependency-srcSubpass-00872]] If pname:srcSubpass equals pname:dstSubpass and that subpass has more than one bit set in the view mask, then pname:dependencyFlags must: include ename:VK_DEPENDENCY_VIEW_LOCAL_BIT_KHX endif::VK_KHX_multiview[] **** include::../validity/structs/VkSubpassDependency.txt[] -- ifdef::VK_KHX_multiview[] When multiview is enabled, the execution of the multiple views of one subpass may: not occur simultaneously or even back-to-back, and rather may: be interleaved with the execution of other subpasses. The load and store operations apply to attachments on a per-view basis. For example, an attachment using ename:VK_ATTACHMENT_LOAD_OP_CLEAR will have each view cleared on first use, but the first use of one view may be temporally distant from the first use of another view. [NOTE] .Note ==== A good mental model for multiview is to think of a multiview subpass as if it were a collection of individual (per-view) subpasses that are logically grouped together and described as a single multiview subpass in the API. Similarly, a multiview attachment can be thought of like several individual attachments that happen to be layers in a single image. A view-local dependency between two multiview subpasses acts like a set of one-to-one dependencies between corresponding pairs of per-view subpasses. A view-global dependency between two multiview subpasses acts like a set of [eq]#N {times} M# dependencies between all pairs of per-view subpasses in the source and destination. Thus, it is a more compact representation which also makes clear the commonality and reuse that is present between views in a subpass. This interpretation motivates the answers to questions like "when does the load op apply" - it is on the first use of each view of an attachment, as if each view were a separate attachment. ==== endif::VK_KHX_multiview[] ifdef::editing-notes[] [NOTE] .editing-note ==== The following two alleged implicit dependencies are practically no-ops, as the operations they describe are already guaranteed by semaphores and submission order (so they're almost entirely no-ops on their own). The *only* reason they exist is because it simplifies reasoning about where <> happen. Further rewrites of this chapter could potentially remove the need for these. ==== endif::editing-notes[] If there is no subpass dependency from ename:VK_SUBPASS_EXTERNAL to the first subpass that uses an attachment, then an implicit subpass dependency exists from ename:VK_SUBPASS_EXTERNAL to the first subpass it is used in. The subpass dependency operates as if defined with the following parameters: [source,c] --------------------------------------------------- VkSubpassDependency implicitDependency = { .srcSubpass = VK_SUBPASS_EXTERNAL; .dstSubpass = firstSubpass; // First subpass attachment is used in .srcStageMask = VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT; .dstStageMask = VK_PIPELINE_STAGE_ALL_COMMANDS_BIT; .srcAccessMask = 0; .dstAccessMask = VK_ACCESS_INPUT_ATTACHMENT_READ_BIT | VK_ACCESS_COLOR_ATTACHMENT_READ_BIT | VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT | VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_READ_BIT | VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT; .dependencyFlags = 0; }; --------------------------------------------------- Similarly, if there is no subpass dependency from the last subpass that uses an attachment to ename:VK_SUBPASS_EXTERNAL, then an implicit subpass dependency exists from the last subpass it is used in to ename:VK_SUBPASS_EXTERNAL. The subpass dependency operates as if defined with the following parameters: [source,c] --------------------------------------------------- VkSubpassDependency implicitDependency = { .srcSubpass = lastSubpass; // Last subpass attachment is used in .dstSubpass = VK_SUBPASS_EXTERNAL; .srcStageMask = VK_PIPELINE_STAGE_ALL_COMMANDS_BIT; .dstStageMask = VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT; .srcAccessMask = VK_ACCESS_INPUT_ATTACHMENT_READ_BIT | VK_ACCESS_COLOR_ATTACHMENT_READ_BIT | VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT | VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_READ_BIT | VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT; .dstAccessMask = 0; .dependencyFlags = 0; }; --------------------------------------------------- [[renderpass-layout-transitions]] As subpasses may: overlap or execute out of order with regards to other subpasses unless a subpass dependency chain describes otherwise, the layout transitions required between subpasses cannot: be known to an application. Instead, an application provides the layout that each attachment must: be in at the start and end of a renderpass, and the layout it must: be in during each subpass it is used in. The implementation then must: execute layout transitions between subpasses in order to guarantee that the images are in the layouts required by each subpass, and in the final layout at the end of the render pass. Automatic layout transitions away from the layout used in a subpass happen-after the availability operations for all dependencies with that subpass as the pname:srcSubpass. Automatic layout transitions into the layout used in a subpass happen-before the visibility operations for all dependencies with that subpass as the pname:dstSubpass. Automatic layout transitions away from pname:initialLayout happens-after the availability operations for all dependencies with a pname:srcSubpass equal to ename:VK_SUBPASS_EXTERNAL, where pname:dstSubpass uses the attachment that will be transitioned. For attachments created with ename:VK_ATTACHMENT_DESCRIPTION_MAY_ALIAS_BIT, automatic layout transitions away from pname:initialLayout happen-after the availability operations for all dependencies with a pname:srcSubpass equal to ename:VK_SUBPASS_EXTERNAL, where pname:dstSubpass uses any aliased attachment. Automatic layout transitions into pname:finalLayout happens-before the visibility operations for all dependencies with a pname:dstSubpass equal to ename:VK_SUBPASS_EXTERNAL, where pname:srcSubpass uses the attachment that will be transitioned. For attachments created with ename:VK_ATTACHMENT_DESCRIPTION_MAY_ALIAS_BIT, automatic layout transitions into pname:finalLayout happen-before the visibility operations for all dependencies with a pname:dstSubpass equal to ename:VK_SUBPASS_EXTERNAL, where pname:srcSubpass uses any aliased attachment. If two subpasses use the same attachment in different layouts, and both layouts are read-only, no subpass dependency needs to be specified between those subpasses. If an implementation treats those layouts separately, it must: insert an implicit subpass dependency between those subpasses to separate the uses in each layout. The subpass dependency operates as if defined with the following parameters: [source,c] --------------------------------------------------- // Used for input attachments VkPipelineStageFlags inputAttachmentStages = VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT; VkAccessFlags inputAttachmentAccess = VK_ACCESS_INPUT_ATTACHMENT_READ_BIT; // Used for depth/stencil attachments VkPipelineStageFlags depthStencilAttachmentStages = VK_PIPELINE_STAGE_EARLY_FRAGMENT_TESTS_BIT | VK_PIPELINE_STAGE_LATE_FRAGMENT_TESTS_BIT; VkAccessFlags depthStencilAttachmentAccess = VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_READ_BIT; VkSubpassDependency implicitDependency = { .srcSubpass = firstSubpass; .dstSubpass = secondSubpass; .srcStageMask = inputAttachmentStages | depthStencilAttachmentStages; .dstStageMask = inputAttachmentStages | depthStencilAttachmentStages; .srcAccessMask = inputAttachmentAccess | depthStencilAttachmentAccess; .dstAccessMask = inputAttachmentAccess | depthStencilAttachmentAccess; .dependencyFlags = 0; }; --------------------------------------------------- [[renderpass-feedbackloop]] If a subpass uses the same attachment as both an input attachment and either a color attachment or a depth/stencil attachment, writes via the color or depth/stencil attachment are not automatically made visible to reads via the input attachment, causing a _feedback loop_, except in any of the following conditions: * If the color components or depth/stencil components read by the input attachment are mutually exclusive with the components written by the color or depth/stencil attachments, then there is no feedback loop. This requires the graphics pipelines used by the subpass to disable writes to color components that are read as inputs via the pname:colorWriteMask, and to disable writes to depth/stencil components that are read as inputs via pname:depthWriteEnable or pname:stencilTestEnable. * If the attachment is used as an input attachment and depth/stencil attachment only, and the depth/stencil attachment is not written to. * If a memory dependency is inserted between when the attachment is written and when it is subsequently read by later fragments. <> expressing a <> are the only way to achieve this, and one must: be inserted every time a fragment will read values at a particular sample (x, y, layer, sample) coordinate, if those values have been written since the most recent pipeline barrier; or the since start of the subpass if there have been no pipeline barriers since the start of the subpass. An attachment used as both an input attachment and a color attachment must: be in the ifdef::VK_KHR_shared_presentable_image[] ename:VK_IMAGE_LAYOUT_SHARED_PRESENT_KHR or endif::VK_KHR_shared_presentable_image[] ename:VK_IMAGE_LAYOUT_GENERAL layout. An attachment used as an input attachment and depth/stencil attachment must: be in the ifdef::VK_KHR_shared_presentable_image[] ename:VK_IMAGE_LAYOUT_SHARED_PRESENT_KHR, endif::VK_KHR_shared_presentable_image[] ename:VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL, or ename:VK_IMAGE_LAYOUT_GENERAL layout. An attachment must: not be used as both a depth/stencil attachment and a color attachment. [open,refpage='vkDestroyRenderPass',desc='Destroy a render pass object',type='protos'] -- To destroy a render pass, call: include::../api/protos/vkDestroyRenderPass.txt[] * pname:device is the logical device that destroys the render pass. * pname:renderPass is the handle of the render pass to destroy. * pname:pAllocator controls host memory allocation as described in the <> chapter. .Valid Usage **** * [[VUID-vkDestroyRenderPass-renderPass-00873]] All submitted commands that refer to pname:renderPass must: have completed execution * [[VUID-vkDestroyRenderPass-renderPass-00874]] If sname:VkAllocationCallbacks were provided when pname:renderPass was created, a compatible set of callbacks must: be provided here * [[VUID-vkDestroyRenderPass-renderPass-00875]] If no sname:VkAllocationCallbacks were provided when pname:renderPass was created, pname:pAllocator must: be `NULL` **** include::../validity/protos/vkDestroyRenderPass.txt[] -- [[renderpass-compatibility]] == Render Pass Compatibility Framebuffers and graphics pipelines are created based on a specific render pass object. They must: only be used with that render pass object, or one compatible with it. Two attachment references are compatible if they have matching format and sample count, or are both ename:VK_ATTACHMENT_UNUSED or the pointer that would contain the reference is `NULL`. Two arrays of attachment references are compatible if all corresponding pairs of attachments are compatible. If the arrays are of different lengths, attachment references not present in the smaller array are treated as ename:VK_ATTACHMENT_UNUSED. Two render passes are compatible if their corresponding color, input, resolve, and depth/stencil attachment references are compatible and if they are otherwise identical except for: * Initial and final image layout in attachment descriptions * Load and store operations in attachment descriptions * Image layout in attachment references A framebuffer is compatible with a render pass if it was created using the same render pass or a compatible render pass. == Framebuffers [open,refpage='VkFramebuffer',desc='Opaque handle to a framebuffer object',type='handles'] -- Render passes operate in conjunction with _framebuffers_. Framebuffers represent a collection of specific memory attachments that a render pass instance uses. Framebuffers are represented by sname:VkFramebuffer handles: include::../api/handles/VkFramebuffer.txt[] -- [open,refpage='vkCreateFramebuffer',desc='Create a new framebuffer object',type='protos'] -- To create a framebuffer, call: include::../api/protos/vkCreateFramebuffer.txt[] * pname:device is the logical device that creates the framebuffer. * pname:pCreateInfo points to a slink:VkFramebufferCreateInfo structure which describes additional information about framebuffer creation. * pname:pAllocator controls host memory allocation as described in the <> chapter. * pname:pFramebuffer points to a sname:VkFramebuffer handle in which the resulting framebuffer object is returned. include::../validity/protos/vkCreateFramebuffer.txt[] -- [open,refpage='VkFramebufferCreateInfo',desc='Structure specifying parameters of a newly created framebuffer',type='structs'] -- The sname:VkFramebufferCreateInfo structure is defined as: include::../api/structs/VkFramebufferCreateInfo.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:renderPass is a render pass that defines what render passes the framebuffer will be compatible with. See <> for details. * pname:attachmentCount is the number of attachments. * pname:pAttachments is an array of sname:VkImageView handles, each of which will be used as the corresponding attachment in a render pass instance. * pname:width, pname:height and pname:layers define the dimensions of the framebuffer. ifdef::VK_KHX_multiview[] If the render pass uses multiview, then pname:layers must: be one and each attachment requires a number of layers that is greater than the maximum bit index set in the view mask in the subpasses in which it is used. endif::VK_KHX_multiview[] Image subresources used as attachments must: not be used via any non-attachment usage for the duration of a render pass instance. [NOTE] .Note ==== This restriction means that the render pass has full knowledge of all uses of all of the attachments, so that the implementation is able to make correct decisions about when and how to perform layout transitions, when to overlap execution of subpasses, etc. ==== [[renderpass-noattachments]] It is legal for a subpass to use no color or depth/stencil attachments, and rather use shader side effects such as image stores and atomics to produce an output. In this case, the subpass continues to use the pname:width, pname:height, and pname:layers of the framebuffer to define the dimensions of the rendering area, and the pname:rasterizationSamples from each pipeline's slink:VkPipelineMultisampleStateCreateInfo to define the number of samples used in rasterization; however, if slink:VkPhysicalDeviceFeatures::pname:variableMultisampleRate is code:VK_FALSE, then all pipelines to be bound with a given zero-attachment subpass must: have the same value for slink:VkPipelineMultisampleStateCreateInfo::pname:rasterizationSamples. .Valid Usage **** * [[VUID-VkFramebufferCreateInfo-attachmentCount-00876]] pname:attachmentCount must: be equal to the attachment count specified in pname:renderPass * [[VUID-VkFramebufferCreateInfo-pAttachments-00877]] Any given element of pname:pAttachments that is used as a color attachment or resolve attachment by pname:renderPass must: have been created with a pname:usage value including ename:VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT * [[VUID-VkFramebufferCreateInfo-pAttachments-00878]] Any given element of pname:pAttachments that is used as a depth/stencil attachment by pname:renderPass must: have been created with a pname:usage value including ename:VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT * [[VUID-VkFramebufferCreateInfo-pAttachments-00879]] Any given element of pname:pAttachments that is used as an input attachment by pname:renderPass must: have been created with a pname:usage value including ename:VK_IMAGE_USAGE_INPUT_ATTACHMENT_BIT * [[VUID-VkFramebufferCreateInfo-pAttachments-00880]] Any given element of pname:pAttachments must: have been created with an elink:VkFormat value that matches the elink:VkFormat specified by the corresponding sname:VkAttachmentDescription in pname:renderPass * [[VUID-VkFramebufferCreateInfo-pAttachments-00881]] Any given element of pname:pAttachments must: have been created with a pname:samples value that matches the pname:samples value specified by the corresponding sname:VkAttachmentDescription in pname:renderPass * [[VUID-VkFramebufferCreateInfo-pAttachments-00882]] Any given element of pname:pAttachments must: have dimensions at least as large as the corresponding framebuffer dimension * [[VUID-VkFramebufferCreateInfo-pAttachments-00883]] Any given element of pname:pAttachments must: only specify a single mip level * [[VUID-VkFramebufferCreateInfo-pAttachments-00884]] Any given element of pname:pAttachments must: have been created with the identity swizzle * [[VUID-VkFramebufferCreateInfo-width-00885]] pname:width must: be greater than `0`. * [[VUID-VkFramebufferCreateInfo-width-00886]] pname:width must: be less than or equal to sname:VkPhysicalDeviceLimits::pname:maxFramebufferWidth * [[VUID-VkFramebufferCreateInfo-height-00887]] pname:height must: be greater than `0`. * [[VUID-VkFramebufferCreateInfo-height-00888]] pname:height must: be less than or equal to sname:VkPhysicalDeviceLimits::pname:maxFramebufferHeight * [[VUID-VkFramebufferCreateInfo-layers-00889]] pname:layers must: be greater than `0`. * [[VUID-VkFramebufferCreateInfo-layers-00890]] pname:layers must: be less than or equal to sname:VkPhysicalDeviceLimits::pname:maxFramebufferLayers ifdef::VK_KHR_maintenance1[] * [[VUID-VkFramebufferCreateInfo-pAttachments-00891]] Any given element of pname:pAttachments that is a 2D or 2D array image view taken from a 3D image must: not be a depth/stencil format endif::VK_KHR_maintenance1[] **** include::../validity/structs/VkFramebufferCreateInfo.txt[] -- [open,refpage='vkDestroyFramebuffer',desc='Destroy a framebuffer object',type='protos'] -- To destroy a framebuffer, call: include::../api/protos/vkDestroyFramebuffer.txt[] * pname:device is the logical device that destroys the framebuffer. * pname:framebuffer is the handle of the framebuffer to destroy. * pname:pAllocator controls host memory allocation as described in the <> chapter. .Valid Usage **** * [[VUID-vkDestroyFramebuffer-framebuffer-00892]] All submitted commands that refer to pname:framebuffer must: have completed execution * [[VUID-vkDestroyFramebuffer-framebuffer-00893]] If sname:VkAllocationCallbacks were provided when pname:framebuffer was created, a compatible set of callbacks must: be provided here * [[VUID-vkDestroyFramebuffer-framebuffer-00894]] If no sname:VkAllocationCallbacks were provided when pname:framebuffer was created, pname:pAllocator must: be `NULL` **** include::../validity/protos/vkDestroyFramebuffer.txt[] -- [[renderpass-commands]] == Render Pass Commands An application records the commands for a render pass instance one subpass at a time, by beginning a render pass instance, iterating over the subpasses to record commands for that subpass, and then ending the render pass instance. [open,refpage='vkCmdBeginRenderPass',desc='Begin a new render pass',type='protos'] -- To begin a render pass instance, call: include::../api/protos/vkCmdBeginRenderPass.txt[] * pname:commandBuffer is the command buffer in which to record the command. * pname:pRenderPassBegin is a pointer to a slink:VkRenderPassBeginInfo structure (defined below) which indicates the render pass to begin an instance of, and the framebuffer the instance uses. * pname:contents is a elink:VkSubpassContents value specifying how the commands in the first subpass will be provided. After beginning a render pass instance, the command buffer is ready to record the commands for the first subpass of that render pass. .Valid Usage **** * [[VUID-vkCmdBeginRenderPass-initialLayout-00895]] If any of the pname:initialLayout or pname:finalLayout member of the sname:VkAttachmentDescription structures or the pname:layout member of the sname:VkAttachmentReference structures specified when creating the render pass specified in the pname:renderPass member of pname:pRenderPassBegin is ename:VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL then the corresponding attachment image subresource of the framebuffer specified in the pname:framebuffer member of pname:pRenderPassBegin must: have been created with ename:VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT set * [[VUID-vkCmdBeginRenderPass-initialLayout-00896]] If any of the pname:initialLayout or pname:finalLayout member of the sname:VkAttachmentDescription structures or the pname:layout member of the sname:VkAttachmentReference structures specified when creating the render pass specified in the pname:renderPass member of pname:pRenderPassBegin is ename:VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL or ename:VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL then the corresponding attachment image subresource of the framebuffer specified in the pname:framebuffer member of pname:pRenderPassBegin must: have been created with ename:VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT set * [[VUID-vkCmdBeginRenderPass-initialLayout-00897]] If any of the pname:initialLayout or pname:finalLayout member of the sname:VkAttachmentDescription structures or the pname:layout member of the sname:VkAttachmentReference structures specified when creating the render pass specified in the pname:renderPass member of pname:pRenderPassBegin is ename:VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL then the corresponding attachment image subresource of the framebuffer specified in the pname:framebuffer member of pname:pRenderPassBegin must: have been created with ename:VK_IMAGE_USAGE_SAMPLED_BIT or ename:VK_IMAGE_USAGE_INPUT_ATTACHMENT_BIT set * [[VUID-vkCmdBeginRenderPass-initialLayout-00898]] If any of the pname:initialLayout or pname:finalLayout member of the sname:VkAttachmentDescription structures or the pname:layout member of the sname:VkAttachmentReference structures specified when creating the render pass specified in the pname:renderPass member of pname:pRenderPassBegin is ename:VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL then the corresponding attachment image subresource of the framebuffer specified in the pname:framebuffer member of pname:pRenderPassBegin must: have been created with ename:VK_IMAGE_USAGE_TRANSFER_SRC_BIT set * [[VUID-vkCmdBeginRenderPass-initialLayout-00899]] If any of the pname:initialLayout or pname:finalLayout member of the sname:VkAttachmentDescription structures or the pname:layout member of the sname:VkAttachmentReference structures specified when creating the render pass specified in the pname:renderPass member of pname:pRenderPassBegin is ename:VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL then the corresponding attachment image subresource of the framebuffer specified in the pname:framebuffer member of pname:pRenderPassBegin must: have been created with ename:VK_IMAGE_USAGE_TRANSFER_DST_BIT set * [[VUID-vkCmdBeginRenderPass-initialLayout-00900]] If any of the pname:initialLayout members of the sname:VkAttachmentDescription structures specified when creating the render pass specified in the pname:renderPass member of pname:pRenderPassBegin is not ename:VK_IMAGE_LAYOUT_UNDEFINED, then each such pname:initialLayout must: be equal to the current layout of the corresponding attachment image subresource of the framebuffer specified in the pname:framebuffer member of pname:pRenderPassBegin * [[VUID-vkCmdBeginRenderPass-srcStageMask-00901]] The pname:srcStageMask and pname:dstStageMask members of any element of the pname:pDependencies member of slink:VkRenderPassCreateInfo used to create pname:renderpass must: be supported by the capabilities of the queue family identified by the pname:queueFamilyIndex member of the slink:VkCommandPoolCreateInfo used to create the command pool which pname:commandBuffer was allocated from. **** include::../validity/protos/vkCmdBeginRenderPass.txt[] -- [open,refpage='VkRenderPassBeginInfo',desc='Structure specifying render pass begin info',type='structs'] -- The sname:VkRenderPassBeginInfo structure is defined as: include::../api/structs/VkRenderPassBeginInfo.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:renderPass is the render pass to begin an instance of. * pname:framebuffer is the framebuffer containing the attachments that are used with the render pass. * pname:renderArea is the render area that is affected by the render pass instance, and is described in more detail below. * pname:clearValueCount is the number of elements in pname:pClearValues. * pname:pClearValues is an array of slink:VkClearValue structures that contains clear values for each attachment, if the attachment uses a pname:loadOp value of ename:VK_ATTACHMENT_LOAD_OP_CLEAR or if the attachment has a depth/stencil format and uses a pname:stencilLoadOp value of ename:VK_ATTACHMENT_LOAD_OP_CLEAR. The array is indexed by attachment number. Only elements corresponding to cleared attachments are used. Other elements of pname:pClearValues are ignored. pname:renderArea is the render area that is affected by the render pass instance. The effects of attachment load, store and multisample resolve operations are restricted to the pixels whose x and y coordinates fall within the render area on all attachments. The render area extends to all layers of pname:framebuffer. The application must: ensure (using scissor if necessary) that all rendering is contained within the render area, otherwise the pixels outside of the render area become undefined and shader side effects may: occur for fragments outside the render area. The render area must: be contained within the framebuffer dimensions. ifdef::VK_KHX_multiview[] When multiview is enabled, the resolve operation at the end of a subpass applies to all views in the view mask. endif::VK_KHX_multiview[] [NOTE] .Note ==== There may: be a performance cost for using a render area smaller than the framebuffer, unless it matches the render area granularity for the render pass. ==== .Valid Usage **** * [[VUID-VkRenderPassBeginInfo-clearValueCount-00902]] pname:clearValueCount must: be greater than the largest attachment index in pname:renderPass that specifies a pname:loadOp (or pname:stencilLoadOp, if the attachment has a depth/stencil format) of ename:VK_ATTACHMENT_LOAD_OP_CLEAR * [[VUID-VkRenderPassBeginInfo-clearValueCount-00903]] If pname:clearValueCount is not `0`, pname:pClearValues must: be a pointer to an array of pname:clearValueCount valid sname:VkClearValue unions * [[VUID-VkRenderPassBeginInfo-renderPass-00904]] pname:renderPass must: be <> with the pname:renderPass member of the sname:VkFramebufferCreateInfo structure specified when creating pname:framebuffer. **** include::../validity/structs/VkRenderPassBeginInfo.txt[] -- [open,refpage='VkSubpassContents',desc='Specify how commands in the first subpass of a render pass are provided',type='enums'] -- Possible values of flink:vkCmdBeginRenderPass::pname:contents, specifying how the commands in the first subpass will be provided, are: include::../api/enums/VkSubpassContents.txt[] * ename:VK_SUBPASS_CONTENTS_INLINE specifies that the contents of the subpass will be recorded inline in the primary command buffer, and secondary command buffers must: not be executed within the subpass. * ename:VK_SUBPASS_CONTENTS_SECONDARY_COMMAND_BUFFERS specifies that the contents are recorded in secondary command buffers that will be called from the primary command buffer, and flink:vkCmdExecuteCommands is the only valid command on the command buffer until flink:vkCmdNextSubpass or flink:vkCmdEndRenderPass. -- ifdef::VK_KHX_device_group[] [open,refpage='VkDeviceGroupRenderPassBeginInfoKHX',desc='Set the initial device mask and render areas for a render pass instance',type='structs'] -- If the pname:pNext list of slink:VkRenderPassBeginInfo includes a sname:VkDeviceGroupRenderPassBeginInfoKHX structure, then that structure includes a device mask and set of render areas for the render pass instance. The sname:VkDeviceGroupRenderPassBeginInfoKHX structure is defined as: include::../api/structs/VkDeviceGroupRenderPassBeginInfoKHX.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:deviceMask is the device mask for the render pass instance. * pname:deviceRenderAreaCount is the number of elements in the pname:pDeviceRenderAreas array. * pname:pDeviceRenderAreas is an array of structures of type slink:VkRect2D defining the render area for each physical device. The pname:deviceMask serves several purposes. It is an upper bound on the set of physical devices that can: be used during the render pass instance, and the initial device mask when the render pass instance begins. Render pass attachment load, store, and resolve operations only apply to physical devices included in the device mask. Subpass dependencies only apply to the physical devices in the device mask. If pname:deviceRenderAreaCount is not zero, then the elements of pname:pDeviceRenderAreas override the value of slink:VkRenderPassBeginInfo::pname:renderArea, and provide a render area specific to each physical device. These render areas serve the same purpose as slink:VkRenderPassBeginInfo::pname:renderArea, including controlling the region of attachments that are cleared by ename:VK_ATTACHMENT_LOAD_OP_CLEAR and that are resolved into resolve attachments. If this structure is not present, the render pass instance's device mask is the value of slink:VkDeviceGroupCommandBufferBeginInfoKHX::pname:deviceMask. If this structure is not present or if pname:deviceRenderAreaCount is zero, slink:VkRenderPassBeginInfo::pname:renderArea is used for all physical devices. .Valid Usage **** * [[VUID-VkDeviceGroupRenderPassBeginInfoKHX-deviceMask-00905]] pname:deviceMask must: be a valid device mask value * [[VUID-VkDeviceGroupRenderPassBeginInfoKHX-deviceMask-00906]] pname:deviceMask must: not be zero * [[VUID-VkDeviceGroupRenderPassBeginInfoKHX-deviceMask-00907]] pname:deviceMask must: be a subset of the command buffer's initial device mask * [[VUID-VkDeviceGroupRenderPassBeginInfoKHX-deviceRenderAreaCount-00908]] pname:deviceRenderAreaCount must: either be zero or equal to the number of physical devices in the logical device. **** include::../validity/structs/VkDeviceGroupRenderPassBeginInfoKHX.txt[] -- endif::VK_KHX_device_group[] [open,refpage='vkGetRenderAreaGranularity',desc='Returns the granularity for optimal render area',type='protos'] -- To query the render area granularity, call: include::../api/protos/vkGetRenderAreaGranularity.txt[] * pname:device is the logical device that owns the render pass. * pname:renderPass is a handle to a render pass. * pname:pGranularity points to a slink:VkExtent2D structure in which the granularity is returned. The conditions leading to an optimal pname:renderArea are: * the pname:offset.x member in pname:renderArea is a multiple of the pname:width member of the returned slink:VkExtent2D (the horizontal granularity). * the pname:offset.y member in pname:renderArea is a multiple of the pname:height of the returned slink:VkExtent2D (the vertical granularity). * either the pname:offset.width member in pname:renderArea is a multiple of the horizontal granularity or pname:offset.x+pname:offset.width is equal to the pname:width of the pname:framebuffer in the slink:VkRenderPassBeginInfo. * either the pname:offset.height member in pname:renderArea is a multiple of the vertical granularity or pname:offset.y+pname:offset.height is equal to the pname:height of the pname:framebuffer in the slink:VkRenderPassBeginInfo. Subpass dependencies are not affected by the render area, and apply to the entire image subresources attached to the framebuffer. Similarly, pipeline barriers are valid even if their effect extends outside the render area. include::../validity/protos/vkGetRenderAreaGranularity.txt[] -- [open,refpage='vkCmdNextSubpass',desc='Transition to the next subpass of a render pass',type='protos'] -- To transition to the next subpass in the render pass instance after recording the commands for a subpass, call: include::../api/protos/vkCmdNextSubpass.txt[] * pname:commandBuffer is the command buffer in which to record the command. * pname:contents specifies how the commands in the next subpass will be provided, in the same fashion as the corresponding parameter of flink:vkCmdBeginRenderPass. The subpass index for a render pass begins at zero when fname:vkCmdBeginRenderPass is recorded, and increments each time fname:vkCmdNextSubpass is recorded. Moving to the next subpass automatically performs any multisample resolve operations in the subpass being ended. End-of-subpass multisample resolves are treated as color attachment writes for the purposes of synchronization. That is, they are considered to execute in the ename:VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT pipeline stage and their writes are synchronized with ename:VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT. Synchronization between rendering within a subpass and any resolve operations at the end of the subpass occurs automatically, without need for explicit dependencies or pipeline barriers. However, if the resolve attachment is also used in a different subpass, an explicit dependency is needed. After transitioning to the next subpass, the application can: record the commands for that subpass. .Valid Usage **** * [[VUID-vkCmdNextSubpass-None-00909]] The current subpass index must: be less than the number of subpasses in the render pass minus one **** include::../validity/protos/vkCmdNextSubpass.txt[] -- [open,refpage='vkCmdEndRenderPass',desc='End the current render pass',type='protos'] -- To record a command to end a render pass instance after recording the commands for the last subpass, call: include::../api/protos/vkCmdEndRenderPass.txt[] * pname:commandBuffer is the command buffer in which to end the current render pass instance. Ending a render pass instance performs any multisample resolve operations on the final subpass. .Valid Usage **** * [[VUID-vkCmdEndRenderPass-None-00910]] The current subpass index must: be equal to the number of subpasses in the render pass minus one **** include::../validity/protos/vkCmdEndRenderPass.txt[] --