113 lines
3.6 KiB
Plaintext
113 lines
3.6 KiB
Plaintext
include::meta/VK_NVX_multiview_per_view_attributes.txt[]
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*Last Modified Date*::
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2017-01-13
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*IP Status*::
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No known IP claims.
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*Interactions and External Dependencies*::
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- This extension requires the
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https://www.khronos.org/registry/spir-v/extensions/NV/SPV_NVX_multiview_per_view_attributes.html[`SPV_NVX_multiview_per_view_attributes`]
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SPIR-V extension.
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- This extension requires the `GL_NVX_multiview_per_view_attributes`
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extension for GLSL source languages.
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- This extension interacts with `<<VK_NV_viewport_array2>>`.
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*Contributors*::
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- Jeff Bolz, NVIDIA
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- Daniel Koch, NVIDIA
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This extension adds a new way to write shaders to be used with multiview
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subpasses, where the attributes for all views are written out by a single
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invocation of the vertex processing stages.
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Related SPIR-V and GLSL extensions `SPV_NVX_multiview_per_view_attributes`
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and `GL_NVX_multiview_per_view_attributes` introduce per-view position and
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viewport mask attributes arrays, and this extension defines how those
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per-view attribute arrays are interpreted by Vulkan.
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Pipelines using per-view attributes may: only execute the vertex processing
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stages once for all views rather than once per-view, which reduces redundant
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shading work.
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A subpass creation flag controls whether the subpass uses this extension.
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A subpass must: either exclusively use this extension or not use it at all.
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Some Vulkan implementations only support the position attribute varying
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between views in the X component.
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A subpass can declare via a second creation flag whether all pipelines
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compiled for this subpass will obey this restriction.
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Shaders that use the new per-view outputs (e.g. code:gl_PositionPerViewNV)
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must: also write the non-per-view output (code:gl_Position), and the values
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written must: be such that `gl_Position =
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gl_PositionPerViewNV[gl_ViewIndex]` for all views in the subpass.
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Implementations are free to either use the per-view outputs or the
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non-per-view outputs, whichever would be more efficient.
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If `<<VK_NV_viewport_array2>>` is not also supported and enabled, the
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per-view viewport mask must: not be used.
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=== New Object Types
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None.
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=== New Enum Constants
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* Extending elink:VkStructureType
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** ename:VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_MULTIVIEW_PER_VIEW_ATTRIBUTES_PROPERTIES_NVX
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* Extending elink:VkSubpassDescriptionFlagBits
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** ename:VK_SUBPASS_DESCRIPTION_PER_VIEW_ATTRIBUTES_BIT_NVX
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** ename:VK_SUBPASS_DESCRIPTION_PER_VIEW_POSITION_X_ONLY_BIT_NVX
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=== New Enums
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None.
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=== New Structures
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* slink:VkPhysicalDeviceMultiviewPerViewAttributesPropertiesNVX
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=== New Functions
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None.
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=== New Built-In Variables
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* <<interfaces-builtin-variables-positionperview,code:PositionPerViewNV>>
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* <<interfaces-builtin-variables-viewportmaskperview,code:ViewportMaskPerViewNV>>
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=== New SPIR-V Capabilities
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* <<spirvenv-capabilities-table-perviewattributes,code:PerViewAttributesNV>>
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=== Issues
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None.
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=== Examples
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[source,c]
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---------------------------------------------------
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#version 450 core
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#extension GL_KHX_multiview : enable
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#extension GL_NVX_multiview_per_view_attributes : enable
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layout(location = 0) in vec4 position;
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layout(set = 0, binding = 0) uniform Block { mat4 mvpPerView[2]; } buf;
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void main()
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{
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// Output both per-view positions and gl_Position as a function
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// of gl_ViewIndex
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gl_PositionPerViewNV[0] = buf.mvpPerView[0] * position;
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gl_PositionPerViewNV[1] = buf.mvpPerView[1] * position;
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gl_Position = buf.mvpPerView[gl_ViewIndex] * position;
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}
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---------------------------------------------------
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=== Version History
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* Revision 1, 2017-01-13 (Jeff Bolz)
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- Internal revisions
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