104 lines
3.0 KiB
Plaintext
104 lines
3.0 KiB
Plaintext
// Copyright (c) 2014-2018 Khronos Group. This work is licensed under a
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// Creative Commons Attribution 4.0 International License; see
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// http://creativecommons.org/licenses/by/4.0/
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include::meta/VK_KHR_incremental_present.txt[]
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*Last Modified Date*::
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2016-11-02
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*IP Status*::
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No known IP claims.
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*Contributors*::
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- Ian Elliott, Google
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- Jesse Hall, Google
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- Alon Or-bach, Samsung
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- James Jones, NVIDIA
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- Daniel Rakos, AMD
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- Ray Smith, ARM
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- Mika Isojarvi, Google
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- Jeff Juliano, NVIDIA
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- Jeff Bolz, NVIDIA
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This device extension extends slink:vkQueuePresentKHR, from the
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`<<VK_KHR_swapchain>>` extension, allowing an application to specify a list
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of rectangular, modified regions of each image to present.
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This should be used in situations where an application is only changing a
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small portion of the presentable images within a swapchain, since it enables
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the presentation engine to avoid wasting time presenting parts of the
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surface that haven't changed.
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This extension is leveraged from the +EGL_KHR_swap_buffers_with_damage+
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extension.
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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_PRESENT_REGIONS_KHR
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=== New Enums
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None.
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=== New Structures
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* slink:VkRectLayerKHR
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* slink:VkPresentRegionKHR
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* slink:VkPresentRegionsKHR
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=== New Functions
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None.
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=== Examples
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None.
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=== Issues
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1) How should we handle steroescopic-3D swapchains? We need to add a layer
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for each rectangle.
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One approach is to create another struct that contains the slink:VkRect2D
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plus layer, and have slink:VkPresentRegionsKHR point to an array of that
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struct.
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Another approach is to have two parallel arrays, ptext:pRectangles and
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ptext:pLayers, where ptext:pRectangles[i] and ptext:pLayers[i] must be used
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together.
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Which approach should we use, and if the array of a new structure, what
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should that be called?
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*RESOLVED*: Create a new structure, which is a slink:VkRect2D plus a layer,
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and will be called slink:VkRectLayerKHR.
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2) Where is the origin of the slink:VkRectLayerKHR?
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*RESOLVED*: The upper left corner of the presentable image(s) of the
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swapchain, per the definition of framebuffer coordinates.
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3) Does the rectangular region, slink:VkRectLayerKHR, specify pixels of the
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swapchain's image(s), or of the surface?
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*RESOLVED*: Of the image(s).
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Some presentation engines may scale the pixels of a swapchain's image(s) to
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the size of the surface.
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The size of the swapchain's image(s) will be consistent, where the size of
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the surface may vary over time.
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4) What if all of the rectangles for a given swapchain contain a width
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and/or height of zero?
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*RESOLVED*: The application is indicating that no pixels changed since the
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last present.
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The presentation engine may use such a hint and not update any pixels for
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the swapchain.
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However, all other semantics of flink:vkQueuePresentKHR must still be
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honored, including waiting for semaphores to signal.
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=== Version History
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* Revision 1, 2016-11-02 (Ian Elliott)
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- Internal revisions
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