124 lines
3.7 KiB
Plaintext
124 lines
3.7 KiB
Plaintext
[[VK_AMD_rasterization_order]]
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== VK_AMD_rasterization_order
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*Name String*::
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+VK_AMD_rasterization_order+
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*Extension Type*::
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Device extension
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*Registered Extension Number*::
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19
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*Last Modified Date*::
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2016-04-25
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*Revision*::
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1
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*IP Status*::
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No known IP claims.
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*Dependencies*::
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- This extension is written against version 1.0.11 of the Vulkan API.
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*Contributors*::
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- Matthaeus G.
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Chajdas, AMD
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- Jaakko Konttinen, AMD
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- Daniel Rakos, AMD
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- Graham Sellers, AMD
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- Dominik Witczak, AMD
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*Contacts*::
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- Daniel Rakos, AMD
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This extension introduces the possibility for the application to control the
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order of primitive rasterization.
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In unextended Vulkan, the following stages are guaranteed to execute in _API
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order_:
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* depth bounds test
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* stencil test, stencil op, and stencil write
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* depth test and depth write
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* occlusion queries
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* blending, logic op, and color write
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This extension enables applications to opt into a relaxed, implementation
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defined primitive rasterization order that may allow better parallel
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processing of primitives and thus enabling higher primitive throughput.
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It is applicable in cases where the primitive rasterization order is known
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to not affect the output of the rendering or any differences caused by a
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different rasterization order are not a concern from the point of view of
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the application's purpose.
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A few examples of cases when using the relaxed primitive rasterization order
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would not have an effect on the final rendering:
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* If the primitives rendered are known to not overlap in framebuffer
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space.
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* If depth testing is used with a comparison operator of
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ename:VK_COMPARE_OP_LESS, ename:VK_COMPARE_OP_LESS_OR_EQUAL,
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ename:VK_COMPARE_OP_GREATER, or ename:VK_COMPARE_OP_GREATER_OR_EQUAL,
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and the primitives rendered are known to not overlap in clip space.
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* If depth testing is not used and blending is enabled for all attachments
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with a commutative blend operator.
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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_PIPELINE_RASTERIZATION_STATE_RASTERIZATION_ORDER_AMD
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=== New Enums
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* elink:VkRasterizationOrderAMD
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=== New Structures
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* slink:VkPipelineRasterizationStateRasterizationOrderAMD
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=== New Functions
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None
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=== Issues
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1) How is this extension useful to application developers?
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RESOLVED: Allows them to increase primitive throughput for cases when
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strict API order rasterization is not important due to the nature of the
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content, the configuration used, or the requirements towards the output
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of the rendering.
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2) How does this extension interact with content optimizations aiming to
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reduce overdraw by appropriately ordering the input primitives?
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RESOLVED: While the relaxed rasterization order might somewhat limit the
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effectiveness of such content optimizations, most of the benefits of it
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are expected to be retained even when the relaxed rasterization order is
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used so applications are still recommended to apply these optimizations
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even if they intend to use the extension.
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3) Are there any guarantees about the primitive rasterization order when
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using the new relaxed mode?
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RESOLVED: No.
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The rasterization order is completely implementation dependent in this
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case but in practice it is expected to partially still follow the order
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of incoming primitives.
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4) Does the new relaxed rasterization order have any adverse effect on
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repeatability and other invariance rules of the API?
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RESOLVED: Yes, in the sense that it extends the list of exceptions when
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the repeatability requirement does not apply.
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=== Examples
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None
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=== Issues
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None
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=== Version History
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* Revision 1, 2016-04-25 (Daniel Rakos)
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- Initial draft.
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