Vulkan-Docs/doc/specs/vulkan/appendices/VK_KHR_shader_draw_parameters.txt
Jon Leech b7b1c3a65d Change log for January 5, 2018 Vulkan 1.0.67 spec update:
* Bump API patch number and header version number to 67 for this update.
  * Update copyright dates to 2018

Github Issues:

  * Fix texture lookup functions in `GL_KHR_vulkan_glsl` specification
    (public pull request 363).
  * Clarify the state waited semaphores are left in when a call to
    flink:vkQueuePresentKHR fails (public issue 572).
  * Cleanup descriptions of slink:VkObjectTablePushConstantEntryNVX and
    slink:VkObjectTableDescriptorSetEntryNVX (public issue 583)
  * Remove redundant flink:vkCmdSetDiscardRectangleEXT valid usage
    statements (public pull 586).
  * Make dynamic state array length valid usage statements implicit for
    flink:vkCmdSetViewportWScalingNV, flink:vkCmdSetDiscardRectangleEXT, and
    flink:vkCmdSetViewport (public pull 589).
  * Clarify meaning of window extent (0,0) in slink:VkSwapchainKHR for the
    Windows and X11 platforms, in their respective extensions (public issue
    590).
  * Allow flink:vkGetPastPresentationTimingGOOGLE to return
    ename:VK_INCOMPLETE (public issue 604).
  * Add synchronization valid usage statements to flink:vkAcquireNextImage
    (public pull 611).
  * Fix some broken external links and internal xrefs (public pull 613).
  * Clean up slink:VkViewport valid usage statements in the presence or
    absence of relevant extensions (public pull 623).
  * Remove
    ename:VK_IMAGE_LAYOUT_DEPTH_READ_ONLY_STENCIL_ATTACHMENT_OPTIMAL_KHR
    token from VK_KHR_maintenance2 from the non-extension VU path for
    slink:VkGraphicsPipelineCreateInfo (public issue 628).
  * Miscellaneous minor markup fixes - extension name strings (public pull
    631), Notes (pull 633), queue names emitted by generator scripts (pull
    634), block formatting in slink:VkDescriptorUpdateTemplateEntryKHR (pull
    635), ename:VK_FORMAT_FEATURE_SAMPLED_IMAGE_FILTER_CUBIC_BIT_IMG (pull
    641), quotes and apostrophes (pull 643),
  * Miscellaneous minor grammar fixes (public pull 644).
  * Fix markup macros so usage like ptext:*Src* works (public pull 647).

Internal Issues:

  * Clarify in the `VK_KHR_surface` and `VK_KHR_swapchain` extensions that
    parameter combinations which aren't supported for normal images are also
    unsupported for presentable images, even if the parameter values are
    individually supported as reported by the surface capability queries
    (internal issue 1029).
  * Fixed XML typo in the valid value field of the pname:sType member of
    slink:VkPhysicalDeviceExternalMemoryHostPropertiesEXT (internal issue
    1100).

Other Issues:

  * Add memory semantics validity rules to the <<spirvenv-module-validation,
    Validation Rules within a Module>> section of the SPIR-V environment
    appendix, and specify that sequentiality consistency is not supported.
    This forbids certain cases like "`Load+Release`" that we don't expect to
    ever be meaningful.
  * Document mapping of OpenGL Shading Language barriers to SPIR-V scope and
    semantics in the `GL_KHR_vulkan_glsl` specification.

New Extensions:

  * `VK_EXT_conservative_rasterization`
2018-01-05 17:39:15 -08:00

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// Copyright (c) 2016-2018 Khronos Group. This work is licensed under a
// Creative Commons Attribution 4.0 International License; see
// http://creativecommons.org/licenses/by/4.0/
include::meta/VK_KHR_shader_draw_parameters.txt[]
*Last Modified Date*::
2016-10-05
*IP Status*::
No known IP claims.
*Interactions and External Dependencies*::
- Requires the
https://www.khronos.org/registry/spir-v/extensions/KHR/SPV_KHR_shader_draw_parameters.html[+SPV_KHR_shader_draw_parameters+]
SPIR-V extension.
- Requires
https://www.khronos.org/registry/OpenGL/extensions/ARB/ARB_shader_draw_parameters.txt[+GL_ARB_shader_draw_parameters+]
for GLSL source languages.
*Contributors*::
- Daniel Koch, NVIDIA Corporation
- Jeff Bolz, NVIDIA
- Daniel Rakos, AMD
- Jan-Harald Fredriksen, ARM
- John Kessenich, Google
- Stuart Smith, IMG
This extension adds support for the following SPIR-V extension in Vulkan:
* +SPV_KHR_shader_draw_parameters+
The extension provides access to three additional built-in shader variables
in Vulkan:
* code:BaseInstance, which contains the pname:firstInstance parameter
passed to draw commands,
* code:BaseVertex, which contains the pname:firstVertex/pname:vertexOffset
parameter passed to draw commands, and
* code:DrawIndex, which contains the index of the draw call currently
being processed from an indirect draw call.
When using GLSL source-based shader languages, the following variables from
+GL_ARB_shader_draw_parameters+ can map to these SPIR-V built-in
decorations:
* `in int gl_BaseInstanceARB;` -> code:BaseInstance,
* `in int gl_BaseVertexARB;` -> code:BaseVertex, and
* `in int gl_DrawIDARB;` -> code:DrawIndex.
=== New Object Types
None.
=== New Enum Constants
None.
=== New Enums
None.
=== New Structures
None.
=== New Functions
None.
=== New Built-In Variables
* <<interfaces-builtin-variables-baseinstance,code:BaseInstance>>
* <<interfaces-builtin-variables-basevertex,code:BaseVertex>>
* <<interfaces-builtin-variables-drawindex,code:DrawIndex>>
=== New SPIR-V Capabilities
* <<spirvenv-capabilities-table-drawparameters,DrawParameters>>
=== Issues
1) Is this the same functionality as +GL_ARB_shader_draw_parameters+?
*RESOLVED*: It's actually a superset as it also adds in support for arrayed
drawing commands.
In GL for +GL_ARB_shader_draw_parameters+, code:gl_BaseVertexARB holds the
integer value passed to the parameter to the command that resulted in the
current shader invocation.
In the case where the command has no code:baseVertex parameter, the value of
code:gl_BaseVertexARB is zero.
This means that code:gl_BaseVertexARB = code:baseVertex (for
code:glDrawElements commands with code:baseVertex) or 0.
In particular there are no code:glDrawArrays commands that take a
code:baseVertex parameter.
Now in Vulkan, we have code:BaseVertex = pname:vertexOffset (for indexed
drawing commands) or pname:firstVertex (for arrayed drawing commands), and
so Vulkan's version is really a superset of GL functionality.
=== Version History
* Revision 1, 2016-10-05 (Daniel Koch)
- Internal revisions