Vulkan-Docs/doc/specs/vulkan/appendices/VK_EXT_blend_operation_advanced.txt
Jon Leech 0cc6bba634 Change log for September 15, 2017 Vulkan 1.0.61 spec update:
* Bump API patch number and header version number to 61 for this update.

Github Issues:

  * Provide alternate length attributes (altlen=) in the XML schema, for
    those using length attributes to generate code instead of documentation
    (public issue 555).
  * Fix erroneous references to `latex:` being used for asciidoc math
    markup, rather than `latexmath:` (public pull request 556).
  * Add author ID to XML for Kazan software renderer (public pull request
    557).

Internal Issues:

  * Add the <<fundamentals-abi,Application Binary Interface>> section
    describing platform ABI requirements and recommendations, add examples
    of function and function pointer declarations to the
    <<boilerplate-platform-specific-calling-conventions, Platform-Specific
    Calling Conventions>> section, and remove related language that existed
    elsewhere in the specification (internal issue 64).
  * Describe where to document valid usage interactions of chained
    structures in the style guide, and fix one case now appearing in
    slink:VkBufferCreateInfo instead of the child
    slink:VkDedicatedAllocationBufferCreateInfoNV structure (internal issue
    715).
  * Add example to the style guide of describing enumerated types which are
    empty when the spec is built without relevant extensions enabled, and
    apply it to existing examples for
    elink:VkDescriptorSetLayoutCreateFlagBits and
    elink:VkSubpassDescriptionFlagBits (internal issue 864).
  * Add a note to the <<fundamentals-validusage-enums, Valid Usage for
    Enumerated Types>> section that the special values suffixed with
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    penalty for copies done in this way, and why the upper copy limit is
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    issue 969).
  * Remove *Status* fields from extension appendices, since they are by
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Other Issues:

  * Update Data Format specification dependency to version 1.2 and change
    references to DF sections accordingly.
  * Update XML to make the pname:pAllocator parameter of
    flink:vkRegisterDeviceEventEXT and flink:vkRegisterDisplayEventEXT in
    the `VK_EXT_display_control` extension as optional.

New Extensions:

  * `VK_KHR_bind_memory2`
  * `VK_KHR_image_format_list`
  * `VK_KHR_maintenance2`
  * `VK_KHR_sampler_ycbcr_conversion`
2017-09-14 22:41:33 -07:00

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include::meta/VK_EXT_blend_operation_advanced.txt[]
*Last Modified Date*::
2017-06-12
*Contributors*::
- Jeff Bolz, NVIDIA
This extension adds a number of "`advanced`" blending operations that can:
be used to perform new color blending operations, many of which are more
complex than the standard blend modes provided by unextended Vulkan.
This extension requires different styles of usage, depending on the level of
hardware support and the feature enable:
- If
slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT::pname:advancedBlendCoherentOperations
is ename:VK_FALSE, the new blending operations are supported, but a
memory dependency must: separate each advanced blend operation on a
given sample.
ename:VK_ACCESS_COLOR_ATTACHMENT_READ_NONCOHERENT_BIT_EXT is used to
synchronize reads using advanced blend operations.
- If
slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT::pname:advancedBlendCoherentOperations
is ename:VK_TRUE, advanced blend operations obey primitive order just
like basic blend operations.
In unextended Vulkan, the set of blending operations is limited, and can: be
expressed very simply.
The ename:VK_BLEND_OP_MIN and ename:VK_BLEND_OP_MAX blend operations simply
compute component-wise minimums or maximums of source and destination color
components.
The ename:VK_BLEND_OP_ADD, ename:VK_BLEND_OP_SUBTRACT, and
ename:VK_BLEND_OP_REVERSE_SUBTRACT modes multiply the source and destination
colors by source and destination factors and either add the two products
together or subtract one from the other.
This limited set of operations supports many common blending operations but
precludes the use of more sophisticated transparency and blending operations
commonly available in many dedicated imaging APIs.
This extension provides a number of new "`advanced`" blending operations.
Unlike traditional blending operations using ename:VK_BLEND_OP_ADD, these
blending equations do not use source and destination factors specified by
elink:VkBlendFactor.
Instead, each blend operation specifies a complete equation based on the
source and destination colors.
These new blend operations are used for both RGB and alpha components; they
must: not be used to perform separate RGB and alpha blending (via different
values of color and alpha elink:VkBlendOp).
These blending operations are performed using premultiplied colors, where
RGB colors can: be considered premultiplied or non-premultiplied by alpha,
according to the pname:srcPremultiplied and pname:dstPremultiplied members
of slink:VkPipelineColorBlendAdvancedStateCreateInfoEXT.
If a color is considered non-premultiplied, the (R,G,B) color components are
multiplied by the alpha component prior to blending.
For non-premultiplied color components in the range eq#[0,1]#, the
corresponding premultiplied color component would have values in the range
eq#[0 {times} A, 1 {times} A]#.
Many of these advanced blending equations are formulated where the result of
blending source and destination colors with partial coverage have three
separate contributions: from the portions covered by both the source and the
destination, from the portion covered only by the source, and from the
portion covered only by the destination.
The blend parameter
slink:VkPipelineColorBlendAdvancedStateCreateInfoEXT::pname:blendOverlap
can: be used to specify a correlation between source and destination pixel
coverage.
If set to ename:VK_BLEND_OVERLAP_CONJOINT_EXT, the source and destination
are considered to have maximal overlap, as would be the case if drawing two
objects on top of each other.
If set to ename:VK_BLEND_OVERLAP_DISJOINT_EXT, the source and destination
are considered to have minimal overlap, as would be the case when rendering
a complex polygon tessellated into individual non-intersecting triangles.
If set to ename:VK_BLEND_OVERLAP_UNCORRELATED_EXT, the source and
destination coverage are assumed to have no spatial correlation within the
pixel.
In addition to the coherency issues on implementations not supporting
pname:advancedBlendCoherentOperations, this extension has several
limitations worth noting.
First, the new blend operations have a limit on the number of color
attachments they can: be used with, as indicated by
slink:VkPhysicalDeviceBlendOperationAdvancedPropertiesEXT::pname:advancedBlendMaxColorAttachments.
Additionally, blending precision may: be limited to 16-bit floating-point,
which may: result in a loss of precision and dynamic range for framebuffer
formats with 32-bit floating-point components, and in a loss of precision
for formats with 12- and 16-bit signed or unsigned normalized integer
components.
=== New Object Types
None.
=== New Enum Constants
* Extending elink:VkStructureType:
** ename:VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_BLEND_OPERATION_ADVANCED_FEATURES_EXT
** ename:VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_BLEND_OPERATION_ADVANCED_PROPERTIES_EXT
** ename:VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_ADVANCED_STATE_CREATE_INFO_EXT
* Extending elink:VkAccessFlagBits:
** ename:VK_ACCESS_COLOR_ATTACHMENT_READ_NONCOHERENT_BIT_EXT
* Extending elink:VkBlendOp:
** ename:VK_BLEND_OP_ZERO_EXT
** ename:VK_BLEND_OP_SRC_EXT
** ename:VK_BLEND_OP_DST_EXT
** ename:VK_BLEND_OP_SRC_OVER_EXT
** ename:VK_BLEND_OP_DST_OVER_EXT
** ename:VK_BLEND_OP_SRC_IN_EXT
** ename:VK_BLEND_OP_DST_IN_EXT
** ename:VK_BLEND_OP_SRC_OUT_EXT
** ename:VK_BLEND_OP_DST_OUT_EXT
** ename:VK_BLEND_OP_SRC_ATOP_EXT
** ename:VK_BLEND_OP_DST_ATOP_EXT
** ename:VK_BLEND_OP_XOR_EXT
** ename:VK_BLEND_OP_MULTIPLY_EXT
** ename:VK_BLEND_OP_SCREEN_EXT
** ename:VK_BLEND_OP_OVERLAY_EXT
** ename:VK_BLEND_OP_DARKEN_EXT
** ename:VK_BLEND_OP_LIGHTEN_EXT
** ename:VK_BLEND_OP_COLORDODGE_EXT
** ename:VK_BLEND_OP_COLORBURN_EXT
** ename:VK_BLEND_OP_HARDLIGHT_EXT
** ename:VK_BLEND_OP_SOFTLIGHT_EXT
** ename:VK_BLEND_OP_DIFFERENCE_EXT
** ename:VK_BLEND_OP_EXCLUSION_EXT
** ename:VK_BLEND_OP_INVERT_EXT
** ename:VK_BLEND_OP_INVERT_RGB_EXT
** ename:VK_BLEND_OP_LINEARDODGE_EXT
** ename:VK_BLEND_OP_LINEARBURN_EXT
** ename:VK_BLEND_OP_VIVIDLIGHT_EXT
** ename:VK_BLEND_OP_LINEARLIGHT_EXT
** ename:VK_BLEND_OP_PINLIGHT_EXT
** ename:VK_BLEND_OP_HARDMIX_EXT
** ename:VK_BLEND_OP_HSL_HUE_EXT
** ename:VK_BLEND_OP_HSL_SATURATION_EXT
** ename:VK_BLEND_OP_HSL_COLOR_EXT
** ename:VK_BLEND_OP_HSL_LUMINOSITY_EXT
** ename:VK_BLEND_OP_PLUS_EXT
** ename:VK_BLEND_OP_PLUS_CLAMPED_EXT
** ename:VK_BLEND_OP_PLUS_CLAMPED_ALPHA_EXT
** ename:VK_BLEND_OP_PLUS_DARKER_EXT
** ename:VK_BLEND_OP_MINUS_EXT
** ename:VK_BLEND_OP_MINUS_CLAMPED_EXT
** ename:VK_BLEND_OP_CONTRAST_EXT
** ename:VK_BLEND_OP_INVERT_OVG_EXT
** ename:VK_BLEND_OP_RED_EXT
** ename:VK_BLEND_OP_GREEN_EXT
** ename:VK_BLEND_OP_BLUE_EXT
=== New Enums
* elink:VkBlendOverlapEXT
=== New Structures
* slink:VkPhysicalDeviceBlendOperationAdvancedFeaturesEXT
* slink:VkPhysicalDeviceBlendOperationAdvancedPropertiesEXT
* slink:VkPipelineColorBlendAdvancedStateCreateInfoEXT
=== New Functions
None.
=== Issues
None.
=== Version History
* Revisions 1-2, 2017-06-12 (Jeff Bolz)
- Internal revisions