99 lines
4.0 KiB
Plaintext
99 lines
4.0 KiB
Plaintext
[[vertexpostproc-viewportwscaling]]
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== Controlling Viewport W Scaling
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If viewport *W* scaling is enabled, the *W* component of the clip coordinate
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is modified by the provided coefficients from the corresponding viewport as
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follows.
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:: [eq]#w~c~' = x~coeff~ x~c~ {plus} y~coeff~ y~c~ {plus} w~c~#
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[open,refpage='VkPipelineViewportWScalingStateCreateInfoNV',desc='Structure specifying parameters of a newly created pipeline viewport W scaling state',type='structs']
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--
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The sname:VkPipelineViewportWScalingStateCreateInfoNV structure is defined
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as:
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include::../../api/structs/VkPipelineViewportWScalingStateCreateInfoNV.txt[]
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* pname:sType is the type of this structure.
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* pname:pNext is `NULL` or a pointer to an extension-specific structure.
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* pname:viewportWScalingEnable controls whether viewport *W* scaling is
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enabled.
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* pname:viewportCount is the number of viewports used by *W* scaling, and
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must: match the number of viewports in the pipeline if viewport *W*
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scaling is enabled.
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* pname:pViewportWScalings is a pointer to an array of
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sname:VkViewportWScalingNV structures, which define the *W* scaling
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parameters for the corresponding viewport.
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If the viewport *W* scaling state is dynamic, this member is ignored.
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include::../../validity/structs/VkPipelineViewportWScalingStateCreateInfoNV.txt[]
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--
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The sname:VkPipelineViewportWScalingStateCreateInfoNV state is set by adding
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an instance of this structure to the pname:pNext chain of an instance of the
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sname:VkPipelineViewportStateCreateInfo structure and setting the graphics
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pipeline state with flink:vkCreateGraphicsPipelines.
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[open,refpage='vkCmdSetViewportWScalingNV',desc='Set the viewport W scaling on a command buffer',type='protos']
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--
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If the bound pipeline state object was not created with the
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ename:VK_DYNAMIC_STATE_VIEWPORT_W_SCALING_NV dynamic state enabled, viewport
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*W* scaling parameters are specified using the pname:pViewportWScalings
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member of slink:VkPipelineViewportWScalingStateCreateInfoNV in the pipeline
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state object.
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If the pipeline state object was created with the
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ename:VK_DYNAMIC_STATE_VIEWPORT_W_SCALING_NV dynamic state enabled, the
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viewport transformation parameters are dynamically set and changed with the
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command:
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include::../../api/protos/vkCmdSetViewportWScalingNV.txt[]
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* pname:commandBuffer is the command buffer into which the command will be
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recorded.
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* pname:firstViewport is the index of the first viewport whose parameters
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are updated by the command.
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* pname:viewportCount is the number of viewports whose parameters are
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updated by the command.
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* pname:pViewportWScalings is a pointer to an array of
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slink:VkViewportWScalingNV structures specifying viewport parameters.
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The viewport parameters taken from element [eq]#i# of
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pname:pViewportWScalings replace the current state for the viewport index
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[eq]#pname:firstViewport {plus} i#, for [eq]#i# in [eq]#[0,
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pname:viewportCount)#.
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.Valid Usage
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****
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* [[VUID-vkCmdSetViewportWScalingNV-None-01322]]
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The bound graphics pipeline must: have been created with the
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ename:VK_DYNAMIC_STATE_VIEWPORT_W_SCALING_NV dynamic state enabled
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* [[VUID-vkCmdSetViewportWScalingNV-firstViewport-01323]]
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pname:firstViewport must: be less than
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slink:VkPhysicalDeviceLimits::pname:maxViewports
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* [[VUID-vkCmdSetViewportWScalingNV-firstViewport-01324]]
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The sum of pname:firstViewport and pname:viewportCount must: be between
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`1` and slink:VkPhysicalDeviceLimits::pname:maxViewports, inclusive
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****
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include::../../validity/protos/vkCmdSetViewportWScalingNV.txt[]
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--
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Both slink:VkPipelineViewportWScalingStateCreateInfoNV and
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flink:vkCmdSetViewportWScalingNV use sname:VkViewportWScalingNV to set the
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viewport transformation parameters.
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[open,refpage='VkViewportWScalingNV',desc='Structure specifying a viewport',type='structs']
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--
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The sname:VkViewportWScalingNV structure is defined as:
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include::../../api/structs/VkViewportWScalingNV.txt[]
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* pname:xcoeff and pname:ycoeff are the viewport's W scaling factor for x
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and y respectively.
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include::../../validity/structs/VkViewportWScalingNV.txt[]
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--
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