VkViewport(3)

# VkViewport(3) Manual Page

## Name

VkViewport - Structure specifying a viewport

## C Specification

The `VkViewport` structure is defined as:

    typedef struct VkViewport {
        float    x;
        float    y;
        float    width;
        float    height;
        float    minDepth;
        float    maxDepth;
    } VkViewport;

## Members

- `x` and `y` are the viewport’s upper left corner (x,y).

- `width` and `height` are the viewport’s width and height, respectively.

- `minDepth` and `maxDepth` are the depth range for the viewport. It is valid for `minDepth` to be greater than or equal to `maxDepth`.

## Description

The framebuffer depth coordinate `z`f may be represented using either a fixed-point or floating-point representation. However, a floating-point representation must be used if the depth/stencil attachment has a floating-point depth component. If an m-bit fixed-point representation is used, we assume that it represents each value \(\frac{k}{2^m - 1}\), where k ∈ { 0, 1, …​, 2m-1 }, as k (e.g. 1.0 is represented in binary as a string of all ones).

The viewport parameters shown in the above equations are found from these values as

  ox = `x` + `width` / 2

  oy = `y` + `height` / 2

  oz = `minDepth`

  px = `width`

  py = `height`

  pz = `maxDepth` - `minDepth`.

The application can specify a negative term for `height`, which has the effect of negating the y coordinate in clip space before performing the transform. When using a negative `height`, the application should also adjust the `y` value to point to the lower left corner of the viewport instead of the upper left corner. Using the negative `height` allows the application to avoid having to negate the y component of the `Position` output from the last vertex processing stage in shaders that also target other graphics APIs.

The width and height of the implementation-dependent maximum viewport dimensions must be greater than or equal to the width and height of the largest image which can be created and attached to a framebuffer.

The floating-point viewport bounds are represented with an implementation-dependent precision.

Valid Usage

- `width` must be greater than `0.0`

- `width` must be less than or equal to `VkPhysicalDeviceLimits`::`maxViewportDimensions`[0]

- The absolute value of `height` must be less than or equal to `VkPhysicalDeviceLimits`::`maxViewportDimensions`[1]

- `x` must be greater than or equal to `viewportBoundsRange`[0]

- (`x` + `width`) must be less than or equal to `viewportBoundsRange`[1]

- `y` must be greater than or equal to `viewportBoundsRange`[0]

- `y` must be less than or equal to `viewportBoundsRange`[1]

- (`y` + `height`) must be greater than or equal to `viewportBoundsRange`[0]

- (`y` + `height`) must be less than or equal to `viewportBoundsRange`[1]

- Unless `https://www.khronos.org/registry/vulkan/specs/1.2-extensions/html/vkspec.html#VK_EXT_depth_range_unrestricted` extension is enabled `minDepth` must be between `0.0` and `1.0`, inclusive

- Unless `https://www.khronos.org/registry/vulkan/specs/1.2-extensions/html/vkspec.html#VK_EXT_depth_range_unrestricted` extension is enabled `maxDepth` must be between `0.0` and `1.0`, inclusive

## See Also

VkPipelineViewportStateCreateInfo, vkCmdSetViewport

## Document Notes

For more information, see the Vulkan Specification

This page is extracted from the Vulkan Specification. Fixes and changes should be made to the Specification, not directly.

## Copyright

Copyright (c) 2014-2020 Khronos Group. This work is licensed under a Creative Commons Attribution 4.0 International License.