2010 Khronos Group
glViewportArray 3G
glViewportArray set multiple viewports

## C Specification

void `glViewportArrayv` GLuint first GLsizei count const GLfloat *v

## Parameters

first

  Specify the first viewport to set.

count

  Specify the number of viewports to set.

v

  Specify the address of an array containing the viewport parameters.

## Description

`glViewportArrayv` specifies the parameters for multiple viewports simulataneously. first specifies the index of the first viewport to modify and count specifies the number of viewports to modify. first must be less than the value of `GL_MAX_VIEWPORTS`, and first + count must be less than or equal to the value of `GL_MAX_VIEWPORTS`. Viewports whose indices lie outside the range [first, first + count) are not modified. v contains the address of an array of floating point values specifying the left (x), bottom (y), width (w), and height (h) of each viewport, in that order. x and y give the location of the viewport's lower left corner, and w and h give the width and height of the viewport, respectively. The viewport specifies the affine transformation of x and y from normalized device coordinates to window coordinates. Let x nd y nd be normalized device coordinates. Then the window coordinates x w y w are computed as follows:

x w = x nd + 1 ⁢ width 2 + x

y w = y nd + 1 ⁢ height 2 + y

The location of the viewport's bottom left corner, given by (x, y) is clamped to be within the implementaiton-dependent viewport bounds range. The viewport bounds range [min, max] can be determined by calling glGet with argument `GL_VIEWPORT_BOUNDS_RANGE`. Viewport width and height are silently clamped to a range that depends on the implementation. To query this range, call glGet with argument `GL_MAX_VIEWPORT_DIMS`.

The precision with which the GL interprets the floating point viewport bounds is implementation-dependent and may be determined by querying the impementation-defined constant `GL_VIEWPORT_SUBPIXEL_BITS`.

## Errors

`GL_INVALID_VALUE` is generated if first is greater than or equal to the value of `GL_MAX_VIEWPORTS`.

`GL_INVALID_VALUE` is generated if first + count is greater than or equal to the value of `GL_MAX_VIEWPORTS`.

`GL_INVALID_VALUE` is generated if either width or height is negative.

## Associated Gets

glGet with argument `GL_VIEWPORT`

glGet with argument `GL_MAX_VIEWPORT_DIMS`

glGet with argument `GL_VIEWPORT_BOUNDS_RANGE`

glGet with argument `GL_VIEWPORT_SUBPIXEL_BITS`

## See Also

glDepthRange, glViewport, glViewportIndexed

## Copyright

Copyright 2010 Khronos Group. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1.0, 8 June 1999. http://opencontent.org/openpub/.