glViewportIndexed

set a specified viewport

Signature

glViewportIndexed( )->
glViewportIndexedf( GLuint ( index ) , GLfloat ( x ) , GLfloat ( y ) , GLfloat ( w ) , GLfloat ( h ) )-> void
glViewportIndexedf( index , x , y , w , h )
glViewportIndexedfv( GLuint ( index ) , const GLfloat *( v ) )-> void
glViewportIndexedfv( index , v )

Parameters

VariablesDescription
index
Specify the first viewport to set.
x, y
For glViewportIndexedf , specifies the lower left corner of the viewport rectangle, in pixels. The initial value is (0,0).
w, h
For glViewportIndexedf , specifies the width and height of the viewport. When a GL context is first attached to a window, w and h are set to the dimensions of that window.
v
For glViewportIndexedfv , specifies the address of an array containing the viewport parameters.

Description

glViewportIndexedf and glViewportIndexedfv specify the parameters for a single viewport. index specifies the index of the viewport to modify. index must be less than the value of GL_MAX_VIEWPORTS . For glViewportIndexedf , x , y , w , and h specify the left, bottom, width and height of the viewport in pixels, respectively. For glViewportIndexedfv , 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 .
Calling glViewportIndexedfv is equivalent to calling glViewportArray with first set to index , count set to 1 and v passsed directly. glViewportIndexedf is equivalent to:
void glViewportIndexedf(GLuint index, GLfloat x, GLfloat y, GLfloat w, GLfloat h) { const float v[4] = { x, y, w, h }; glViewportArrayv(index, 1, v); }

Errors

GL_INVALID_VALUE is generated if index is greater than or equal to the value of GL_MAX_VIEWPORTS .
GL_INVALID_VALUE is generated if either w or h 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

Version Support

glViewportIndexedf
glViewportIndexedfv

See Also

Copyright

Copyright
2010-2014 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. .

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