2010
Khronos Group
glViewportIndexed
3G
glViewportIndexed
set a specified viewport
C Specification
void glViewportIndexedf
GLuint index
GLfloat x
GLfloat y
GLfloat w
GLfloat h
void glViewportIndexedfv
GLuint index
const GLfloat *v
Parameters
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).
width
height
For glViewportIndexedf, specifies the width and height
of the viewport.
When a GL context is first attached to a window,
width and height 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:
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 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,
glViewportArray
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/.