GLVIEWPORT() MachTen Programmer’s Manual GLVIEWPORT()

NAME
glViewport - set the viewport

C SPECIFICATION
void glViewport( GLint x,
GLint y,
GLsizei width,
GLsizei height )

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PARAMETERS
x, y Specify the lower left corner of the viewport rectan-
gle, in pixels. The initial value is (0,0).

width, height
Specify 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.

DESCRIPTION
glViewport specifies the affine transformation of $x$ and
$y$ from normalized device coordinates to window coordi-
nates. Let ($x sub nd$, $y sub nd$) be normalized device
coordinates. Then the window coordinates ($x sub w$, $y
sub w$) are computed as follows:

x sub w ~=~ ( x sub nd + 1 ) left ( "width" over 2 right )
~+~ "x"

y sub w ~=~ ( y sub nd + 1 ) left ( "height" over 2 right
) ~+~ "y"

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.

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

GL_INVALID_OPERATION is generated if glViewport is exe-
cuted between the execution of glBegin and the correspond-
ing execution of glEnd.

ASSOCIATED GETS
glGet with argument GL_VIEWPORT
glGet with argument GL_MAX_VIEWPORT_DIMS