NAME
glViewport
- set the viewport
C SPECIFICATION
void ggllVViieewwppoorrtt(
GLint _x,
GLint _y,
GLsizei _w_i_d_t_h,
GLsizei _h_e_i_g_h_t )
delim $$
PARAMETERS
-
_x, _y
-
Specify the lower left corner of the viewport rectangle,
in pixels. The initial value is (0,0).
-
_w_i_d_t_h, _h_e_i_g_h_t
-
Specify the width and height
of the viewport.
When a GL context is first attached to a window,
_w_i_d_t_h and _h_e_i_g_h_t are set to the dimensions of that window.
DESCRIPTION
ggllVViieewwppoorrtt specifies the affine transformation of $x$ and $y$ from
normalized device coordinates to window coordinates.
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 ggllGGeett with argument
GGLL__MMAAXX__VVIIEEWWPPOORRTT__DDIIMMSS.
ERRORS
GGLL__IINNVVAALLIIDD__VVAALLUUEE is generated if either _w_i_d_t_h or _h_e_i_g_h_t is negative.
GGLL__IINNVVAALLIIDD__OOPPEERRAATTIIOONN is generated if ggllVViieewwppoorrtt
is executed between the execution of ggllBBeeggiinn
and the corresponding execution of ggllEEnndd.
ASSOCIATED GETS
ggllGGeett with argument GGLL__VVIIEEWWPPOORRTT
ggllGGeett with argument GGLL__MMAAXX__VVIIEEWWPPOORRTT__DDIIMMSS
SEE ALSO
ggllDDeepptthhRRaannggee((33GG))