73 lines
1.8 KiB
Plaintext
73 lines
1.8 KiB
Plaintext
|
'\" e
|
||
|
|
'\"! eqn | mmdoc
|
||
|
|
'\"macro stdmacro
|
||
|
|
.ds Vn Version 1.2
|
||
|
|
.ds Dt 24 September 1999
|
||
|
|
.ds Re Release 1.2.1
|
||
|
|
.ds Dp Jan 14 18:30
|
||
|
|
.ds Dm 01 viewport.
|
||
|
|
.ds Xs 35742 4 viewport.gl
|
||
|
|
.TH GLVIEWPORT 3G
|
||
|
|
.SH NAME
|
||
|
|
.B "glViewport
|
||
|
|
\- set the viewport
|
||
|
|
|
||
|
|
.SH C SPECIFICATION
|
||
|
|
void \f3glViewport\fP(
|
||
|
|
GLint \fIx\fP,
|
||
|
|
.nf
|
||
|
|
.ta \w'\f3void \fPglViewport( 'u
|
||
|
|
GLint \fIy\fP,
|
||
|
|
GLsizei \fIwidth\fP,
|
||
|
|
GLsizei \fIheight\fP )
|
||
|
|
.fi
|
||
|
|
|
||
|
|
.EQ
|
||
|
|
delim $$
|
||
|
|
.EN
|
||
|
|
.SH PARAMETERS
|
||
|
|
.TP \w'\f2x\fP\ \f2y\fP\ \ 'u
|
||
|
|
\f2x\fP, \f2y\fP
|
||
|
|
Specify the lower left corner of the viewport rectangle,
|
||
|
|
in pixels. The initial value is (0,0).
|
||
|
|
.TP
|
||
|
|
\f2width\fP, \f2height\fP
|
||
|
|
Specify the width and height
|
||
|
|
of the viewport.
|
||
|
|
When a GL context is first attached to a window,
|
||
|
|
\f2width\fP and \f2height\fP are set to the dimensions of that window.
|
||
|
|
.SH DESCRIPTION
|
||
|
|
\%\f3glViewport\fP 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:
|
||
|
|
.sp
|
||
|
|
.ce
|
||
|
|
.EQ
|
||
|
|
x sub w ~=~ ( x sub nd ~+~ 1 ) left ( "width" over 2 right ) ~+~ "x"
|
||
|
|
.EN
|
||
|
|
.sp
|
||
|
|
.ce
|
||
|
|
.EQ
|
||
|
|
y sub w ~=~ ( y sub nd ~+~ 1 ) left ( "height" over 2 right ) ~+~ "y"
|
||
|
|
.EN
|
||
|
|
.RE
|
||
|
|
.P
|
||
|
|
Viewport width and height are silently clamped
|
||
|
|
to a range that depends on the implementation.
|
||
|
|
To query this range, call \%\f3glGet\fP with argument
|
||
|
|
\%\f3GL_MAX_VIEWPORT_DIMS\fP.
|
||
|
|
.SH ERRORS
|
||
|
|
\%\f3GL_INVALID_VALUE\fP is generated if either \f2width\fP or \f2height\fP is negative.
|
||
|
|
.P
|
||
|
|
\%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glViewport\fP
|
||
|
|
is executed between the execution of \%\f3glBegin\fP
|
||
|
|
and the corresponding execution of \%\f3glEnd\fP.
|
||
|
|
.bp
|
||
|
|
.SH ASSOCIATED GETS
|
||
|
|
\%\f3glGet\fP with argument \%\f3GL_VIEWPORT\fP
|
||
|
|
.br
|
||
|
|
\%\f3glGet\fP with argument \%\f3GL_MAX_VIEWPORT_DIMS\fP
|
||
|
|
.SH SEE ALSO
|
||
|
|
\%\f3glDepthRange(3G)\fP
|