'\" e '\"macro stdmacro .ds Vn Version 1.2 .ds Dt 24 September 1999 .ds Re Release 1.2.1 .ds Dp May 22 14:46 .ds Dm 7 May 22 14: .ds Xs 35742 4 .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\fP