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'\" 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 polygonmo
.ds Xs 24991 5 polygonmode.gl
.TH GLPOLYGONMODE 3G
.SH NAME
.B "glPolygonMode
\- select a polygon rasterization mode
.SH C SPECIFICATION
void \f3glPolygonMode\fP(
GLenum \fIface\fP,
.nf
.ta \w'\f3void \fPglPolygonMode( 'u
GLenum \fImode\fP )
.fi
.SH PARAMETERS
.TP \w'\f2face\fP\ \ 'u
\f2face\fP
Specifies the polygons that \f2mode\fP applies to.
Must be
\%\f3GL_FRONT\fP for front-facing polygons,
\%\f3GL_BACK\fP for back-facing polygons,
or \%\f3GL_FRONT_AND_BACK\fP for front- and back-facing polygons.
.TP
\f2mode\fP
Specifies how polygons will be rasterized.
Accepted values are
\%\f3GL_POINT\fP,
\%\f3GL_LINE\fP, and
\%\f3GL_FILL\fP.
The initial value is \%\f3GL_FILL\fP for both front- and back-facing polygons.
.SH DESCRIPTION
\%\f3glPolygonMode\fP controls the interpretation of polygons for rasterization.
\f2face\fP describes which polygons \f2mode\fP applies to:
front-facing polygons (\%\f3GL_FRONT\fP),
back-facing polygons (\%\f3GL_BACK\fP),
or both (\%\f3GL_FRONT_AND_BACK\fP).
The polygon mode affects only the final rasterization of polygons.
In particular,
a polygon's vertices are lit and
the polygon is clipped and possibly culled before these modes are applied.
.P
Three modes are defined and can be specified in \f2mode\fP:
.TP 14
\%\f3GL_POINT\fP
Polygon vertices that are marked as the start of a boundary edge
are drawn as points.
Point attributes such as
\%\f3GL_POINT_SIZE\fP and
\%\f3GL_POINT_SMOOTH\fP control
the rasterization of the points.
Polygon rasterization attributes other than \%\f3GL_POLYGON_MODE\fP have no effect.
.TP
\%\f3GL_LINE\fP
Boundary edges of the polygon are drawn as line segments.
They are treated as connected line segments for line stippling;
the line stipple counter and pattern are not reset between segments
(see \%\f3glLineStipple\fP).
Line attributes such as
\%\f3GL_LINE_WIDTH\fP and
\%\f3GL_LINE_SMOOTH\fP control
the rasterization of the lines.
Polygon rasterization attributes other than \%\f3GL_POLYGON_MODE\fP have no effect.
.TP
\%\f3GL_FILL\fP
The interior of the polygon is filled.
Polygon attributes such as
\%\f3GL_POLYGON_STIPPLE\fP and
\%\f3GL_POLYGON_SMOOTH\fP control the rasterization of the polygon.
.SH EXAMPLES
To draw a surface with filled back-facing polygons
and outlined front-facing polygons,
call
.Ex 1
glPolygonMode(\%\f3GL_FRONT\fP, \%\f3GL_LINE\fP);
.Ee
.SH NOTES
Vertices are marked as boundary or nonboundary with an edge flag.
Edge flags are generated internally by the GL when it decomposes
polygons; they can be set explicitly using \%\f3glEdgeFlag\fP.
.SH ERRORS
\%\f3GL_INVALID_ENUM\fP is generated if either \f2face\fP or \f2mode\fP is not
an accepted value.
.P
\%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glPolygonMode\fP
is executed between the execution of \%\f3glBegin\fP
and the corresponding execution of \%\f3glEnd\fP.
.SH ASSOCIATED GETS
\%\f3glGet\fP with argument \%\f3GL_POLYGON_MODE\fP
.SH SEE ALSO
\%\f3glBegin(3G)\fP,
\%\f3glEdgeFlag(3G)\fP,
\%\f3glLineStipple(3G)\fP,
\%\f3glLineWidth(3G)\fP,
\%\f3glPointSize(3G)\fP,
\%\f3glPolygonStipple(3G)\fP
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