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Manual Reference Pages  - GLPOLYGONMODE (3G)

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glPolygonMode - select a polygon rasterization mode

CONTENTS

C Specification
Parameters
Description
Examples
Notes
Errors
Associated Gets
See Also

void glPolygonMode( GLenum face,

                  GLenum mode )

face	Specifies the polygons that mode applies to. Must be  GL_FRONT for front-facing polygons,  GL_BACK for back-facing polygons, or  GL_FRONT_AND_BACK for front- and back-facing polygons.
mode	Specifies how polygons will be rasterized. Accepted values are  GL_POINT,  GL_LINE, and  GL_FILL. The initial value is  GL_FILL for both front- and back-facing polygons.

 glPolygonMode controls the interpretation of polygons for rasterization. face describes which polygons mode applies to: front-facing polygons ( GL_FRONT), back-facing polygons ( GL_BACK), or both ( GL_FRONT_AND_BACK). 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.

Three modes are defined and can be specified in mode:

GL_POINT	Polygon vertices that are marked as the start of a boundary edge are drawn as points. Point attributes such as  GL_POINT_SIZE and  GL_POINT_SMOOTH control the rasterization of the points. Polygon rasterization attributes other than  GL_POLYGON_MODE have no effect.
GL_LINE	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  glLineStipple). Line attributes such as  GL_LINE_WIDTH and  GL_LINE_SMOOTH control the rasterization of the lines. Polygon rasterization attributes other than  GL_POLYGON_MODE have no effect.
GL_FILL	The interior of the polygon is filled. Polygon attributes such as  GL_POLYGON_STIPPLE and  GL_POLYGON_SMOOTH control the rasterization of the polygon.

To draw a surface with filled back-facing polygons and outlined front-facing polygons, call
.Ex 1 glPolygonMode( GL_FRONT,  GL_LINE);
.Ee

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  glEdgeFlag.

 GL_INVALID_ENUM is generated if either face or mode is not an accepted value.

 GL_INVALID_OPERATION is generated if  glPolygonMode is executed between the execution of  glBegin and the corresponding execution of  glEnd.

 glGet with argument  GL_POLYGON_MODE

 glBegin(3G),  glEdgeFlag(3G),  glLineStipple(3G),  glLineWidth(3G),  glPointSize(3G),  glPolygonStipple(3G)

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