GLPOLYGONMODE(3G) GLPOLYGONMODE(3G)
NAME
glPolygonMode - select a polygon rasterization mode
C SPECIFICATION
void glPolygonMode( GLenum face,
GLenum mode )
PARAMETERS
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.
DESCRIPTION
glPolygonMode controls the interpretation of polygons for rasterization. face describes which polygons mode applies to: front-facing poly-
gons (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 ras-
terization of the polygon.
EXAMPLES
To draw a surface with filled back-facing polygons and outlined front-facing polygons, call glPolygonMode(GL_FRONT, GL_LINE);
NOTES
Vertices are marked as boundary or nonboundary with an edge flag. Edge flags are generated internally by the GL when it decomposes poly-
gons; they can be set explicitly using glEdgeFlag.
ERRORS
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.
ASSOCIATED GETS
glGet with argument GL_POLYGON_MODE
SEE ALSO
glBegin, glEdgeFlag, glLineStipple, glLineWidth, glPointSize, glPolygonStipple
GLPOLYGONMODE(3G)