glPolygonMode

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Select a polygon rasterization mode.

C Specification[edit]

void glPolygonMode( GLenum face, GLenum mode );


Parameters[edit]

face - Specifies the polygons that mode applies to. Must be 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[edit]

 glPolygonMode controls the interpretation of polygons for rasterization. face describes which polygons mode applies to: both front and back-facing polygons ( 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. 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_SMOOTH control the rasterization of the polygon.


Examples[edit]

To draw a surface with outlined polygons, call

glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);



Notes[edit]

Vertices are marked as boundary or nonboundary with an edge flag. Edge flags are generated internally by the GL when it decomposes triangle stips and fans.


Errors[edit]

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


Associated Gets[edit]

 glGet with argument GL_POLYGON_MODE 


Version Support[edit]

 glPolygonMode  2.0+

See Also[edit]

 glLineWidth , glPointSize 


Copyright[edit]

Copyright© 1991-2006 Silicon Graphics, Inc. Copyright© 2010-2014 Khronos Group. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.