GlPolygonMode

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_glPolygonMode: select a polygon rasterization mode


Syntax

 SUB _glPolygonMode (BYVAL face AS _UNSIGNED LONG, BYVAL mode AS _UNSIGNED LONG)
 void _glPolygonMode(GLenum face, GLenum mode);


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

_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

To draw a surface with outlined polygons, call

<source lang="cpp">

glPolygonMode(, );

</source>


Notes:

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

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


Use With:

_glGet with argument _GL_POLYGON_MODE


See also

SUB _GL _glLineWidth, _glPointSize


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



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