GlPolygonMode
_glPolygonMode: select a polygon rasterization mode
Contents
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/.
