GLSHADEMODEL(3G)						   OpenGL Manual						  GLSHADEMODEL(3G)

NAME

       glShadeModel - select flat or smooth shading

C SPECIFICATION

       void glShadeModel(GLenum mode);

PARAMETERS

       mode
	   Specifies a symbolic value representing a shading technique. Accepted values are GL_FLAT and GL_SMOOTH. The initial value is GL_SMOOTH.

DESCRIPTION

       GL primitives can have either flat or smooth shading. Smooth shading, the default, causes the computed colors of vertices to be
       interpolated as the primitive is rasterized, typically assigning different colors to each resulting pixel fragment. Flat shading selects
       the computed color of just one vertex and assigns it to all the pixel fragments generated by rasterizing a single primitive. In either
       case, the computed color of a vertex is the result of lighting if lighting is enabled, or it is the current color at the time the vertex
       was specified if lighting is disabled.

       Flat and smooth shading are indistinguishable for points. Starting when glBegin() is issued and counting vertices and primitives from 1,
       the GL gives each flat-shaded line segment i the computed color of vertex i + 1, its second vertex. Counting similarly from 1, the GL gives
       each flat-shaded polygon the computed color of the vertex listed in the following table. This is the last vertex to specify the polygon in
       all cases except single polygons, where the first vertex specifies the flat-shaded color.

       +--------------------------------------------------+-----------------------------------+
       |						  |				      |
       |			Primitive Type of Polygon |			     Vertex   |
       |			i			  |				      |
       |						  |				      |
       +--------------------------------------------------+-----------------------------------+
       |Single polygon					  |		    1		      |
       |			(			  |				      |
       |						  |				      |
       |						  |				      |
       |				i		  |				      |
       |				==		  |				      |
       |				1		  |				      |
       |						  |				      |
       |			)			  |				      |
       +--------------------------------------------------+-----------------------------------+
       |Triangle strip					  | i				      |
       |						  |				    + |
       |						  |				    2 |
       +--------------------------------------------------+-----------------------------------+
       |Triangle fan					  | i				      |
       |						  |				    + |
       |						  |				    2 |
       +--------------------------------------------------+-----------------------------------+
       |Independent triangle				  | 3				      |
       |						  |				      |
       |						  |				    i |
       +--------------------------------------------------+-----------------------------------+
       |Quad strip					  | 2				      |
       |						  |				      |
       |						  |				    i |
       |						  |				    + |
       |						  |				    2 |
       +--------------------------------------------------+-----------------------------------+
       |Independent quad				  | 4				      |
       |						  |				      |
       |						  |				    i |
       +--------------------------------------------------+-----------------------------------+

       Flat and smooth shading are specified by glShadeModel with mode set to GL_FLAT and GL_SMOOTH, respectively.

ERRORS

       GL_INVALID_ENUM is generated if mode is any value other than GL_FLAT or GL_SMOOTH.

       GL_INVALID_OPERATION is generated if glShadeModel is executed between the execution of glBegin() and the corresponding execution of
       glEnd().

ASSOCIATED GETS

       glGet() with argument GL_SHADE_MODEL

SEE ALSO

       glBegin(), glColor(), glLight(), glLightModel()

COPYRIGHT

       Copyright (C) 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/.

AUTHORS

       opengl.org

opengl.org							    06/10/2014							  GLSHADEMODEL(3G)