glshademodel(3g) [redhat man page]

GLSHADEMODEL(3G)														  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  interpo-
       lated as the primitive is rasterized, typically assigning different colors to each resulting pixel fragment.  Flat shading selects the com-
       puted 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 speci-
       fied 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 i	Vertex
							  -------------------------------------
							  Single polygon (i==1) 	  1
							  Triangle strip		 i+2
							  Triangle fan			 i+2
							  Independent triangle		  3i
							  Quad strip			 2i+2
							  Independent quad		  4i
							  -------------------------------------

       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(3G), glColor(3G), glLight(3G), glLightModel(3G)

																  GLSHADEMODEL(3G)

GLCOLORMATERIAL(3G)													       GLCOLORMATERIAL(3G)

NAME

       glColorMaterial - cause a material color to track the current color

C SPECIFICATION

       void glColorMaterial( GLenum face,
			     GLenum mode )

PARAMETERS

       face  Specifies	whether  front,  back,	or  both  front  and back material parameters should track the current color.  Accepted values are
	     GL_FRONT, GL_BACK, and GL_FRONT_AND_BACK.	The initial value is GL_FRONT_AND_BACK.

       mode  Specifies which of several material parameters track the current color.  Accepted values  are  GL_EMISSION,  GL_AMBIENT,  GL_DIFFUSE,
	     GL_SPECULAR, and GL_AMBIENT_AND_DIFFUSE.  The initial value is GL_AMBIENT_AND_DIFFUSE.

DESCRIPTION

       glColorMaterial	specifies which material parameters track the current color.  When GL_COLOR_MATERIAL is enabled, the material parameter or
       parameters specified by mode, of the material or materials specified by face, track the current color at all times.

       To enable and disable GL_COLOR_MATERIAL, call glEnable and glDisable with argument GL_COLOR_MATERIAL.  GL_COLOR_MATERIAL is initially  dis-
       abled.

NOTES

       glColorMaterial makes it possible to change a subset of material parameters for each vertex using only the glColor command, without calling
       glMaterial.  If only such a subset of parameters is to be specified for each vertex,  calling  glColorMaterial  is  preferable  to  calling
       glMaterial.

       Call glColorMaterial before enabling GL_COLOR_MATERIAL.

       Calling	glDrawElements, glDrawArrays, or glDrawRangeElements may leave the current color indeterminate, if the color array is enabled.	If
       glColorMaterial is enabled while the current color is indeterminate, the lighting material state specified by face and mode is  also  inde-
       terminate.

       If  the	GL version is 1.1 or greater, and GL_COLOR_MATERIAL is enabled, evaluated color values affect the results of the lighting equation
       as if the current color were being modified, but no change is made to the tracking lighting parameter of the current color.

ERRORS

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

       GL_INVALID_OPERATION is generated if glColorMaterial is executed between the execution of glBegin and the corresponding execution of glEnd.

ASSOCIATED GETS

       glIsEnabled with argument GL_COLOR_MATERIAL
       glGet with argument GL_COLOR_MATERIAL_PARAMETER
       glGet with argument GL_COLOR_MATERIAL_FACE

SEE ALSO

       glColor(3G),   glColorPointer(3G),    glDrawArrays(3G),	  glDrawElements(3G),	 glDrawRangeElements(3G),    glEnable(3G),    glLight(3G),
       glLightModel(3G), glMaterial(3G)

															       GLCOLORMATERIAL(3G)