glShadeModel — select flat or smooth shading
void glShadeModel( | GLenum | mode) ; |
mode
Specifies a symbolic value representing a shading technique.
Accepted values are GL_FLAT
and GL_SMOOTH
.
The initial value is GL_SMOOTH
.
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
Primitive Type of Polygon
| Vertex |
---|---|
Single polygon
( | 1 |
Triangle strip |
|
Triangle fan |
|
Independent triangle |
|
Quad strip |
|
Independent quad |
|
Flat and smooth shading are specified by glShadeModel
with mode
set to
GL_FLAT
and GL_SMOOTH
, respectively.
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.
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