1GLFRONTFACE(3G) GLFRONTFACE(3G)
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6 glFrontFace - define front- and back-facing polygons
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10 void glFrontFace( GLenum mode )
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14 mode Specifies the orientation of front-facing polygons. GL_CW and
15 GL_CCW are accepted. The initial value is GL_CCW.
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18 In a scene composed entirely of opaque closed surfaces, back-facing
19 polygons are never visible. Eliminating these invisible polygons has
20 the obvious benefit of speeding up the rendering of the image. To
21 enable and disable elimination of back-facing polygons, call glEnable
22 and glDisable with argument GL_CULL_FACE.
23 The projection of a polygon to window coordinates is said to have
25 clockwise winding if an imaginary object following the path from its
26 first vertex, its second vertex, and so on, to its last vertex, and
27 finally back to its first vertex, moves in a clockwise direction about
28 the interior of the polygon. The polygon's winding is said to be coun‐
29 terclockwise if the imaginary object following the same path moves in a
30 counterclockwise direction about the interior of the polygon.
31 glFrontFace specifies whether polygons with clockwise winding in window
32 coordinates, or counterclockwise winding in window coordinates, are
33 taken to be front-facing. Passing GL_CCW to mode selects counterclock‐
34 wise polygons as front-facing; GL_CW selects clockwise polygons as
35 front-facing. By default, counterclockwise polygons are taken to be
36 front-facing.
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39 GL_INVALID_ENUM is generated if mode is not an accepted value.
40 GL_INVALID_OPERATION is generated if glFrontFace is executed between
42 the execution of glBegin and the corresponding execution of glEnd.
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45 glGet with argument GL_FRONT_FACE
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48 glCullFace(3G), glLightModel(3G)
49 GLFRONTFACE(3G)