Страницы справочника OS X

Эта страница руководства является частью версии 5.0 Инструментов XCode

Читать страницы руководства

GLPOLYGONOFFSET(3G)                                                                      GLPOLYGONOFFSET(3G)



NAME
       glPolygonOffset - set the scale and units used to calculate depth values


C SPECIFICATION
       void glPolygonOffset( GLfloat factor,
                             GLfloat units )


PARAMETERS
       factor  Specifies a scale factor that is used to create a variable depth offset for each polygon. The
               initial value is 0.

       units   Is multiplied by an implementation-specific value to create a constant depth offset. The ini-tial initial
               tial value is 0.

DESCRIPTION
       When  GL_POLYGON_OFFSET_FILL,  GL_POLYGON_OFFSET_LINE,  or  GL_POLYGON_OFFSET_POINT  is enabled, each
       fragment's depth value will be offset after it is interpolated from the depth values of the appropri-ate appropriate
       ate  vertices.   The  value  of  the  offset is factor*DZ + r*units, where DZ is a measurement of the
       change in depth relative to the screen area of the polygon, and r is the smallest value that is guar-anteed guaranteed
       anteed  to  produce  a  resolvable offset for a given implementation.  The offset is added before the
       depth test is performed and before the value is written into the depth buffer.

       glPolygonOffset is useful for rendering hidden-line images, for applying decals to surfaces, and  for
       rendering solids with highlighted edges.

NOTES
       glPolygonOffset is available only if the GL version is 1.1 or greater.

       glPolygonOffset has no effect on depth coordinates placed in the feedback buffer.

       glPolygonOffset has no effect on selection.

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

ASSOCIATED GETS
       glIsEnabled with argument GL_POLYGON_OFFSET_FILL, GL_POLYGON_OFFSET_LINE, or GL_POLYGON_OFFSET_POINT.

       glGet with argument GL_POLYGON_OFFSET_FACTOR or GL_POLYGON_OFFSET_UNITS.

SEE ALSO
       glDepthFunc(3G), glEnable(3G), glGet(3G), glIsEnabled(3G)




                                                                                         GLPOLYGONOFFSET(3G)