C SPECIFICATION

       void GLAPIENTRY 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 initial 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  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 guaranteed 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  apply-
       ing  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 feed-
       back 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.

SEE ALSO

       glDepthFunc, glEnable, glGet, glIsEnabled



                                                           GLPOLYGONOFFSET(3G)