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 appropriate
       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 re‐
       solvable  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  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.

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, glEnable, glGet, glIsEnabled

                                                            GLPOLYGONOFFSET(3G)