MirOS Manual: glPolygonOffset(3)


GLPOLYGONOFFSET(3G) UNIX Programmer's Manual  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 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 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 exe-
     cuted between the execution of glBegin and the corresponding
     execution of glEnd.

MirOS BSD #10-current  Printed 03.04.2017                       1

GLPOLYGONOFFSET(3G) UNIX Programmer's Manual  GLPOLYGONOFFSET(3G)

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)

MirOS BSD #10-current  Printed 03.04.2017                       2

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