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.
MirBSD #10-current Printed 2021-12-07 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)
MirBSD #10-current Printed 2021-12-07 2