DragonFly On-Line Manual Pages

GLLINEWIDTH()                                                    GLLINEWIDTH()

NAME
       glLineWidth - specify the width of rasterized lines

C SPECIFICATION
       void glLineWidth( GLfloat width )

PARAMETERS
       width  Specifies the width of rasterized lines.  The initial value is
              1.

DESCRIPTION
       glLineWidth specifies the rasterized width of both aliased and
       antialiased lines.  Using a line width other than 1 has different
       effects, depending on whether line antialiasing is enabled.  To enable
       and disable line antialiasing, call glEnable and glDisable with
       argument GL_LINE_SMOOTH. Line antialiasing is initially disabled.

       If line antialiasing is disabled, the actual width is determined by
       rounding the supplied width to the nearest integer.  (If the rounding
       results in the value 0, it is as if the line width were 1.)  If
       | DELTA x | >= | DELTA y |,
       i pixels are filled in each column that is rasterized, where i is the
       rounded value of width.  Otherwise, i pixels are filled in each row
       that is rasterized.

       If antialiasing is enabled, line rasterization produces a fragment for
       each pixel square that intersects the region lying within the rectangle
       having width equal to the current line width, length equal to the
       actual length of the line, and centered on the mathematical line
       segment.  The coverage value for each fragment is the window coordinate
       area of the intersection of the rectangular region with the
       corresponding pixel square.  This value is saved and used in the final
       rasterization step.

       Not all widths can be supported when line antialiasing is enabled.  If
       an unsupported width is requested, the nearest supported width is used.
       Only width 1 is guaranteed to be supported; others depend on the
       implementation.  To query the range of supported widths and the size
       difference between supported widths within the range, call glGet with
       arguments GL_LINE_WIDTH_RANGE and GL_LINE_WIDTH_GRANULARITY.

NOTES
       The line width specified by glLineWidth is always returned when
       GL_LINE_WIDTH is queried.  Clamping and rounding for aliased and
       antialiased lines have no effect on the specified value.

       Nonantialiased line width may be clamped to an implementation-dependent
       maximum.  Although this maximum cannot be queried, it must be no less
       than the maximum value for antialiased lines, rounded to the nearest
       integer value.

ERRORS
       GL_INVALID_VALUE is generated if width is less than or equal to 0.

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

ASSOCIATED GETS
       glGet with argument GL_LINE_WIDTH
       glGet with argument GL_LINE_WIDTH_RANGE
       glGet with argument GL_LINE_WIDTH_GRANULARITY
       glIsEnabled with argument GL_LINE_SMOOTH

SEE ALSO
       glEnable

                                                                 GLLINEWIDTH()