redhat man page for gllinewidth

GLLINEWIDTH(3G) 														   GLLINEWIDTH(3G)

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 |/x|>=|/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 rec-
       tangle 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 corre-
       sponding 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.	Likewise, there is a range for aliased line widths
       as well.  To query the range of supported widths and the size difference between supported widths within the range, call glGet  with  argu-
       ments GL_ALIASED_LINE_WIDTH_RANGE, GL_SMOOTH_LINE_WIDTH_RANGE, GL_SMOOTH_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.  Call glGet with GL_ALIASED_LINE_WIDTH_RANGE to  determine
       the maximum width.

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_ALIASED_LINE_WIDTH_RANGE
       glGet with argument GL_SMOOTH_LINE_WIDTH_RANGE
       glGet with argument GL_SMOOTH_LINE_WIDTH_GRANULARITY
       glIsEnabled with argument GL_LINE_SMOOTH

SEE ALSO
       glEnable(3G)

																   GLLINEWIDTH(3G)