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 argu-
       ment 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
       |Δx|≥|Δy|,  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  rectan-
       gle  having width equal to the current line width, length equal to the
       actual length of the line, and centered on the mathematical line	 seg-
       ment.   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 ras-
       terization 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
       arguments   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-depen-
       dent maximum.  Call glGet with GL_ALIASED_LINE_WIDTH_RANGE  to  deter-
       mine 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)