glLineWidth(3gl)

1GLLINEWIDTH(3G)                                                GLLINEWIDTH(3G)
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NAME

6       glLineWidth - specify the width of rasterized lines
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C SPECIFICATION

10       void glLineWidth( GLfloat width )
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PARAMETERS

14       width  Specifies  the  width of rasterized lines.  The initial value is
15              1.
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DESCRIPTION

18       glLineWidth  specifies  the  rasterized  width  of  both  aliased   and
19       antialiased  lines.   Using  a  line  width  other than 1 has different
20       effects, depending on whether line antialiasing is enabled.  To  enable
21       and  disable  line antialiasing, call glEnable and glDisable with argu‐
22       ment GL_LINE_SMOOTH. Line antialiasing is initially disabled.
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24       If line antialiasing is disabled, the actual  width  is  determined  by
25       rounding  the  supplied width to the nearest integer.  (If the rounding
26       results in the value 0, it is  as  if  the  line  width  were  1.)   If
27       |Δx|≥|Δy|, i pixels are filled in each column that is rasterized, where
28       i is the rounded value of width.  Otherwise, i  pixels  are  filled  in
29       each row that is rasterized.
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31       If  antialiasing is enabled, line rasterization produces a fragment for
32       each pixel square that intersects the region lying within the rectangle
33       having  width  equal  to  the  current  line width, length equal to the
34       actual length of the line, and centered on the mathematical  line  seg‐
35       ment.   The  coverage  value for each fragment is the window coordinate
36       area of the intersection of the rectangular region with the correspond‐
37       ing pixel square.  This value is saved and used in the final rasteriza‐
38       tion step.
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40       Not all widths can be supported when line antialiasing is  enabled.  If
41       an unsupported width is requested, the nearest supported width is used.
42       Only width 1 is guaranteed to be supported; others depend on the imple‐
43       mentation.  Likewise, there is a range for aliased line widths as well.
44       To query the range of supported widths and the size difference  between
45       supported   widths   within   the  range,  call  glGet  with  arguments
46       GL_ALIASED_LINE_WIDTH_RANGE,                GL_SMOOTH_LINE_WIDTH_RANGE,
47       GL_SMOOTH_LINE_WIDTH_GRANULARITY.
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NOTES

50       The  line  width  specified  by  glLineWidth  is  always  returned when
51       GL_LINE_WIDTH is  queried.   Clamping  and  rounding  for  aliased  and
52       antialiased lines have no effect on the specified value.
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54       Nonantialiased line width may be clamped to an implementation-dependent
55       maximum.  Call glGet with GL_ALIASED_LINE_WIDTH_RANGE to determine  the
56       maximum width.
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ERRORS

59       GL_INVALID_VALUE is generated if width is less than or equal to 0.
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61       GL_INVALID_OPERATION  is  generated  if glLineWidth is executed between
62       the execution of glBegin and the corresponding execution of glEnd.
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ASSOCIATED GETS

65       glGet with argument GL_LINE_WIDTH
66       glGet with argument GL_ALIASED_LINE_WIDTH_RANGE
67       glGet with argument GL_SMOOTH_LINE_WIDTH_RANGE
68       glGet with argument GL_SMOOTH_LINE_WIDTH_GRANULARITY
69       glIsEnabled with argument GL_LINE_SMOOTH
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