2003-2004
Silicon Graphics, Inc.
glLineWidth
3G
glLineWidth
glLineWidth
glLineWidthx
specify the width of rasterized lines
C Specification
void glLineWidth
GLfloat width
void glLineWidthx
GLfixed 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
|
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 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. Likewise, there
is a range for aliased line widths as well. To query the range
of supported widths, call
glGet
with arguments
GL_ALIASED_LINE_WIDTH_RANGE or
GL_SMOOTH_LINE_WIDTH_RANGE.
Notes
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.
Associated Gets
glGet
with argument GL_ALIASED_LINE_WIDTH_RANGE
glGet
with argument GL_SMOOTH_LINE_WIDTH_RANGE
See Also
glEnable,
glGet
Copyright
Copyright 2003-2004
Silicon Graphics, Inc. This document is licensed under the SGI
Free Software B License. For details, see
https://khronos.org/registry/OpenGL-Refpages/LICENSES/LicenseRef-FreeB.txt.