fglLineWidth(3G)

NAME
     fglLineWidth - specify the width of rasterized lines


FORTRAN SPECIFICATION
     SUBROUTINE fglLineWidth( REAL*4 width )


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

DESCRIPTION
     fglLineWidth 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 fglEnable and fglDisable 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 fglGet with
     arguments GL_LINE_WIDTH_RANGE and GL_LINE_WIDTH_GRANULARITY.

NOTES
     The line width specified by fglLineWidth 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 fglLineWidth is executed between the
     execution of fglBegin and the corresponding execution of fglEnd.

ASSOCIATED GETS
     fglGet with argument GL_LINE_WIDTH
     fglGet with argument GL_LINE_WIDTH_RANGE
     fglGet with argument GL_LINE_WIDTH_GRANULARITY
     fglIsEnabled with argument GL_LINE_SMOOTH


MACHINE DEPENDENCIES
     InfiniteReality systems do not support antialiased lines in color-index
     rendering contexts.  (They are rendered as ordinary lines instead.)


SEE ALSO
     fglBlendFunc, fglEnable, fglHint