fglLineStipple(3G) OpenGL Reference fglLineStipple(3G)NAME
fglLineStipple - specify the line stipple pattern
FORTRAN SPECIFICATION
SUBROUTINE fglLineStipple( INTEGER*4 factor,
INTEGER*2 pattern )
PARAMETERS
factor Specifies a multiplier for each bit in the line stipple pattern.
If factor is 3, for example, each bit in the pattern is used
three times before the next bit in the pattern is used. factor
is clamped to the range [1, 256] and defaults to 1.
pattern Specifies a 16-bit integer whose bit pattern determines which
fragments of a line will be drawn when the line is rasterized.
Bit zero is used first; the default pattern is all 1's.
DESCRIPTION
Line stippling masks out certain fragments produced by rasterization;
those fragments will not be drawn. The masking is achieved by using
three parameters: the 16-bit line stipple pattern pattern, the repeat
count factor, and an integer stipple counter s.
Counter s is reset to 0 whenever fglBegin is called, and before each line
segment of a fglBegin(GL_LINES)/fglEnd sequence is generated. It is
incremented after each fragment of a unit width aliased line segment is
generated, or after each i fragments of an i width line segment are
generated. The i fragments associated with count s are masked out if
pattern bit (s / factor) mod 16
is 0, otherwise these fragments are sent to the frame buffer. Bit zero
of pattern is the least significant bit.
Antialiased lines are treated as a sequence of 1xwidth rectangles for
purposes of stippling. Whether rectagle s is rasterized or not depends
on the fragment rule described for aliased lines, counting rectangles
rather than groups of fragments.
To enable and disable line stippling, call fglEnable and fglDisable with
argument GL_LINE_STIPPLE. When enabled, the line stipple pattern is
applied as described above. When disabled, it is as if the pattern were
all 1's. Initially, line stippling is disabled.
ERRORS
GL_INVALID_OPERATION is generated if fglLineStipple is executed between
the execution of fglBegin and the corresponding execution of fglEnd.
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fglLineStipple(3G) OpenGL Reference fglLineStipple(3G)ASSOCIATED GETS
fglGet with argument GL_LINE_STIPPLE_PATTERN
fglGet with argument GL_LINE_STIPPLE_REPEAT
fglIsEnabled with argument GL_LINE_STIPPLE
SEE ALSO
fglLineWidth, fglPolygonStipple
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