glLineStipple
[New
- Windows 95, OEM Service Release 2]
The glLineStipple
function specifies the line stipple pattern.
void glLineStipple(
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GLint factor, |
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GLushort pattern |
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); |
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Parameters
factor
A multiplier
for each bit in the line stipple pattern. If factor is 3, for example,
each bit in the pattern will be used three times before the next bit in the
pattern is used. The factor parameter is clamped to the range [1, 256]
and defaults to one.
pattern
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, and the default pattern is
all ones.
Remarks
The glLineStipple
function specifies the line stipple pattern. 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 zero whenever glBegin is called, and before each line segment of a glBegin(GL_LINES)/glEnd
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 zero,
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. Rectangle s is rasterized or not based on the fragment rule
described for aliased lines; it counts rectangles rather than groups of
fragments.
Line
stippling is enabled or disabled using glEnable and glDisable 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 ones.
Initially, line stippling is disabled.
The following
functions retrieve information related to glLineStipple:
glGet
with argument GL_LINE_STIPPLE_PATTERN
glGet with
argument GL_LINE_STIPPLE_REPEAT
glIsEnabled with argument GL_LINE_STIPPLE
Error Codes
The following
are the error codes generated and their conditions.
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Error
Code |
Condition |
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GL_INVALID_OPERATION
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glLineStipple was called between a call to glBegin and the
corresponding call to glEnd. |
See Also