glLineStipple.3gl

Name

  glLineStipple	- specify the line stipple pattern

C Specification

  void glLineStipple( GLint factor,
		      GLushort 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	will be	used
	   three times before the next bit in the pattern is used.  factor is
	   clamped to the range	[1, 256] and defaults to one.

  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, and the default pattern is all ones.

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	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, counting 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.

Errors

  GL_INVALID_OPERATION is generated if glLineStipple is	executed between the
  execution of glBegin and the corresponding execution of glEnd.

Associated Gets

  glGet	with argument GL_LINE_STIPPLE_PATTERN
  glGet	with argument GL_LINE_STIPPLE_REPEAT
  glIsEnabled with argument GL_LINE_STIPPLE

See Also

  glLineWidth, glPolygonStipple

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Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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