Digital Equipment Corporation OpenGL man pages



  glPolygonStipple - set the polygon stippling pattern

C Specification

  void glPolygonStipple( const GLubyte *mask )


  mask	Specifies a pointer to a 32x32 stipple pattern that will be unpacked
	from memory in the same	way that glDrawPixels unpacks pixels.


  Polygon stippling, like line stippling (see glLineStipple), masks out
  certain fragments produced by	rasterization, creating	a pattern.  Stippling
  is independent of polygon antialiasing.

  mask is a pointer to a 32x32 stipple pattern that is stored in memory	just
  like the pixel data supplied to a glDrawPixels with height and width both
  equal	to 32, a pixel format of GL_COLOR_INDEX, and data type of GL_BITMAP.
  That is, the stipple pattern is represented as a 32x32 array of 1-bit	color
  indices packed in unsigned bytes.  glPixelStore parameters like
  GL_UNPACK_SWAP_BYTES and GL_UNPACK_LSB_FIRST affect the assembling of	the
  bits into a stipple pattern.	Pixel transfer operations (shift, offset,
  pixel	map) are not applied to	the stipple image, however.

  Polygon stippling is enabled and disabled with glEnable and glDisable,
  using	argument GL_POLYGON_STIPPLE.  If enabled, a rasterized polygon
  fragment with	window coordinates x  and y  is	sent to	the next stage of the
                                    w      w
  GL if	and only if the	(x  mod 32)th bit is the (y  mod 32)th row of the
                          w                        w
  stipple pattern is one.  When	polygon	stippling is disabled, it is as	if
  the stipple pattern were all ones.


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

Associated Gets

  glIsEnabled with argument GL_POLYGON_STIPPLE

See Also

  glDrawPixels,	glLineStipple, glPixelStore, glPixelTransfer

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