Digital Equipment Corporation OpenGL man pages



  gluLoadSamplingMatrices - load NURBS sampling	and culling matrices

C Specification

  void gluLoadSamplingMatrices(	GLUnurbsObj *nobj,
				const GLfloat modelMatrix[16],
				const GLfloat projMatrix[16],
				const GLint viewport[4]); )


  nobj	       Specifies the NURBS object (created with	gluNewNurbsRenderer).

  modelMatrix  Specifies a modelview matrix (as	from a glGetFloatv call).

  projMatrix   Specifies a projection matrix (as from a	glGetFloatv call).

  viewport;    Specifies a viewport (as	from a glGetIntegerv call).


  gluLoadSamplingMatrices uses modelMatrix, projMatrix,	and viewport; to
  recompute the	sampling and culling matrices stored in	nobj.  The sampling
  matrix determines how	finely a NURBS curve or	surface	must be	tessellated
  to satisfy the sampling tolerance (as	determined by the
  GLU_SAMPLING_TOLERANCE property).  The  culling matrix is used in deciding
  if a NURBS curve or surface should be	culled before rendering	(when the
  GLU_CULLING property is turned on).

  gluLoadSamplingMatrices is necessary only if the GLU_AUTO_LOAD_MATRIX
  property is turned off (see gluNurbsProperty).  Although it can be
  convenient to	leave the GLU_AUTO_LOAD_MATRIX property	turned on, there can
  be a performance penalty for doing so.  (A round trip	to the OpenGL server
  is needed to fetch the current values	of the modelview matrix, projection
  matrix, and viewport.)

See Also

  gluGetNurbsProperty, gluNewNurbsRenderer, gluNurbsProperty

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