Index for Section 3

Alphabetical listing for G

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gluNurbsProperty()
NAME
  gluNurbsProperty - set a NURBS property

SYNOPSIS
  void gluNurbsProperty(
	  GLUnurbs* nurb,
	  GLenum property,
	  GLfloat value );

PARAMETERS
  nurb
      Specifies the NURBS object (created with gluNewNurbsRenderer()).

  property
      Specifies the property to be set. Valid values are
      GLU_SAMPLING_TOLERANCE, GLU_DISPLAY_MODE, GLU_CULLING,
      GLU_AUTO_LOAD_MATRIX, GLU_PARAMETRIC_TOLERANCE, GLU_SAMPLING_METHOD,
      GLU_U_STEP, GLU_V_STEP, or GLU_NURBS_MODE_EXT.

  value
      Specifies the value of the indicated property. It may be a numeric
      value, or one of GLU_OUTLINE_POLYGON, GLU_FILL, GLU_OUTLINE_PATCH,
      GL_TRUE, GL_FALSE, GLU_PATH_LENGTH, GLU_PARAMETRIC_ERROR,
      GLU_DOMAIN_DISTANCE, GLU_NURBS_RENDERER_EXT, or
      GLU_NURBS_TESSELLATOR_EXT.

DESCRIPTION
  gluNurbsProperty() is used to control properties stored in a NURBS object.
  These properties affect the way that a NURBS curve is rendered. The
  accepted values for property are as follows:

  GLU_NURBS_MODE_EXT
      value should be set to be either GLU_NURBS_RENDERER_EXT or
      GLU_NURBS_TESSELLATOR_EXT. When set to GLU_NURBS_RENDERER_EXT, NURBS
      objects are tessellated into openGL primitives and sent to the pipeline
      for rendering. When set to GLU_NURBS_TESSELLATOR_EXT, NURBS objects are
      tessellated into openGL primitives but the vertices, normals, colors,
      and/or textures are retrieved back through a callback interface (see
      gluNurbsCallback()). This allows the user to cache the tessellated
      results for further processing.

  GLU_SAMPLING_METHOD
      Specifies how a NURBS surface should be tessellated.  value may be one
      of GLU_PATH_LENGTH, GLU_PARAMETRIC_ERROR, GLU_DOMAIN_DISTANCE,
      GLU_OBJECT_PATH_LENGTH_EXT, or GLU_OBJECT_PARAMETRIC_ERROR_EXT. When
      set to GLU_PATH_LENGTH, the surface is rendered so that the maximum
      length, in pixels, of the edges of the tessellation polygons is no
      greater than what is specified by GLU_SAMPLING_TOLERANCE.

      GLU_PARAMETRIC_ERROR specifies that the surface is rendered in such a
      way that the value specified by GLU_PARAMETRIC_TOLERANCE describes the
      maximum distance, in pixels, between the tessellation polygons and the
      surfaces they approximate.

      GLU_DOMAIN_DISTANCE allows users to specify, in parametric coordinates,
      how many sample points per unit length are taken in u, v direction.

      GLU_OBJECT_PATH_LENGTH_EXT is similar to GLU_PATH_LENGTH except that it
      is view independent, that is, the surface is rendered so that the
      maximum length, in object space, of edges of the tessellation polygons
      is no greater than what is specified by GLU_SAMPLING_TOLERANCE.

      GLU_OBJECT_PARAMETRIC_ERROR_EXT is similar to GLU_PARAMETRIC_ERROR
      except that it is view independent, that is, the surface is rendered in
      such a way that the value specified by GLU_PARAMETRIC_TOLERANCE
      describes the maximum distance, in object space, between the
      tessellation polygons and the surfaces they approximate.

      The initial value of GLU_SAMPLING_METHOD is GLU_PATH_LENGTH.

  GLU_SAMPLING_TOLERANCE
      Specifies the maximum length, in pixels or in object space length unit,
      to use when the sampling method is set to GLU_PATH_LENGTH or
      GLU_OBJECT_PATH_LENGTH_EXT. The NURBS code is conservative when
      rendering a curve or surface, so the actual length can be somewhat
      shorter.	The initial value is 50.0 pixels.

  GLU_PARAMETRIC_TOLERANCE
      Specifies the maximum distance, in pixels or in object space length
      unit, to use when the sampling method is GLU_PARAMETRIC_ERROR or
      GLU_OBJECT_PARAMETRIC_ERROR_EXT. The initial value is 0.5.

  GLU_U_STEP
      Specifies the number of sample points per unit length taken along the u
      axis in parametric coordinates. It is needed when GLU_SAMPLING_METHOD
      is set to GLU_DOMAIN_DISTANCE. The initial value is 100.

  GLU_V_STEP
      Specifies the number of sample points per unit length taken along the v
      axis in parametric coordinate. It is needed when GLU_SAMPLING_METHOD is
      set to GLU_DOMAIN_DISTANCE. The initial value is 100.

  GLU_DISPLAY_MODE
      value can be set to GLU_OUTLINE_POLYGON, GLU_FILL, or
      GLU_OUTLINE_PATCH. When GLU_NURBS_MODE_EXT is set to be
      GLU_NURBS_RENDERER_EXT, value defines how a NURBS surface should be
      rendered. When value is set to GLU_FILL, the surface is rendered as a
      set of polygons. When value is set to GLU_OUTLINE_POLYGON, the NURBS
      library draws only the outlines of the polygons created by
      tessellation.  When value is set to GLU_OUTLINE_PATCH just the outlines
      of patches and trim curves defined by the user are drawn.

      When GLU_NURBS_MODE_EXT is set to be GLU_NURBS_TESSELLATOR_EXT, value
      defines how a NURBS surface should be tessellated. When
      GLU_DISPLAY_MODE is set to GLU_FILL or GLU_OUTLINE_POLY, the NURBS
      surface is tessellated into openGL triangle primitives which can be
      retrieved back through callback functions. If GLU_DISPLAY_MODE is set
      to GLU_OUTLINE_PATCH, only the outlines of the patches and trim curves
      are generated as a sequence of line strips which can be retrieved back
      through callback functions.

      The initial value is GLU_FILL.

  GLU_CULLING
      value is a boolean value that, when set to GL_TRUE, indicates that a
      NURBS curve should be discarded prior to tessellation if its control
      points lie outside the current viewport. The initial value is GL_FALSE.

  GLU_AUTO_LOAD_MATRIX
      value is a boolean value. When set to GL_TRUE, the NURBS code downloads
      the projection matrix, the modelview matrix, and the viewport from the
      GL server to compute sampling and culling matrices for each NURBS curve
      that is rendered. Sampling and culling matrices are required to
      determine the tessellation of a NURBS surface into line segments or
      polygons and to cull a NURBS surface if it lies outside the viewport.

      If this mode is set to GL_FALSE, then the program needs to provide a
      projection matrix, a modelview matrix, and a viewport for the NURBS
      renderer to use to construct sampling and culling matrices. This can be
      done with the gluLoadSamplingMatrices() function.	 This mode is
      initially set to GL_TRUE. Changing it from GL_TRUE to GL_FALSE does not
      affect the sampling and culling matrices until
      gluLoadSamplingMatrices() is called.

NOTES
  If GLU_AUTO_LOAD_MATRIX is true, sampling and culling may be executed
  incorrectly if NURBS routines are compiled into a display list.

  A property of GLU_PARAMETRIC_TOLERANCE, GLU_SAMPLING_METHOD, GLU_U_STEP, or
  GLU_V_STEP, or a value of GLU_PATH_LENGTH, GLU_PARAMETRIC_ERROR,
  GLU_DOMAIN_DISTANCE are only available if the GLU version is 1.1 or
  greater. They are not valid parameters in GLU 1.0.

  gluGetString() can be used to determine the GLU version.

SEE ALSO
  gluGetNurbsProperty(3), gluLoadSamplingMatrices(3), gluNewNurbsRenderer(3),
  gluGetString(3), gluNurbsCallback(3)

Index for Section 3

Alphabetical listing for G

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