Index for Section 3G

Alphabetical listing for G

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glEvalCoord(3G)
NAME
  glEvalCoord, glEvalCoord1d, glEvalCoord1f, glEvalCoord2d, glEvalCoord2f,
  glEvalCoord1dv, glEvalCoord1fv, glEvalCoord2dv, glEvalCoord2fv - evaluate
  enabled one- and two-dimensional maps

SYNOPSIS
  void glEvalCoord1d(
	  GLdouble u );

  void glEvalCoord1f(
	  GLfloat u );

  void glEvalCoord2d(
	  GLdouble u,
	  GLdouble v );

  void glEvalCoord2f(
	  GLfloat u,
	  GLfloat v );

PARAMETERS
  u   Specifies a value that is the domain coordinate u to the basis function
      defined in a previous glMap1 or glMap2 command.

  v   Specifies a value that is the domain coordinate v to the basis function
      defined in a previous glMap2 command.  This argument is not present in
      a glEvalCoord1 command.

SYNOPSIS
  void glEvalCoord1dv(
	  const GLdouble *u );

  void glEvalCoord1fv(
	  const GLfloat *u );

  void glEvalCoord2dv(
	  const GLdouble *u );

  void glEvalCoord2fv(
	  const GLfloat *u );

PARAMETERS
  u   Specifies a pointer to an array containing either one or two domain
      coordinates. The first coordinate is u. The second coordinate is v,
      which is present only in glEvalCoord2() versions.

DESCRIPTION
  glEvalCoord1() evaluates enabled one-dimensional maps at argument u.
  glEvalCoord2() does the same for two-dimensional maps using two domain
  values, u and v. To define a map, call glMap1() and glMap2(); to enable and
  disable it, call glEnable() and glDisable().

  When one of the glEvalCoord() commands is issued, all currently enabled
  maps of the indicated dimension are evaluated. Then, for each enabled map,
  it is as if the corresponding GL command had been issued with the computed
  value. That is, if GL_MAP1_INDEX or GL_MAP2_INDEX is enabled, a glIndex()
  command is simulated. If GL_MAP1_COLOR_4 or GL_MAP2_COLOR_4 is enabled, a
  glColor() command is simulated.  If GL_MAP1_NORMAL or GL_MAP2_NORMAL is
  enabled, a normal vector is produced, and if any of
  GL_MAP1_TEXTURE_COORD_1, GL_MAP1_TEXTURE_COORD_2, GL_MAP1_TEXTURE_COORD_3,
  GL_MAP1_TEXTURE_COORD_4, GL_MAP2_TEXTURE_COORD_1, GL_MAP2_TEXTURE_COORD_2,
  GL_MAP2_TEXTURE_COORD_3, or GL_MAP2_TEXTURE_COORD_4 is enabled, then an
  appropriate glTexCoord() command is simulated.

  For color, color index, normal, and texture coordinates the GL uses
  evaluated values instead of current values for those evaluations that are
  enabled, and current values otherwise, However, the evaluated values do not
  update the current values. Thus, if glVertex() commands are interspersed
  with glEvalCoord() commands, the color, normal, and texture coordinates
  associated with the glVertex() commands are not affected by the values
  generated by the glEvalCoord() commands, but only by the most recent
  glColor(), glIndex(), glNormal(), and glTexCoord() commands.

  No commands are issued for maps that are not enabled. If more than one
  texture evaluation is enabled for a particular dimension (for example,
  GL_MAP2_TEXTURE_COORD_1 and GL_MAP2_TEXTURE_COORD_2), then only the
  evaluation of the map that produces the larger number of coordinates (in
  this case, GL_MAP2_TEXTURE_COORD_2) is carried out.  GL_MAP1_VERTEX_4
  overrides GL_MAP1_VERTEX_3, and GL_MAP2_VERTEX_4 overrides
  GL_MAP2_VERTEX_3, in the same manner. If neither a three- nor a four-
  component vertex map is enabled for the specified dimension, the
  glEvalCoord() command is ignored.

  If you have enabled automatic normal generation, by calling glEnable() with
  argument GL_AUTO_NORMAL, glEvalCoord2() generates surface normals
  analytically, regardless of the contents or enabling of the GL_MAP2_NORMAL
  map.	Let

	   dp	du
       m = -- x --
	   du	dv

  Then the generated normal n is

       n =  m
	  ||m||

  If automatic normal generation is disabled, the corresponding normal map
  GL_MAP2_NORMAL, if enabled, is used to produce a normal. If neither
  automatic normal generation nor a normal map is enabled, no normal is
  generated for glEvalCoord2() commands.

ASSOCIATED GETS
       glIsEnabled() with argument GL_MAP1_VERTEX_3
       glIsEnabled() with argument GL_MAP1_VERTEX_4
       glIsEnabled() with argument GL_MAP1_INDEX
       glIsEnabled() with argument GL_MAP1_COLOR_4
       glIsEnabled() with argument GL_MAP1_NORMAL
       glIsEnabled() with argument GL_MAP1_TEXTURE_COORD_1
       glIsEnabled() with argument GL_MAP1_TEXTURE_COORD_2
       glIsEnabled() with argument GL_MAP1_TEXTURE_COORD_3
       glIsEnabled() with argument GL_MAP1_TEXTURE_COORD_4
       glIsEnabled() with argument GL_MAP2_VERTEX_3
       glIsEnabled() with argument GL_MAP2_VERTEX_4
       glIsEnabled() with argument GL_MAP2_INDEX
       glIsEnabled() with argument GL_MAP2_COLOR_4
       glIsEnabled() with argument GL_MAP2_NORMAL
       glIsEnabled() with argument GL_MAP2_TEXTURE_COORD_1
       glIsEnabled() with argument GL_MAP2_TEXTURE_COORD_2
       glIsEnabled() with argument GL_MAP2_TEXTURE_COORD_3
       glIsEnabled() with argument GL_MAP2_TEXTURE_COORD_4
       glIsEnabled() with argument GL_AUTO_NORMAL
       glGetMap()

SEE ALSO
  glBegin(3), glColor(3), glEnable(3), glEvalMesh(3), glEvalPoint(3),
  glIndex(3), glMap1(3), glMap2(3), glMapGrid(3), glNormal(3), glTexCoord(3),
  glVertex(3)

Index for Section 3G

Alphabetical listing for G

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