glGetMap.3gl

Name

  glGetMapdv, glGetMapfv, glGetMapiv - return evaluator	parameters

C Specification

  void glGetMapdv( GLenum target,
		   GLenum query,
		   GLdouble *v )
  void glGetMapfv( GLenum target,
		   GLenum query,
		   GLfloat *v )
  void glGetMapiv( GLenum target,
		   GLenum query,
		   GLint *v )

Parameters

  target  Specifies the	symbolic name of a map.	 Accepted values are
	  GL_MAP1_COLOR_4, GL_MAP1_INDEX, GL_MAP1_NORMAL,
	  GL_MAP1_TEXTURE_COORD_1, GL_MAP1_TEXTURE_COORD_2,
	  GL_MAP1_TEXTURE_COORD_3, GL_MAP1_TEXTURE_COORD_4, GL_MAP1_VERTEX_3,
	  GL_MAP1_VERTEX_4, GL_MAP2_COLOR_4 , GL_MAP2_INDEX, GL_MAP2_NORMAL,
	  GL_MAP2_TEXTURE_COORD_1, GL_MAP2_TEXTURE_COORD_2,
	  GL_MAP2_TEXTURE_COORD_3, GL_MAP2_TEXTURE_COORD_4, GL_MAP2_VERTEX_3,
	  and GL_MAP2_VERTEX_4.

  query	  Specifies which parameter to return.	Symbolic names GL_COEFF,
	  GL_ORDER, and	GL_DOMAIN are accepted.

  v	  Returns the requested	data.

Description

  glMap1 and glMap2 define evaluators.	glGetMap returns evaluator
  parameters.  target chooses a	map, query selects a specific parameter, and
  v points to storage where the	values will be returned.

  The acceptable values	for the	target parameter are described in the glMap1
  and  glMap2 reference	pages.

  query	can assume the following values:

  GL_COEFF	    v returns the control points for the evaluator function.
		    One-dimensional evaluators return order control points,
		    and	two-dimensional	evaluators return uorderxvorder
		    control points.  Each control point	consists of one, two,
		    three, or four integer, single-precision floating-point,
		    or double-precision	floating-point values, depending on
		    the	type of	the evaluator.	Two-dimensional	control
		    points are returned	in row-major order, incrementing the
		    uorder index quickly, and the vorder index after each
		    row.  Integer values, when requested, are computed by
		    rounding the internal floating-point values	to the
		    nearest integer values.

  GL_ORDER	    v returns the order	of the evaluator function.  One-
		    dimensional	evaluators return a single value, order.
		    Two-dimensional evaluators return two values, uorder and
		    vorder.

  GL_DOMAIN	    v returns the linear u and v mapping parameters.  One-
		    dimensional	evaluators return two values, u1 and u2, as
		    specified by glMap1.  Two-dimensional evaluators return
		    four values	(u1, u2, v1, and v2) as	specified by glMap2.
		    Integer values, when requested, are	computed by rounding
		    the	internal floating-point	values to the nearest integer
		    values.

Notes

  If an	error is generated, no change is made to the contents of v.

Errors

  GL_INVALID_ENUM is generated if either target	or query is not	an accepted
  value.

  GL_INVALID_OPERATION is generated if glGetMap	is called between a call to
  glBegin and the corresponding	call to	glEnd.

See Also

  glEvalCoord, glMap1, glMap2

Introduction | Alphabetic | Specification

Last Edited: Mon, May 22, 1995

AFV